>
> If I paid that much for an = automobile I'd=20 have to drive it 15 years too.
>
> Instead, I pay 1/3 that = much and=20 drive it 5 years. So, as I see it, I
> end up with a new = car, with=20 all the newest style and latest toys, every
> 5 years and spend = the same=20 amount of money for the period.
>
>=20 Economics......ugh!
>
> 73
> Bob K4TAX
And have all = the=20 problems associated with that = decision.....

>Peter,
>
>US=20 engineers aren't paid enough to be able to drive Mercedes like=20 their
>bosses do. Hi!!
>
>73 de
>
>Dave,=20 WT8R
>
Neither are European engineers, I bought it second hand = two=20 years ago for
less than a new Skoda Felicia (VW Polo clone made in = the Czech=20 republic),
with 80K miles on it and looking as good as new. So far = I've had=20 the
privilege to drive one of the best engineered cars in the world,=20 had
absolutely no problems, and great gas (diesel) mileage, all at = much=20 lower
cost per mile than your average dinky Japanese or US "economy"=20 cars.
In my book that is a very sound engineering = decision!

Vy 73=20 de OZ1PIF, Peter

Sound clips from OX2K operation "off the = air":
http://hjem.get2net= .dk/oz1pif/OX2K-sound.htm

********** =20 OZ1PIF **************
email: oz1pif(no-spam-filler)@get2net.dk
http://hjem.get2net.dk/oz1pif<= BR>Shack=20 Ph. +45 4619 3208
Snailmail:
Peter Frenning
Ternevej = 23
DK-4130 Viby=20 Sj.
Denmark
***********************************

------=_NextPart_000_0055_01C08FC7.52238FA0-- -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From w2cqm@juno.com Mon Feb 5 23:03:37 2001 From: w2cqm@juno.com (w2cqm@juno.com) Date: Mon, 5 Feb 2001 18:03:37 -0500 Subject: [AMPS] SELL: Drake L4B Dedicated for 6m Message-ID: <20010205.180934.-186521.0.w2cqm@juno.com> SELL: Absolutely mint Drake L4B linear amplifier (serial # 2631) dedicated to 6 meters running a pair of Eimac 3-500's. Easily develops 1000 watts OUTPUT with 80W of drive (200ma of grid current) in the SSB condition. Obviously, can be pushed a bit more but not recommended. All power supply and control circuitry is stock Drake except for the RF deck changes noted below: a. parasitic chokes rewound b. HV plate choke rewound c. Dedicated 6 meter silvered, broad banded coil allows for 1 mHz DX chasing excursions without retuning. d. wide spaced, low capacitance antenna tune air variable allows for smooth plate resonance tuning. e. moderate capacitance antenna tune air variable provides for smooth antenna matching f. "T" match exciter input control provides for achieving an extremely smooth "zero" SWR and maximum exciter drive. This is especially important today because of the often temperamental nature of the solid state rigs that shut themselves down. This control replaces the OEM bandswitch/coil assembly on the deck; however, careful attention was paid to the retrofit so that the amplifier does not appear to be modified in any way. The front panel is absolutely stock Drake (in appearance). The only changes are: a. Standby/operate switch functions normally but AGC removed. Rotates rather than push/pull. b. "T" match tuned exciter input control replaces the Drake bandswitch/coil assembly. c. Meter selection switch continues to monitor all functions. No circuit changes. The Drake RF deck chassis is absolutely perfect in all aspects. There are no scratches, dings, or abrasions. The chassis interior is clean and bright with no smoke residue. There has been no "butchering" of the wiring. The L4PS matching power supply remains OEM Drake with no circuit changes. The PS cabinet has some barely visible blemishes on the top but there are no bangs or dents. The original Drake quality control tag is still attached to the power cord. The package includes the original Drake manual. A schematic is provided outlining the basic changes. Troubleshooting is easy to follow with the Drake schematic because of the minimal circuit alterations. $1050. Prefer pickup in the New York City or Scranton Pennsylvania area or will be in Dayton. Ron W2CQM New York City http://homestead.juno.com/W2CQM/files/DRake6mpanel.JPG http://homestead.juno.com/W2CQM/files/Drake6mdeck.JPG Epilogue: See QRZ.COM for the listing of the most recent articles written for QST and 73 Magazine authored by W2CQM. http://www.qrz.com/callsign.html?callsign=w2cqm -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Tue Feb 6 08:50:29 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Tue, 6 Feb 2001 08:50:29 -0000 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D7F9@excalibur.swindon.msl.mitel.com> Rich says: >Consider that the price of a 25w rheostat is under $6. Yes. Which is why in a home brew amp, you'd fit one, without argument. In the commercial world, $6 on a component is at least $12 on the ex-works price. In the case of a variable or preset control, where testing and adjustment is required, add another $5. These are the real costs you find in a production environment. So all of a sudden, our filament rheostat is costing $20 plus sales tax to the end user. Similar sort of add ons happen for step start, increased cooling for the tank circuit and so on. Very soon, you're talking of the $5k plus amplifier. Which is part of the explanation of why Uncle Sam pays so much for equipment. Other parts of that are procurement practices, but that's another story. Nobody goes bankrupt in the long term; but there's a limited market for Rolls-Royces, as Colin's friend found. Ham amps are meant for the average ham, and of necessity, they get cut down to what the ham will pay. Which is why I'm so keen on home brew..... 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 11:44:53 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 03:44:53 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102061145.f16Bj5914186@contesting.com> >Rich says: > >>Consider that the price of a 25w rheostat is under $6. > >Yes. Which is why in a home brew amp, you'd fit one, >without argument. > >In the commercial world, $6 on a component is at least >$12 on the ex-works price. In the case of a variable or > preset control, where testing and adjustment is >required, add another $5. These are the real costs you >find in a production environment. Collins Radio managed to use one in the KWS-1. > >So all of a sudden, our filament rheostat is costing $20 >plus sales tax to the end user. wasting a $650 8877 for lack of spending $6 is bananas. >Similar sort of add ons >happen for step start, increased cooling for the tank >circuit and so on. Very soon, you're talking of the $5k >plus amplifier. Which is part of the explanation of why >Uncle Sam pays so much for equipment. Other parts >of that are procurement practices, but that's another >story. > $700 crapper seats, et cetera is how the military-industrial complex conceals "black project" funds. ' cheers, Peter > > > > - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Tue Feb 6 12:07:56 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Tue, 6 Feb 2001 12:07:56 -0000 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D7FD@excalibur.swindon.msl.mitel.com> Rich says: >wasting a $650 8877 for lack of spending $6 is bananas. Depends on whose bottom line you're thinking of. Unless it can be shown that the tube consistently failed within its guarantee period because of the lack of a rheostat, bottom line says 'don't fit it'. Somebody else picks up the bill. Would I fit it on a homebrew rig? Sure - unless I was having a stabilised power supply instead. But if I'm making amps for a living, unless it's going to be a frequent failure that can be proved to be a lacking rheostat, it don't go in. Poor engineering? Maybe. Keeping in profit..YES! >$700 crapper seats, et cetera is how the military-industrial > complex conceals "black project" funds. Not entirely. It works like this: The Army needs hammers, engineering, 1 pound. If you got to a recognised supplier and order hammers out of the catalogue, Senator Gridleak starts bitching that a hammer manufacturer in Crapville ND or whatever (which is his state) didn't get a chance. So the military has to come out with an 'RFP' (Request for Proposal) and everybody produces a mound of paper, and there's a load of travel to meetings. Then they come out with an RFQ (Request for Quotation), and there's more paper as everyone tries to get the lowest bid/ fastest delivery etc. Then there's the 'BFO' (Best and Final Offer) where they play the bidders off against each other. When the order finally gets placed, the inspection starts of the hickory for the handles (did it come from renewable forests properly managed?) and the casting quality (does the foundry meet EPA requirements?), and the inspectors have to be housed in your factory etc. Then it has to be packaged, and then you wait to be paid. The other side of the coin is that GI Joe in a fox hole somewhere in the back of beyond overseas, with shells arriving all around him can't go to Walmart if he's stuck for a hammer.... That's how the costs build up for mil stuff, and that's why COTS (Commercial Off The Shelf) is popular in some quarters. Sorry to go on - I've had enough of dealing with mil procurement to last the rest of my life.........when you're the sole source, it's a lot of grief you don't need! 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W8JI@contesting.com Tue Feb 6 13:58:02 2001 From: W8JI@contesting.com (Tom Rauch) Date: Tue, 6 Feb 2001 08:58:02 -0500 Subject: [AMPS] SB-220: Operate/Standby Switch In-Reply-To: <6CEB3A36096CD2119FEE00A0C9410EC201D7D7F9@excalibur.swindon.msl.mitel.com> Message-ID: <3A7FBC9A.23462.2E94744@localhost> Hi Peter, My "spam" filter made me miss most of this, but I should add a few comments. > Rich says: > > >Consider that the price of a 25w rheostat is under $6. Of course Rich always leaves a few things out. 1.) There would have to be some reasonable assurance lack of a rheostat actually is causing a problem with tube life. That doesn't seem to be the case since almost 80% of tube failures are G/K shorts and the remaining percentage mostly due to loss of vacuum or voltage breakdown failures. 2.) If the rheostat was added, provisions would have to be made for monitoring voltage accurately. Most expensive panel meters are only 2% of FS anywhere on the scale, and to make that worse it would be driven by a rectifier and true-RMS filtering system that would be full of components with tolerances. By the time all is said and done, the $6 rheostat would add $100 of cost to the PA if you bought new parts (which commercially you have to do, unless you are someone who foolishly mixes in surplus parts) and would have to be hand calibrated. 3.) If you get past the above you have given someone, who's skill at reading meters, eyesight, and common sense are unknown, ability at the mere tweek of a knob to RUIN a tube quickly. You can bet that person, even if he did something wrong, would demand a free tube...or it could be a V31BB who actually rewired his transformers for 200 volts (on a 240 volt main ) so he could run more power! 4.) Even if you stopped some life reduction by allowing filament adjustment, the end result would be to add a certain number of hours to the tube life. It would not make the tube live forever, and very likely would not improve it a measurable amount in Amateur service. 5.) Factually the easier you make it for someone to screw up or abuse the equipment, the more likely it will happen. There would be a reasonably large percentage of additional failure from component failures and customer abuse or errors. > Yes. Which is why in a home brew amp, you'd fit one, > without argument. Not me. None of my amps have rheostats for filaments. The reason is simple. My line voltage varies from 241 volts to 252 volts from the highest demand periods of summer to the lowest demand times in winter, and I am in a rural area many miles from generating plants and even HV transmission lines. That's well within the acceptable range of tube filaments. I simply set the transformer taps at the correct mean voltage, and let it go at that. Even if voltage stability of my mains was + - 5% or more, I'm sure I'd never see the difference in failures because I've never had a stripped cathode or open filament. By far the biggest stress in amateur service is the constant thermal cycling of the filament, and not the running time deterioration. If I wanted to make tubes last longer, I'd quit turning the filaments off and on a few times every day. I don't do that because it cost me more in energy to run the blowers and filaments than it costs in tube life reduction. Most tube failures are due to manufacturing defects in the tubes, or abuse. Virtually none are controllable and correctable failures. It's easy to sit in a room parked in from of a computer, never build a commercial product, and take unfounded pot-shots at the world. It's quite another view when you spend time analyzing returns and looking at the cost to reduce the few things that are controllable. Factually, whether people like it or not, every single prevention system ADDS failures in other areas while reducing failures in the target area. It is easy for additional problems to offset the benefits, and wind up costing more that leaving things alone. That's why you NEVER, from an engineering standpoint, add components that have negative impacts on other areas of the system. The rheostat Rich "harps" about is a prime example of something that can cause more problems than it cures, because it "corrects" what is almost always a non-problem while adding unreliablity and the potential for damaging human error. The trend of amplifier design, in the low-tech world we are in, will be to REMOVE customer controls...not add them. Especially when they have the potential to do harm and are unlikely to do any good. > In the commercial world, $6 on a component is at least > $12 on the ex-works price. In the case of a variable or > preset control, where testing and adjustment is > required, add another $5. These are the real costs you > find in a production environment. You forgot the meter and circuits needed, and underestimate the time required to make sure the system is calibrated, as well as the cost of failures in the additional parts (any one of which could actually cause a tube failure). > So all of a sudden, our filament rheostat is costing $20 > plus sales tax to the end user. Similar sort of add ons > happen for step start, increased cooling for the tank > circuit and so on. Very soon, you're talking of the $5k > plus amplifier. Which is part of the explanation of why I did a cost estimate on adjustable filament voltage at one time, and asked for statistical data from Eimac on their tube returns. They said other than amps that run the filaments at 10-20% extra voltage (Dentron and two other manufacturers) they saw virtually no preventable filament failures. Such failures were "in the noise floor" of the statistics. Unlike Rich, I trust what Eimac tells me. The out-the-door cost to correct that non-problem was about $100 back in 1988. 73, Tom W8JI w8ji@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From wb4mnf@atl.org Tue Feb 6 14:08:05 2001 From: wb4mnf@atl.org (Bob Duckworth) Date: Tue, 6 Feb 2001 09:08:05 -0500 Subject: [AMPS] Grid block keying of SB200 for QSK??? Message-ID: <200102061407.JAA15878@hat-trick.atl.org> Thanks for suggesitons. and Thanks BAMA! It sure helps to have a schematic. SB200 has grids at RF ground and cuts tubes off with a neg bias to grids. I'm going to nip the wire, lock the relays down and try keying via the neg 90V keyed line from the HW-16. If this doesn't work, will look at either MOSFET or using the neg bias from the amp for keying the HW-16 rather than the other way around. Will post pix and results to www early next week. -bob -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Tue Feb 6 14:18:42 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Tue, 6 Feb 2001 14:18:42 -0000 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D805@excalibur.swindon.msl.mitel.com> Tom says; >By far the biggest stress in amateur service is the > constant thermal cycling of the filament That's where the rheostat comes in handy - assuming proper proportions, it limits surge current. Of course, so does a suitably designed surge limiting filament transformer, but that can be a bit more expensive. >provisions would have to be made for monitoring voltage >accurately I assumed external metering, but point taken, especially on cost. Of course, there's the BBC(?) experience with the 4CX250B, showing that some filament voltage reduction can help life. GW4FRX has chapter and verse on that, and, I seem to remember, has published the info here on occasion. Whether, in amateur service, you'd notice the difference is another matter...... The real cost of a component in a piece of gear can be quite high. I even convinced purchasing on one occasion that a 22p cermet trim pot was cheaper than a 3p carbon one, because 15% of the carbon ones broke or otherwise failed in the test department - and it cost just 8 times as much as the component cost of the cermet to replace the failed part. Even adjusting a preset in the factory costs a lot of money. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W8JI@contesting.com Tue Feb 6 14:39:46 2001 From: W8JI@contesting.com (Tom Rauch) Date: Tue, 6 Feb 2001 09:39:46 -0500 Subject: [AMPS] SB-220: Operate/Standby Switch In-Reply-To: <6CEB3A36096CD2119FEE00A0C9410EC201D7D805@excalibur.swindon.msl.mitel.com> Message-ID: <3A7FC662.3523.30F7DD6@localhost> > >By far the biggest stress in amateur service is the > > constant thermal cycling of the filament > > That's where the rheostat comes in handy - assuming proper > proportions, it limits surge current. > Of course, so does a suitably designed surge limiting filament > transformer, but that can be a bit more expensive. Not really, a suitable current limiting transformer costs LESS than a transformer that allows excessive starting current. You do have to allow for temperature rise, however, and not box it in. > >provisions would have to be made for monitoring voltage > >accurately > > I assumed external metering, but point taken, especially on cost. Oh sure! Let the guy use his handy $25 dollar VOM to set voltage! I've seen six cases of low cathode emission in the past 18 years in 8877's. In five of those cases, the filament systems were modified to reduce voltage and they missed by a few percent. 73, Tom W8JI w8ji@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From plantin@tcomlp.com Tue Feb 6 14:43:31 2001 From: plantin@tcomlp.com (Bruce Plantin) Date: Tue, 06 Feb 2001 09:43:31 -0500 Subject: [AMPS] QSK-5 Message-ID: Hi all, I have a diagram of a Heathkit SB2001-1 QSK board. I believe this board is identcal or also identical to the Ameritron board but have no Ameritron schematic. My confusion is: When in the RX mode, I can't see the RF path from the antenna connection to the xcvr connection. Is my Heathkit schematic missing something or am I missing something? At this time I don't have the actual Heathkit board in hand to verify the schematic against the board for the answer. I bet W8JI might know the history of these boards and the answer.. Regards, Bruce W3BP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Tue Feb 6 14:48:21 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Tue, 6 Feb 2001 14:48:21 -0000 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D807@excalibur.swindon.msl.mitel.com> Tom said: >Oh sure! Let the guy use his handy $25 dollar VOM to set voltage! have you looked at the accuracy of these cheap digital voltmeters? The ones I've seen were remarkably good...with no RF around. >I've seen six cases of low cathode emission in the >past 18 years in 8877's. In five of those cases, >the filament systems were modified to reduce voltage > and they missed by a few percent. can you prove it was that? Did it repeat on the replacements? As a percentage of the number of 8877s made, that must be miniscule. Just to stir things up, what percentage of 8877s made (not just in ham gear) have failed because of parasitics? 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From paulc@mediaone.net Tue Feb 6 14:50:14 2001 From: paulc@mediaone.net (Paul Christensen) Date: Tue, 6 Feb 2001 09:50:14 -0500 Subject: [AMPS] SB-220: Operate/Standby Switch References: <3A7FBC9A.23462.2E94744@localhost> Message-ID: <00b501c0904c$2b661b00$6501a8c0@paulch> > 1.) There would have to be some reasonable assurance lack of a > rheostat actually is causing a problem with tube life. That doesn't > seem to be the case since almost 80% of tube failures are G/K > shorts and the remaining percentage mostly due to loss of vacuum > or voltage breakdown failures. However, most commercial amps, including every commercial transmitter in the AM/FM broadcast industry use a rheostat to control filament voltage. In commercial applications, it's common practice to run a new tube, (particularly metal/ceramic power tubes) at the manufacturer's specified filament voltage for 500 hours of operation, then reduce the filament voltage at or slightly above the point where the emission begins to drop off. Is this directly related to tube failure? Maybe. Maybe not. But, tube life can be greatly extended when using this method. It's a well-settled fact that power tube life is substantially shortened when operating a power tube above the manufacturer's recommended filament voltage. In 20 years of commercial broadcasting as a V.P. of Engineering, I can honestly say that I had never experienced an open filament due to filamant over-voltage, but premature emission reduction can be always be expected. Going to the station's G.M. with the news that a 4CX20,000D has to be replaced or rebuilt is never a pleasant experience. > 2.) If the rheostat was added, provisions would have to be made for > monitoring voltage accurately. Most expensive panel meters are > only 2% of FS anywhere on the scale, and to make that worse it > would be driven by a rectifier and true-RMS filtering system that > would be full of components with tolerances. By the time all is said > and done, the $6 rheostat would add $100 of cost to the PA if you > bought new parts (which commercially you have to do, unless you > are someone who foolishly mixes in surplus parts) and would have > to be hand calibrated. Forget the meter. Simply add two insulated/isolated test jacks to monitor filamant voltage with a hand-held true R.M.S. DVM, or iron vane voltmeter. Those of us that feel filamant voltage sampling is important will use it. Those who don't aren't stuck with a precision $100 movement. > 4.) Even if you stopped some life reduction by allowing filament > adjustment, the end result would be to add a certain number of > hours to the tube life. It would not make the tube live forever, and > very likely would not improve it a measurable amount in Amateur > service. Perhaps, but nobody is asking the tube to live forever. I simply want to be able to control the voltage to the tube if I desire so that my elevated 255 VDC AC mains doesn't translate to 6.5V on a tube rated for 6.0 V. Let me make the choice. A rheostat and front panel test points is all I need. I realize that amateur service is not a 24/7 operation like that of broadcasting, but the benefit can still be realized just like adding step-start inrush protection. > 5.) Factually the easier you make it for someone to screw up or > abuse the equipment, the more likely it will happen. There would be > a reasonably large percentage of additional failure from component > failures and customer abuse or errors. Any more factual than the presence of the load and plate tune controls on the amp? I can find plently of positions to kill my amp with improper tuning technique and excessive overdrive. To protect against these conditions from the operater costs no less than a rheostat. Keeping the adjutsable limits reasonable on a filament rheostat is a simple matter. > That's why you NEVER, from an engineering standpoint, add > components that have negative impacts on other areas of the > system. The rheostat Rich "harps" about is a prime example of > something that can cause more problems than it cures, because it > "corrects" what is almost always a non-problem while adding > unreliablity and the potential for damaging human error. NEVER? Historically then, why has Harris, Gates, RCA, CSI, Brown-Boveri, Continental, BE all included a manual or automatically-driven rheostat in their final power tube designs? There's nothing special about how or where these companies decided to place the location of a simple rheostat and I've never seen (to my best recollection) a filamant rheostat cause other system problems. Yes, it's possible. But the risk is certaily worth the addition of the control. > The trend of amplifier design, in the low-tech world we are in, will be > to REMOVE customer controls...not add them. Especially when > they have the potential to do harm and are unlikely to do any good. Can't argue with you here. Look at the Alpha 87A, ACOM 2000, and solid-state HF amps. However, the cost of operator protection goes into relatively expensive protection circuits which can, in and of themselves fail. > > In the commercial world, $6 on a component is at least > > $12 on the ex-works price. In the case of a variable or > > preset control, where testing and adjustment is > > required, add another $5. These are the real costs you > > find in a production environment. Fine, call it $20 for the rheostat and a couple of high-quality Pomona Industries test point jacks and I'll still pay for it. > You forgot the meter and circuits needed, and underestimate the > time required to make sure the system is calibrated, as well as the > cost of failures in the additional parts (any one of which could > actually cause a tube failure). Again, let the outboard DVM or iron-vane meter be responsible for the accuracy. When I'm not setting filament voltage, I can use it for other ham radio domestic chores. > > So all of a sudden, our filament rheostat is costing $20 > > plus sales tax to the end user. Similar sort of add ons > > happen for step start, increased cooling for the tank > > circuit and so on. Very soon, you're talking of the $5k > > plus amplifier. Which is part of the explanation of why Huh? How did we go from a $20 rheostat to a $5K amplifier? > I did a cost estimate on adjustable filament voltage at one time, > and asked for statistical data from Eimac on their tube returns. > They said other than amps that run the filaments at 10-20% extra > voltage (Dentron and two other manufacturers) they saw virtually no > preventable filament failures. Such failures were "in the noise floor" > of the statistics. Unlike Rich, I trust what Eimac tells me. I don't believe its an issue of filamant "failure" or tube returns but one of reduced emission life. The addition of a simple rheostat to the power tube's filament circuit makes good engineering and economic sense. -Paul, W9AC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W0YR@aol.com Tue Feb 6 14:51:08 2001 From: W0YR@aol.com (W0YR@aol.com) Date: Tue, 6 Feb 2001 09:51:08 EST Subject: [AMPS] SB-221 STANDY SWITCH Message-ID: <48.111a63e1.27b1695c@aol.com> I just picked up a perfect SB-221 Heathkit Amp. I like it, however, I don't like the fact that when you switch it on, the B+ comes on with the filaments. I would like to be able to enable the B+ and antenna changeover relay together, so the filaments could remain lit but the amp brought on line only when needed. Any thoughts? -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Tue Feb 6 14:55:13 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Tue, 6 Feb 2001 14:55:13 -0000 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D808@excalibur.swindon.msl.mitel.com> Paul said: >Huh? How did we go from a $20 rheostat to a $5K amplifier? Extrapolation - the result of adding one feature after another. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Tue Feb 6 15:16:43 2001 From: philk5pc@tyler.net (Phil Clements) Date: Tue, 6 Feb 2001 09:16:43 -0600 Subject: [AMPS] SB-221 STANDY SWITCH References: <48.111a63e1.27b1695c@aol.com> Message-ID: <01cd01c0904f$d247a260$849086d0@phil> > > I just picked up a perfect SB-221 Heathkit Amp. I like it, however, I don't > like the fact that when you switch it on, the B+ comes on with the filaments. > I would like to be able to enable the B+ and antenna changeover relay > together, so the filaments could remain lit but the amp brought on line only > when needed. Any thoughts? > Invest your time and money in a step-start and the other glitch mods. I can't think of a single advantage of separate HV control. (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Wt8r@aol.com Tue Feb 6 15:23:06 2001 From: Wt8r@aol.com (Wt8r@aol.com) Date: Tue, 6 Feb 2001 10:23:06 EST Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <21.711d42c.27b170da@aol.com> In a message dated 2/6/01 7:08:45 AM Eastern Standard Time, Peter_Chadwick@mitel.com writes: > The other side of the coin > is that GI Joe in a fox hole somewhere in the back of beyond overseas, with > shells arriving all around him can't go to Walmart if he's stuck for a > hammer.... > > > That's how the costs build up for mil stuff, and that's why COTS (Commercial > Off > The Shelf) is popular in some quarters. > > Sorry to go on - I've had enough of dealing with mil procurement to last the > rest of my life.........when you're the sole source, it's a lot of grief you > don't need! > > 73 > > Peter G3RZP > ============================================================ Peter, You really DO understand the Military Procurement system. I worked for the Air Force for 30 years as an electronics engineer. I designed & built custom instrumentation systems to test new equipment that contractors were trying to sell to the Government. It was always more important that the paper work be filled out correctly than whether I got the part or not or how quickly. One bone-headed Major insisted that I order 12 parts, one at a time (cost $1.29 each), when processing the form alone cost approximately $75.00. Another time some woman didn't like the supplier that I had picked, so she told ME to find another supplier. And then the Senators are the first ones to point out the excess cost of such items. Cheers, Dave, WT8R -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Tue Feb 6 15:41:09 2001 From: philk5pc@tyler.net (Phil Clements) Date: Tue, 6 Feb 2001 09:41:09 -0600 Subject: [AMPS] SB-220: Operate/Standby Switch References: <3A7FBC9A.23462.2E94744@localhost> <00b501c0904c$2b661b00$6501a8c0@paulch> Message-ID: <01d301c09053$3b1cc380$849086d0@phil> > I don't believe its an issue of filamant "failure" or tube returns but one > of reduced emission life. The addition of a simple rheostat to the power > tube's filament circuit makes good engineering and economic sense. > > -Paul, W9AC Amen, Paul. We are prolonging emisson here. An added bonus of a resistor/rheostat in the primary of the filament transformer is a bit of inrush protection that is there all the time. In some of Henry's big commercial amps with multi- tapped filament transformers, a 10 ohm power resistor is inserted in series with one leg of the filament transformer primary to do just this. A cheap bit of insurance that I have incorporated into all of my amps. When the supply of NOS glass tubes is exhausted, spending a few bucks to protect a sizeable tube investment makes sense, unless one owns Richardson stock. (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From tony@uch.net Tue Feb 6 15:46:21 2001 From: tony@uch.net (CT HRD) Date: Tue, 6 Feb 2001 17:46:21 +0200 Subject: [AMPS] Pictures uploaded Message-ID: <005c01c09054$353cbf00$1d2928d4@Oll> To all my customers and just friends. Just uploaded the pictures of : 1. Special shipment containers/boxes for any CT Morse products : hand keys and paddles. 2. UT7CT holding a bunch of 4CX1600B tubes in his hands. 3. Several other pictures of the popular tubes... All can be located at http://www.dxham.com New services at www.dxham.com : Web Design/Banners 73 ! ------ CT Ham Radio Devices (CT HRD) Fine Range of Hand Keys & paddles Collectable Stuff. Svetlana & Other Russian Tubes. DX Shack Rentals tony@uch.net ICQ#19487420 Site : www.dxham.com + 380 472 455518 (home) + 380 67 4701622 (mobile) -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Tue Feb 6 15:50:36 2001 From: philk5pc@tyler.net (Phil Clements) Date: Tue, 6 Feb 2001 09:50:36 -0600 Subject: [AMPS] SB-220: Operate/Standby Switch References: <6CEB3A36096CD2119FEE00A0C9410EC201D7D807@excalibur.swindon.msl.mitel.com> Message-ID: <01df01c09054$8cb504e0$849086d0@phil> > >I've seen six cases of low cathode emission in the > >past 18 years in 8877's. In five of those cases, > >the filament systems were modified to reduce voltage > > and they missed by a few percent. That is why the wattmeter should be looked at when adjusting filament voltage...to make sure the emission is not being reduced. A lot of ham shacks I've seen have modest a.c. wiring with long runs back to the service entrance. The voltage sag must be taken into account....another reason to adjust with full suds cranked up. (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:05:25 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:05:25 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102061605.f16G5e927162@contesting.com> > >Tom says; > >>By far the biggest stress in amateur service is the >> constant thermal cycling of the filament > >That's where the rheostat comes in handy - assuming proper proportions, it >limits surge current. > not in the real world >Of course, so does a suitably designed surge limiting filament >transformer, but >that can be a bit more expensive. In the SB-220 and TL-922, the T/R orig. relay is too slow for T/R with modern radios.. >... cheers, Peter - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:05:30 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:05:30 -0800 Subject: [AMPS] SB-221 STANDY SWITCH Message-ID: <200102061605.f16G5g927172@contesting.com> > >I just picked up a perfect SB-221 Heathkit Amp. I like it, however, I don't >like the fact that when you switch it on, the B+ comes on with the >filaments. > I would like to be able to enable the B+ and antenna changeover relay >together, so the filaments could remain lit but the amp brought on line only >when needed. Any thoughts? > a waste of time. The 221 already has a I-limited fil. transformer that allows the filament to be switched off and on without worry. - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:05:23 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:05:23 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102061605.f16G5d927157@contesting.com> > >> 1.) There would have to be some reasonable assurance lack of a >> rheostat actually is causing a problem with tube life. That doesn't >> seem to be the case since almost 80% of tube failures are G/K >> shorts and the remaining percentage mostly due to loss of vacuum >> or voltage breakdown failures. > With 8877s, most of the failures have been from gold-sputtering. please see Figure 24 on Web site. >However, most commercial amps, including every commercial transmitter in the >AM/FM broadcast industry use a rheostat to control filament voltage. In >commercial applications, it's common practice to run a new tube, >(particularly metal/ceramic power tubes) at the manufacturer's specified >filament voltage for 500 hours of operation, then reduce the filament >voltage at or slightly above the point where the emission begins to drop >off. Is this directly related to tube failure? Maybe. Maybe not. But, >tube life can be greatly extended when using this method. Especially so with filament-type tubes. >It's a >well-settled fact that power tube life is substantially shortened when >operating a power tube above the manufacturer's recommended filament >voltage. In 20 years of commercial broadcasting as a V.P. of Engineering, I >can honestly say that I had never experienced an open filament due to >filamant over-voltage, but premature emission reduction can be always be >expected. For heater-type tubes, the problem with excessive heater voltage is that it causes barium migration to the grid. . >Going to the station's G.M. with the news that a 4CX20,000D has >to be replaced or rebuilt is never a pleasant experience. > >> 2.) If the rheostat was added, provisions would have to be made for >> monitoring voltage accurately. Most expensive panel meters are >> only 2% of FS anywhere on the scale, and to make that worse it >> would be driven by a rectifier and true-RMS filtering system that >> would be full of components with tolerances. By the time all is said >> and done, the $6 rheostat would add $100 of cost to the PA if you >> bought new parts (which commercially you have to do, unless you >> are someone who foolishly mixes in surplus parts) and would have >> to be hand calibrated. > >Forget the meter. Simply add two insulated/isolated test jacks to monitor >filamant voltage with a hand-held true R.M.S. DVM, or iron vane voltmeter. >Those of us that feel filamant voltage sampling is important will use it. >Those who don't aren't stuck with a precision $100 movement. > good point >> 4.) Even if you stopped some life reduction by allowing filament >> adjustment, the end result would be to add a certain number of >> hours to the tube life. It would not make the tube live forever, and >> very likely would not improve it a measurable amount in Amateur >> service. > >Perhaps, but nobody is asking the tube to live forever. I simply want to be >able to control the voltage to the tube if I desire so that my elevated 255 >VDC AC mains Whew > doesn't translate to 6.5V on a tube rated for 6.0 V. Let me >make the choice. A rheostat and front panel test points is all I need. I >realize that amateur service is not a 24/7 operation like that of >broadcasting, but the benefit can still be realized just like adding >step-start inrush protection. > amen >> 5.) Factually the easier you make it for someone to screw up or >> abuse the equipment, the more likely it will happen. There would be >> a reasonably large percentage of additional failure from component >> failures and customer abuse or errors. > >Any more factual than the presence of the load and plate tune controls on >the amp? I can find plently of positions to kill my amp with improper >tuning technique and excessive overdrive. To protect against these >conditions from the operater costs no less than a rheostat. Keeping the >adjutsable limits reasonable on a filament rheostat is a simple matter. > >> That's why you NEVER, from an engineering standpoint, add >> components that have negative impacts on other areas of the >> system. The rheostat Rich "harps" about is a prime example of >> something that can cause more problems than it cures, because it >> "corrects" what is almost always a non-problem while adding >> unreliablity and the potential for damaging human error. > >NEVER? Historically then, why has Harris, Gates, RCA, CSI, Brown-Boveri, >Continental, BE all included a manual or automatically-driven rheostat in >their final power tube designs? There's nothing special about how or where >these companies decided to place the location of a simple rheostat and I've >never seen (to my best recollection) a filamant rheostat cause other system >problems. Yes, it's possible. But the risk is certaily worth the addition >of the control. > >> The trend of amplifier design, in the low-tech world we are in, will be >> to REMOVE customer controls...not add them. Especially when >> they have the potential to do harm and are unlikely to do any good. > >Can't argue with you here. Look at the Alpha 87A, ACOM 2000, and >solid-state HF amps. However, the cost of operator protection goes into >relatively expensive protection circuits which can, in and of themselves >fail. > >> > In the commercial world, $6 on a component is at least >> > $12 on the ex-works price. In the case of a variable or >> > preset control, where testing and adjustment is >> > required, add another $5. These are the real costs you >> > find in a production environment. > >Fine, call it $20 for the rheostat and a couple of high-quality Pomona >Industries test point jacks and I'll still pay for it. > >> You forgot the meter and circuits needed, and underestimate the >> time required to make sure the system is calibrated, as well as the >> cost of failures in the additional parts (any one of which could >> actually cause a tube failure). > >Again, let the outboard DVM or iron-vane meter be responsible for the >accuracy. When I'm not setting filament voltage, I can use it for other ham >radio domestic chores. > >> > So all of a sudden, our filament rheostat is costing $20 >> > plus sales tax to the end user. Similar sort of add ons >> > happen for step start, increased cooling for the tank >> > circuit and so on. Very soon, you're talking of the $5k >> > plus amplifier. Which is part of the explanation of why > >Huh? How did we go from a $20 rheostat to a $5K amplifier? > any port in a storm. >> I did a cost estimate on adjustable filament voltage at one time, >> and asked for statistical data from Eimac on their tube returns. >> They said other than amps that run the filaments at 10-20% extra >> voltage (Dentron and two other manufacturers) they saw virtually no >> preventable filament failures. Such failures were "in the noise floor" >> of the statistics. Unlike Rich, I trust what Eimac tells me. > >I don't believe its an issue of filamant "failure" or tube returns but one >of reduced emission life. correctamundo - either from tungsten dicarbide loss (filament types) or from barium migration (heater types)) >The addition of a simple rheostat to the power >tube's filament circuit makes good engineering and economic sense. > For me, it indicates good engineering. cheers, Paul - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:05:27 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:05:27 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102061605.f16G5f927165@contesting.com> > >Tom said: > >>Oh sure! Let the guy use his handy $25 dollar VOM to set voltage! > >have you looked at the accuracy of these cheap digital voltmeters? The >ones I've >seen were remarkably good...with no RF around. > > > >I've seen six cases of low cathode emission in the > >past 18 years in 8877's. In five of those cases, > >the filament systems were modified to reduce voltage > > and they missed by a few percent. > >can you prove it was that? Did it repeat on the replacements? > >As a percentage of the number of 8877s made, that must be miniscule. > >Just to stir things up, what percentage of 8877s made >(not just in ham gear) have failed because of parasitics? > According to Mr. Rauch, 8877s can not oscillate. He has never explained why. see Figure 24 on my Web site. > cheers, Peter - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:05:28 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:05:28 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102061605.f16G5g927170@contesting.com> > >Hi Peter, > >My "spam" filter made me miss most of this, but I should add a few >comments. > Spam -- that which questions pontifications. >> Rich says: >> >> >Consider that the price of a 25w rheostat is under $6. > >Of course Rich always leaves a few things out. > >1.) There would have to be some reasonable assurance lack of a >rheostat actually is causing a problem with tube life. That doesn't >seem to be the case since almost 80% of tube failures are G/K >shorts and the remaining percentage mostly due to loss of vacuum >or voltage breakdown failures. > >2.) If the rheostat was added, provisions would have to be made for >monitoring voltage accurately. Most expensive panel meters are >only 2% of FS anywhere on the scale, and to make that worse it >would be driven by a rectifier and true-RMS filtering system that >would be full of components with tolerances. By the time all is said >and done, the $6 rheostat would add $100 of cost to the PA [chortle] >if you >bought new parts (which commercially you have to do, unless you >are someone who foolishly mixes in surplus parts) and would have >to be hand calibrated. > >3.) If you get past the above you have given someone, who's skill at >reading meters, eyesight, and common sense are unknown, ability >at the mere tweek of a knob to RUIN a tube quickly. You can bet >that person, even if he did something wrong, would demand a free >tube...or it could be a V31BB who actually rewired his transformers >for 200 volts (on a 240 volt main ) so he could run more power! > > >4.) Even if you stopped some life reduction by allowing filament >adjustment, the end result would be to add a certain number of >hours to the tube life. It would not make the tube live forever, and >very likely would not improve it a measurable amount in Amateur >service. > >5.) Factually the easier you make it for someone to screw up or >abuse the equipment, the more likely it will happen. There would be >a reasonably large percentage of additional failure from component >failures and customer abuse or errors. > The DTR2000 runs 5.9v on the 8877 heater. The max fil. V is 5.25. >> Yes. Which is why in a home brew amp, you'd fit one, >> without argument. > >Not me. None of my amps have rheostats for filaments. The reason >is simple. My line voltage varies from 241 volts to 252 volts from the >highest demand periods of summer to the lowest demand times in >winter, and I am in a rural area many miles from generating plants >and even HV transmission lines. I know folks who have wider fluctuations. ..... >Most tube failures are due to manufacturing defects NIH syndrome. >in the tubes, or >abuse. Virtually none are controllable and correctable failures. > gold-sputtering is a correctable problem. Use a parasitic suppressor with less Rp. Use a glitch resistor. >...... - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:18:53 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:18:53 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102061619.f16GJ5929226@contesting.com> > >> >I've seen six cases of low cathode emission in the >> >past 18 years in 8877's. In five of those cases, >> >the filament systems were modified to reduce voltage >> > and they missed by a few percent. > >That is why the wattmeter should be looked at when adjusting >filament voltage...to make sure the emission is not being reduced. only works with thoriated tungsten. - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:18:54 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:18:54 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102061619.f16GJ6929229@contesting.com> >Hi Peter, > >My "spam" filter made me miss most of this, but I should add a few >comments. > Spam filters can not stop other people from replying to the those who don't buy everything Tom says. . ...... - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From baycock@HIWAAY.NET Tue Feb 6 16:31:26 2001 From: baycock@HIWAAY.NET (Bill Aycock) Date: Tue, 06 Feb 2001 10:31:26 -0600 Subject: [AMPS] SB-220: Operate/Standby Switch In-Reply-To: <200102061605.f16G5f927165@contesting.com> Message-ID: <3.0.5.32.20010206103126.01b74210@HIWAAY.NET> Tom did NOT say that, and fig 24 says nothing about oscillation., merely overheating. Been there saw that, read that, Bill-W4BSG At 08:05 AM 2/6/01 -0800, you wrote: >> >According to Mr. Rauch, 8877s can not oscillate. He has never >explained why. see Figure 24 on my Web site. >> >cheers, Peter > >- Rich..., 805.386.3734, www.vcnet.com/measures. >end > - Bill Aycock --- Persimmon Hill Woodville, Alabama, US 35776 (in the N.E. corner of the State) W4BSG -- Grid EM64vr baycock@HiWAAY.net w4bsg@arrl.net -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Tue Feb 6 16:43:35 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Tue, 6 Feb 2001 16:43:35 -0000 Subject: No subject Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D80D@excalibur.swindon.msl.mitel.com> Quote from an add in the ham ads at QTH.com:- >and 1 Each 1 KW Variable Inductor for Class C >Linear Amplifiers, $ 35.00. This 'Class C Linear Amplifier' really must be something!!! 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:48:58 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:48:58 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102061649.f16GnA904527@contesting.com> > >Tom did NOT say that, Tom said that 8877s can not oscillate - which is why he uses no vhf suppressor on the AL-1500. >and fig 24 says nothing about oscillation., merely >overheating. The Eimac letter explains that gold sputtering is the result of oscillation. > >Been there saw that, read that, > apparently not. > >At 08:05 AM 2/6/01 -0800, you wrote: >>> >>According to Mr. Rauch, 8877s can not oscillate. He has never >>explained why. see Figure 24 on my Web site. >>> >>cheers, Peter >> >>- Rich..., 805.386.3734, www.vcnet.com/measures. >>end >> > >- >Bill Aycock --- Persimmon Hill > Woodville, Alabama, US 35776 > (in the N.E. corner of the State) > W4BSG -- Grid EM64vr > baycock@HiWAAY.net > w4bsg@arrl.net > >-- >FAQ on WWW: http://www.contesting.com/FAQ/amps >Submissions: amps@contesting.com >Administrative requests: amps-REQUEST@contesting.com >Problems: owner-amps@contesting.com > > - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 6 16:50:14 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 08:50:14 -0800 Subject: [AMPS] Re: Message-ID: <200102061650.f16GoP904852@contesting.com> > >Quote from an add in the ham ads at QTH.com:- > >>and 1 Each 1 KW Variable Inductor for Class C >>Linear Amplifiers, $ 35.00. > > >This 'Class C Linear Amplifier' really must be something!!! > chortle - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From RMcGraw@InfoAve.Net Tue Feb 6 18:29:39 2001 From: RMcGraw@InfoAve.Net (Bob & Linda McGraw K4TAX) Date: Tue, 06 Feb 2001 10:29:39 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch References: <6CEB3A36096CD2119FEE00A0C9410EC201D7D805@excalibur.swindon.msl.mitel.com> Message-ID: <3A804293.5DA7@infoave.net> In general: Once upon a time in my life, professionally, it was my job as part of a team to review engineering models & prototypes for the ability to be manufactured and used reliably by the end user. Later it turned to quality acceptance and quality assurance. I seem to recall something that was referred to as "rule of 10s". It went like this" If a $1.00 part was designed into a piece of equipment and the part was defective, the projected cost of $10.00 was required to replace it with a new part. If the $1.00 part was allowed to get through production and end up in a final product it then would cost $100.00 to replace it. (One must consider all the unpacking, re-packing, re-test of the production lot and etc. Then if the $1.00 part (from engineering) went all the way to the end user, it cost $1000.00 to replace it at the end user site. (Figure the cost of travel, lodging, meals and the Field Service Engineer to accomplish this task.) In the end, a poor design or poor selection of parts can get very very expensive not to mention a very unhappy end user. An yes, if the user can figure out a way to operate something incorrectly thus causing a failure....... they always will. I really don't think it's possible to "totally idiot proof" a design. I'm told that there are those that can damage an anvil just carrying it across the street. :-) 73 Bob K4TAX Peter Chadwick wrote: > > Tom says; > > >By far the biggest stress in amateur service is the > > constant thermal cycling of the filament > > That's where the rheostat comes in handy - assuming proper proportions, it > limits surge current. > > Of course, so does a suitably designed surge limiting filament transformer, but > that can be a bit more expensive. > > >provisions would have to be made for monitoring voltage > >accurately > > I assumed external metering, but point taken, especially on cost. > > Of course, there's the BBC(?) experience with the 4CX250B, showing that some > filament voltage reduction can help life. GW4FRX has chapter and verse on that, > and, I seem to remember, has published the info here on occasion. Whether, in > amateur service, you'd notice the difference is another matter...... > > The real cost of a component in a piece of gear can be quite high. I even > convinced purchasing on one occasion that a 22p cermet trim pot was cheaper than > a 3p carbon one, because 15% of the carbon ones broke or otherwise failed in the > test department - and it cost just 8 times as much as the component cost of the > cermet to replace the failed part. Even adjusting a preset in the factory costs > a lot of money. > > 73 > > Peter G3RZP > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From RMcGraw@InfoAve.Net Tue Feb 6 18:37:14 2001 From: RMcGraw@InfoAve.Net (Bob & Linda McGraw K4TAX) Date: Tue, 06 Feb 2001 10:37:14 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch References: <3A7FC662.3523.30F7DD6@localhost> Message-ID: <3A80445A.39A9@infoave.net> I agree with Tom on this. Bigger is not better in the case of filament transformer ratings. If the tube requires 10V at 10A then a transformer rated at 10V at 10A CCS, properly cooled, is acceptable. At the same time one must consider the IR loss between the transformer and the tube socket and any thermal rise due to restricted heat dissipation. Start up current limiting, if desired, should be installed on the primary side only. In my view, a 10V @ 20A or 30A transformer etc. is typically asking for a hosts of problems. Tom Rauch wrote: > > > >By far the biggest stress in amateur service is the > > > constant thermal cycling of the filament > > > > That's where the rheostat comes in handy - assuming proper > > proportions, it limits surge current. > > Of course, so does a suitably designed surge limiting filament > > transformer, but that can be a bit more expensive. > > Not really, a suitable current limiting transformer costs LESS than > a transformer that allows excessive starting current. You do have to > allow for temperature rise, however, and not box it in. > > > >provisions would have to be made for monitoring voltage > > >accurately > > > > I assumed external metering, but point taken, especially on cost. > > Oh sure! Let the guy use his handy $25 dollar VOM to set voltage! > > I've seen six cases of low cathode emission in the past 18 years in > 8877's. In five of those cases, the filament systems were modified > to reduce voltage and they missed by a few percent. > > 73, Tom W8JI > w8ji@contesting.com > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From RMcGraw@InfoAve.Net Tue Feb 6 18:55:32 2001 From: RMcGraw@InfoAve.Net (Bob & Linda McGraw K4TAX) Date: Tue, 06 Feb 2001 10:55:32 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch References: <3A7FBC9A.23462.2E94744@localhost> <00b501c0904c$2b661b00$6501a8c0@paulch> Message-ID: <3A8048A4.5CF0@infoave.net> Paul and company: Are we overlooking the fact that as a tube approaches it max useable freq., that the back bombardment of the cathode from electrons knocked loose from the anode does raise the cathode temperature. Hence the reason for reducing the heater voltage.......as I understand it. In this case, it's reasonable to reduce the heater voltage. It also makes for current limiting during startup. In 24/7 service the cycle on and off times are nil. In amateur service, and others, the cycle on and off times can be several times a day. F Y I: My 2M 8877 amp now has 8058 hrs on the tube. (I've put them all on there too.) The fil xfmr is a constant voltage, saturable core reactor rated at 5V at 10A CCS. No adjustment needed as the voltage stays well within the 5% of the required value. I realize that this may not be an acceptable method with higher power tubes, hence much higher currents for the heater. But for those applications, I much more prefer to use an adjustable autoformer on the primary side in place of a rheostat. 73 Bob K4TAX Paul Christensen wrote: > > > 1.) There would have to be some reasonable assurance lack of a > > rheostat actually is causing a problem with tube life. That doesn't > > seem to be the case since almost 80% of tube failures are G/K > > shorts and the remaining percentage mostly due to loss of vacuum > > or voltage breakdown failures. > > However, most commercial amps, including every commercial transmitter in the > AM/FM broadcast industry use a rheostat to control filament voltage. In > commercial applications, it's common practice to run a new tube, > (particularly metal/ceramic power tubes) at the manufacturer's specified > filament voltage for 500 hours of operation, then reduce the filament > voltage at or slightly above the point where the emission begins to drop > off. Is this directly related to tube failure? Maybe. Maybe not. But, > tube life can be greatly extended when using this method. It's a > well-settled fact that power tube life is substantially shortened when > operating a power tube above the manufacturer's recommended filament > voltage. In 20 years of commercial broadcasting as a V.P. of Engineering, I > can honestly say that I had never experienced an open filament due to > filamant over-voltage, but premature emission reduction can be always be > expected. Going to the station's G.M. with the news that a 4CX20,000D has > to be replaced or rebuilt is never a pleasant experience. > > > 2.) If the rheostat was added, provisions would have to be made for > > monitoring voltage accurately. Most expensive panel meters are > > only 2% of FS anywhere on the scale, and to make that worse it > > would be driven by a rectifier and true-RMS filtering system that > > would be full of components with tolerances. By the time all is said > > and done, the $6 rheostat would add $100 of cost to the PA if you > > bought new parts (which commercially you have to do, unless you > > are someone who foolishly mixes in surplus parts) and would have > > to be hand calibrated. > > Forget the meter. Simply add two insulated/isolated test jacks to monitor > filamant voltage with a hand-held true R.M.S. DVM, or iron vane voltmeter. > Those of us that feel filamant voltage sampling is important will use it. > Those who don't aren't stuck with a precision $100 movement. > > > 4.) Even if you stopped some life reduction by allowing filament > > adjustment, the end result would be to add a certain number of > > hours to the tube life. It would not make the tube live forever, and > > very likely would not improve it a measurable amount in Amateur > > service. > > Perhaps, but nobody is asking the tube to live forever. I simply want to be > able to control the voltage to the tube if I desire so that my elevated 255 > VDC AC mains doesn't translate to 6.5V on a tube rated for 6.0 V. Let me > make the choice. A rheostat and front panel test points is all I need. I > realize that amateur service is not a 24/7 operation like that of > broadcasting, but the benefit can still be realized just like adding > step-start inrush protection. > > > 5.) Factually the easier you make it for someone to screw up or > > abuse the equipment, the more likely it will happen. There would be > > a reasonably large percentage of additional failure from component > > failures and customer abuse or errors. > > Any more factual than the presence of the load and plate tune controls on > the amp? I can find plently of positions to kill my amp with improper > tuning technique and excessive overdrive. To protect against these > conditions from the operater costs no less than a rheostat. Keeping the > adjutsable limits reasonable on a filament rheostat is a simple matter. > > > That's why you NEVER, from an engineering standpoint, add > > components that have negative impacts on other areas of the > > system. The rheostat Rich "harps" about is a prime example of > > something that can cause more problems than it cures, because it > > "corrects" what is almost always a non-problem while adding > > unreliablity and the potential for damaging human error. > > NEVER? Historically then, why has Harris, Gates, RCA, CSI, Brown-Boveri, > Continental, BE all included a manual or automatically-driven rheostat in > their final power tube designs? There's nothing special about how or where > these companies decided to place the location of a simple rheostat and I've > never seen (to my best recollection) a filamant rheostat cause other system > problems. Yes, it's possible. But the risk is certaily worth the addition > of the control. > > > The trend of amplifier design, in the low-tech world we are in, will be > > to REMOVE customer controls...not add them. Especially when > > they have the potential to do harm and are unlikely to do any good. > > Can't argue with you here. Look at the Alpha 87A, ACOM 2000, and > solid-state HF amps. However, the cost of operator protection goes into > relatively expensive protection circuits which can, in and of themselves > fail. > > > > In the commercial world, $6 on a component is at least > > > $12 on the ex-works price. In the case of a variable or > > > preset control, where testing and adjustment is > > > required, add another $5. These are the real costs you > > > find in a production environment. > > Fine, call it $20 for the rheostat and a couple of high-quality Pomona > Industries test point jacks and I'll still pay for it. > > > You forgot the meter and circuits needed, and underestimate the > > time required to make sure the system is calibrated, as well as the > > cost of failures in the additional parts (any one of which could > > actually cause a tube failure). > > Again, let the outboard DVM or iron-vane meter be responsible for the > accuracy. When I'm not setting filament voltage, I can use it for other ham > radio domestic chores. > > > > So all of a sudden, our filament rheostat is costing $20 > > > plus sales tax to the end user. Similar sort of add ons > > > happen for step start, increased cooling for the tank > > > circuit and so on. Very soon, you're talking of the $5k > > > plus amplifier. Which is part of the explanation of why > > Huh? How did we go from a $20 rheostat to a $5K amplifier? > > > I did a cost estimate on adjustable filament voltage at one time, > > and asked for statistical data from Eimac on their tube returns. > > They said other than amps that run the filaments at 10-20% extra > > voltage (Dentron and two other manufacturers) they saw virtually no > > preventable filament failures. Such failures were "in the noise floor" > > of the statistics. Unlike Rich, I trust what Eimac tells me. > > I don't believe its an issue of filamant "failure" or tube returns but one > of reduced emission life. The addition of a simple rheostat to the power > tube's filament circuit makes good engineering and economic sense. > > -Paul, W9AC > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From RMcGraw@InfoAve.Net Tue Feb 6 19:10:21 2001 From: RMcGraw@InfoAve.Net (Bob & Linda McGraw K4TAX) Date: Tue, 06 Feb 2001 11:10:21 -0800 Subject: [AMPS] Re: References: <6CEB3A36096CD2119FEE00A0C9410EC201D7D80D@excalibur.swindon.msl.mitel.com> Message-ID: <3A804C1D.10A8@infoave.net> Neat trick. I'd like to see the circuit. yuck yuck 73 Bob K4TAX Peter Chadwick wrote: > > Quote from an add in the ham ads at QTH.com:- > > >and 1 Each 1 KW Variable Inductor for Class C > >Linear Amplifiers, $ 35.00. > > This 'Class C Linear Amplifier' really must be something!!! > > 73 > > Peter G3RZP > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From N6BUU@aol.com Tue Feb 6 17:53:46 2001 From: N6BUU@aol.com (N6BUU@aol.com) Date: Tue, 6 Feb 2001 12:53:46 EST Subject: [AMPS] Re:+ Message-ID: <5e.6d861c5.27b1942a@aol.com> In a message dated 02/06/2001 09:16:03 AM Pacific Standard Time, RMcGraw@InfoAve.Net writes: << > > This 'Class C Linear Amplifier' really must be something!!! > > 73 > > Peter G3RZP > >> there is something called a class "bc" linear, if i remember right. that has class c bias but the drive is made to vary only over the linear portion of the curve. hank -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From K4MO@carolina.rr.com Tue Feb 6 22:55:35 2001 From: K4MO@carolina.rr.com (K4MO) Date: Tue, 6 Feb 2001 17:55:35 -0500 Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? Message-ID: <002501c0908f$ea86cdc0$c9575d18@carolina.rr.com> I have just about collected all the parts to build my next project and I will soon be faced with the decision of how to switch bands with the final tank circuit. I see three options: 1. Use the EF Johnson 222-101 variable inductor that I've been saving for the last few years. I used a roller in my last large amp, chiefly do to the fact that I had it and it saved all the trouble of fiddling with taps and such. 2. Use a big strap wound inductor and large ceramic switch. I have the coil, but will need to locate a switch. 3. Use the aforementioned coil but switch it with relays, which I would still need to procure. This offers the advantage of being able to remote control the band change at some point in the future. I am hoping some of the more experienced builders can offer some opinions and suggestions regarding the technical merits or shortcomings of these three choices. Is one method or the other more subject to random parasitic oscillations? Is tank circuit heating more of an issue with one or the others? What other considerations do I need to ponder in this regard? I have looked through most of the archives and could find no previous discussion on Rollers verses Switches so any and all thoughts and ideas are welcome. Thanks & 73, Theo - K4MO www.qsl.net/k4mo -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From wc6w@juno.com Tue Feb 6 23:27:49 2001 From: wc6w@juno.com (Radio WC6W) Date: Tue, 06 Feb 2001 18:27:49 EST Subject: [AMPS] FS: Small Variacs Message-ID: <20010206.160754.24607.0.WC6W@juno.com> with apologies to General Radio, these are made by Superior Electric. In case anyone wants to transfer the heater/filament voltage adjustment discussion into practice, I have some variable transformers that may be of use: Powerstat -- Type 10 120V 1.25 A variable transformer, used, no knob or dial -- $15 Type 10B 120V 1.75 A variable transformer, used, with dial, no knob -- $20 These are both 3" diameter by about 2-1/2" deep not including the 1/4" diameter shaft. Plus shipping, if necessary, naturally Contact: Marv WC6W 310 649 3111 (reasonable hours Pacific Time please) or via return e-mail * ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From kt4ja@cfl.rr.com Tue Feb 6 23:32:32 2001 From: kt4ja@cfl.rr.com (Walter Dail) Date: Tue, 6 Feb 2001 18:32:32 -0500 Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? References: <002501c0908f$ea86cdc0$c9575d18@carolina.rr.com> Message-ID: <001f01c09095$17279210$6401a8c0@thunderbolt> Theo, I'd like to see the info posted to the reflector. It would be good to consider the pros and cons of a roller. I've been contemplating the same thing. I've got a roller in my Johnson Thunderbolt and it works OK. I guess as long as the inductor can handle the power and is cooled (at high freqs) it shouldn't be a problem. 73, Walter KT4JA ----- Original Message ----- From: "K4MO" To: Sent: Tuesday, February 06, 2001 5:55 PM Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? > > I have just about collected all the parts to build my next project and I > will soon be faced with the decision of how to switch bands with the final > tank circuit. I see three options: > > 1. Use the EF Johnson 222-101 variable inductor that I've been saving for > the last few years. I used a roller in my last large amp, chiefly do to the > fact that I had it and it saved all the trouble of fiddling with taps and > such. > > 2. Use a big strap wound inductor and large ceramic switch. I have the coil, > but will need to locate a switch. > > 3. Use the aforementioned coil but switch it with relays, which I would > still need to procure. This offers the advantage of being able to remote > control the band change at some point in the future. > > I am hoping some of the more experienced builders can offer some opinions > and suggestions regarding the technical merits or shortcomings of these > three choices. Is one method or the other more subject to random parasitic > oscillations? Is tank circuit heating more of an issue with one or the > others? What other considerations do I need to ponder in this regard? > > I have looked through most of the archives and could find no previous > discussion on Rollers verses Switches so any and all thoughts and ideas are > welcome. > > Thanks & 73, > Theo - K4MO > www.qsl.net/k4mo > > > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Wed Feb 7 00:08:44 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 16:08:44 -0800 Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? Message-ID: <200102070008.f1708u929497@contesting.com> > >I have just about collected all the parts to build my next project and I >will soon be faced with the decision of how to switch bands with the final >tank circuit. I see three options: > >1. Use the EF Johnson 222-101 variable inductor that I've been saving for >the last few years. The 222 is good for 15 out. > I used a roller in my last large amp, chiefly do to the >fact that I had it and it saved all the trouble of fiddling with taps and >such. > >2. Use a big strap wound inductor and large ceramic switch. I have the coil, >but will need to locate a switch. > >3. Use the aforementioned coil but switch it with relays, which I would >still need to procure. This offers the advantage of being able to remote >control the band change at some point in the future. > >I am hoping some of the more experienced builders can offer some opinions >and suggestions regarding the technical merits or shortcomings of these >three choices. Is one method or the other more subject to random parasitic >oscillations? No. Parasitic resonance exists before one gets to the tank inductor. cheers, Theo - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Wed Feb 7 00:13:05 2001 From: 2@vc.net (measures) Date: Tue, 6 Feb 2001 16:13:05 -0800 Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? Message-ID: <200102070013.f170DG929691@contesting.com> > >Theo, > I'd like to see the info posted to the reflector. It would be good to >consider the >pros and cons of a roller. I've been contemplating the same thing. I've got >a roller in my Johnson Thunderbolt and it works OK. I guess as long as the >inductor can handle the power and is cooled (at high freqs) it shouldn't be >a problem. > general coverage is an advantage. cheers, Walter. - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From w1nr@eecorp.com Wed Feb 7 00:35:01 2001 From: w1nr@eecorp.com (Mike McCarthy, W1NR) Date: Tue, 6 Feb 2001 19:35:01 -0500 Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? In-Reply-To: <002501c0908f$ea86cdc0$c9575d18@carolina.rr.com> Message-ID: Theo, A roller inductor will give you "general coverage" as well as being able to fine tune each band better than with fixed taps. However, there is an added circuit to adjust every time you change bands. I like the way Henry does it, switching in fixed capacitors for TUNE and a roller inductor and variable LOAD cap. If you plan on using relays in a tank circuit, you better plan on using vacuum relays. You will also still need a 10M coil hanging off of the roller inductor. The roller inductor probably won't have enough Q and surface area to keep the amp happy on 10 and 12 meters. As for preferences, one less adjustment when changing bands would be favored by me. Mike, W1NR -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W8JI@contesting.com Wed Feb 7 01:27:52 2001 From: W8JI@contesting.com (Tom Rauch) Date: Tue, 6 Feb 2001 20:27:52 -0500 Subject: [AMPS] SB-220: Operate/Standby Switch In-Reply-To: <01d301c09053$3b1cc380$849086d0@phil> Message-ID: <3A805E48.12524.560ED0B@localhost> > > I don't believe its an issue of filamant "failure" or tube returns > > but one of reduced emission life. The addition of a simple rheostat > > to the power tube's filament circuit makes good engineering and > > economic sense. > > > > -Paul, W9AC > > Amen, Paul. > We are prolonging emisson here. An added bonus of a resistor/rheostat > in the primary of the filament transformer is a bit of inrush > protection that is there all the time. Put all those tubes laying around that are perfectly good except for low emission in one pile. Put all the tubes with internal defects like broken welds, leaking seals, open filaments, grids touching cathodes, and on and on in another. Now use common sense. Factually, emission life is an issue when the tube is operated at 25% of its capability in uninterrupted commercial service. In amateur applications, its mostly something for people to talk about. 73, Tom W8JI w8ji@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Wed Feb 7 01:46:10 2001 From: philk5pc@tyler.net (Phil Clements) Date: Tue, 6 Feb 2001 19:46:10 -0600 Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? References: <200102070013.f170DG929691@contesting.com> Message-ID: <026d01c090a7$c0812080$849086d0@phil> . I've been contemplating the same thing. I've got > >a roller in my Johnson Thunderbolt and it works OK. I guess as long as the > >inductor can handle the power and is cooled (at high freqs) it shouldn't be > >a problem. > > > general coverage is an advantage. I don't know if you are planning on 160-10 meters, but I too like the way Henry does it. Their roller coils are ganged together so that the Pi and L coils track perfectly across the spectrum. The 4-K Ultra even had the vacuum tune C ganged to the coils. Only two knobs on the front..."tune" and "load." In the 3-K Ultra and 8-K Ultra, large door knob caps are switched with solenoids for the tune C, and the Pi and L coils are ganged to track. Another solenoid shorts out half of the Pi coil on 40 meters and above. (Henry coils are stationary with the roller on the inside allowing fixed taps on the outside.) I have had great luck with the large Johnson coils. Adequate band switches for 8-9 bands at a reasonable price are hard to come by. (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From wc6w@juno.com Wed Feb 7 04:03:27 2001 From: wc6w@juno.com (Radio WC6W) Date: Tue, 06 Feb 2001 23:03:27 EST Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? References: <002501c0908f$ea86cdc0$c9575d18@carolina.rr.com> Message-ID: <20010206.204308.8151.0.WC6W@juno.com> On Tue, 6 Feb 2001 17:55:35 -0500 "K4MO" writes: Hi Theo, >I have just about collected all the parts to build my next project and I >will soon be faced with the decision of how to switch bands with the final >tank circuit. I see three options: > >1. Use the EF Johnson 222-101 variable inductor that I've been saving for >the last few years. I used a roller in my last large amp, chiefly do to the >fact that I had it and it saved all the trouble of fiddling with taps and >such. Rollers work great. And they do seem to be the military HF amplifier's preferred component in this application. >2. Use a big strap wound inductor and large ceramic switch. I have the coil, >but will need to locate a switch. That's a good approach, too. Perhaps, better in the old days with only 5 bands... a mite crowded with today's assortment. >3. Use the aforementioned coil but switch it with relays, which I would >still need to procure. This offers the advantage of being able to remote >control the band change at some point in the future. I've looked at relays, in lieu of option #1 or #2, on several projects and, whether for a tuned input or output, they end up being just so much more... stuff... that they become ... inelegant. You didn't mention what power level you're considering but, just guessing from the 222 series coil, for an output tank you would need largish vacuum relays -- pricey and space consuming, too. Of course, relays are the only way to go if you need to frequency hop. :-) >I am hoping some of the more experienced builders can offer some opinions >and suggestions regarding the technical merits or shortcomings of these >three choices. Is one method or the other more subject to random parasitic >oscillations? Nope. The plate circuit up to the tune C and it's return to the cathode are the only tank item's concerned here. Is tank circuit heating more of an issue with one or the >others? Just depends on the wire size / cross section. You'll need a lot of strap to go to the switch(es) if you are going to do option #2 right -- score another point for the rollers. What other considerations do I need to ponder in this regard? To meet modern harmonic specs you'll need to use a Pi-L network, which implies a second roller coil or switch deck. That can become mechanically limiting with a switch as the two coils should be mounted at right angles. Depending on your output impedance, it may be more practical to switch (or relay) in an extra fixed coil for 160 rather than have a roller big enough to cover it. There is a lot of "space" between 80 and 160 where no ham bands will be created in our license times. If you use an SPDT arrangement to short out the 160 coil, then the switch/relay can also connect in some extra load C for 160. >I have looked through most of the archives and could find no previous >discussion on Rollers verses Switches so any and all thoughts and >ideas are welcome. I vaguely recall some... discussion... of the relative merits back in the late 2nd millennium, though I'm afraid I can't peg it closer than that for you. 73, Marv WC6W * ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From nospam4me@juno.com Wed Feb 7 04:32:36 2001 From: nospam4me@juno.com (nospam4me@juno.com) Date: Tue, 6 Feb 2001 20:32:36 -0800 Subject: [AMPS] beam "sweep" tube amplifiers Message-ID: <20010206.203238.-307233.2.nospam4me@juno.com> re: Beam "Sweep" tube amplifier circuits - Bill Smith has been asking about the Dentron and & Sevtlana conversion circuit related to the grid placement. A topic which I've been doing quite a bit of homework. Just my personal fondness for that old home brew circuit scrounged from TV set horizontal output sections years ago... - Sweep Tube Amplifiers are by no means new.. My collection of ARRL and Radio Handbooks show many construction articles on such layouts. Anyone building amplifiers can find Handbooks for rock bottom prices on Ebay. Handbooks are an excellent resource of tube amplifier circuits. - The only issue I take with most of the mentioned circuits is the "most practical" placement of required bias - grid connections. Here's what I've found works very well... - The cathode is DC grounded. I've found many common Handbook choke values which work fine. It depends on how many bands, a calculator and dip meter what values you might end up using. - Cathode drive is best applied through a classic pi tuned circuit. At the high end of HF near 28MHz, the tube side (of the pi) cap value often becomes the stray and tube input capacitance in many circuits. I've actually used different values of coaxial cable to adjust the circuit. The actual value depends on the tube... No tuned input means bad news in the output results. - Grid #1 is rf bypassed to ground, but fed a negative control bias through a choke. I've found this method much easier than a series high watt zener in the cathode path (the most common used in Dentron and Handbook layouts). Those larger value zeners are becoming pricey and are often the first item to fail in a "glitch event." Put a bumper sticker on your car "glitch happens".... - My most practical bias supply approach is to rectify, filter then multiply the heater winding, then apply it to the grid #1 circuit through a well bypassed resistive voltage divider. The advantage of this method is it's simplicity. It is also a layout that can be applied to other non sweep tube circuits should you like it enough. The "ground" end of the negative divider is "dc lifted" through a simple relay contact in standby which applies the full negative supply output to cut off cathode current in receive/standby mode. Should a circuit require a larger negative voltage, a separate supply can be built up with separate higher xmfr windings. It's a very simple approach for which I wish I could claim the source credit for... alas here's where the heat gets turned up. - I "liberated" the above circuit from an old Palomar 300a CB amplifier. Although the amplifier works well and has the 40 through 10 meter bands, it was sold as a two-stage CB amplifier. No ones trying to kid anyone here. But a practical circuit can be found in the most strange of places. Why not lift the "better circuit" and apply it to a legal application. That I did... enough said... - Grids 2 and 3 are tied to chassis, DC and RF ground. Zero Signal Anode current can be set by adjusting the Grid #1 bias supply resistor voltage divider values. - I've found this circuit layout works very well and appears to be much more stable than other layouts I've tried. Of course, some exciter "feed through" power appears in the output. Drive appears to be around 15% lower than the same circuit less grid #1 tied to ground with the G2&3 grids for similar outputs. My previous amps mention of grid #1 dissipation concerns are not a problem with this method. - Output tank Z is often very low... Handbooks often use a older method of tank coupling, but I can manage a pi tank with proper concerns in place. Dentron Re builders might have to "touch up" their tank circuits with the Newer Svetlanas in operation. - If you can stomach the trip over to www.cbtricks.com for a copy of the Palomar 300a circuit diagram, it's well worth a look when considering sweep tube bias methods. - Don't forget your parasitic suppression in the anode path. Used to be Sweep tubes were relative poor performers in higher VHF ranges, but that's changed in newer generation tubes with lower output capacitance. Metering in my last Dentron Rebuild was moved over to the negative side of the power supply, in the interest of safety. It's often well described in Handbooks. Good luck with your conversion or new EL-509/519 project. - cheers skipp nospam4me@juno.com - ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From steve@g8izy.freeserve.co.uk Wed Feb 7 08:13:57 2001 From: steve@g8izy.freeserve.co.uk (Steve Eldridge) Date: Wed, 7 Feb 2001 08:13:57 -0000 Subject: [AMPS] Fan motor capacitors Message-ID: <001801c090de$0b949440$2ba6883e@freeserve.co.uk> I've found the recent discussion on fan performance, pressures and flow rates very interesting and informative. My question concerns the capacitors that are necessary to run these fans on single-phase mains. I have several large(ish) fans, a couple of which specify a capacitor of 3.2 uF on the rating plate. The others don't mention the capacitance required, but start and seem to run OK on 3 uF. Is the capacitance needed just to kick the motor off in the right direction, or does it's value have any effect on the power that the motor produces when running? I have plenty of suitable caps and can increase/reduce capacitance in 1 uF steps. Sorry, but electric motor theory is not one of my best subjects! Thanks and 73 Steve G8IZY. -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Wed Feb 7 08:34:39 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Wed, 7 Feb 2001 08:34:39 -0000 Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D811@excalibur.swindon.msl.mitel.com> Theo says; >I have the coil, but will need to locate a switch. Fair Radio Sales (http://www.fairradio.com/index.html) have ex BC375 switches at $3.95 or 10 for $32. They are on their 'special offer' page. These are big 1p 6way 30 degree indexing types, and they'll handle lots of power, even though the Signal Corps only used them in a 100 watt transmitter! I've used them up at 3kV, and the contacts are good for about 15 amps. There was an article in CQ some 10 years ago about ganging them, but for a Pi-L, it might be easier to use a right angle drive so the coils can be at right angles. If you go for a roller, you'll really need two of them to form a Pi-L to meet the harmonic requirements - although unless Riley's men inspect you with a spectrum analyser, no-one on the air will probably ever notice if your harmonics are 30dB down instead of 40. If you don't use multiband antennas without a tuner, a pi network is probably OK in reality. The most satisfactory high power variable L I've come across is the technique where you wind a silver plated phosphor bronze strip from an insulated former to a metal drum. It can have the problem of being a bit high in stray capacity at the top end of the range, though. My biggest thing against suitable size roller coasters is availability of suitable mechanical drives for them. A 6 way switch is OK for 9 bands. If you calculate the Q variation resulting from using one value of L for each band of 28/24 MHz, 21/18MHz, 14/10MHz, it comes out as a 'not to worry' size number. That leaves 3 positions for 7, 3.5 and 1.8 MHz. With the price of those BC375 switches, you could have 4 of them - one for the input tuning cap padders for 160 and 80, one for the taps on the pi coil, one for the padders across the loading cap on 160 and 80, and one for the L network coil. Under those circumstance, it would probably be worthwhile unhooking the springs on some of the detent mechanisms to get the torque requirements down. Hope this helps. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Wed Feb 7 08:40:45 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Wed, 7 Feb 2001 08:40:45 -0000 Subject: [AMPS] beam "sweep" tube amplifiers Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D812@excalibur.swindon.msl.mitel.com> One point I found absolutely vital was a separate bias pot for each tube. For a given bias voltage, I've measured a plate current variation from 2.5 to 45 mA on sweep tubes - about twice the variation on 6146Bs - so especially if there's going to be grid current, bias derived from a low impedance source is necessary. If you don't bias them at all, you really need to make sure the tubes are fairly well matched, otehrwise you can find one tube doing all the work, and the linearity being poor. I've used 1kohm bias pots across 15 volts or so, but if I were doing it again, I'd use an op amp and power transistor to make a shunt regulator for each tube. Otherwise, I can't add to Skipp's comments. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Wed Feb 7 08:50:36 2001 From: 2@vc.net (measures) Date: Wed, 7 Feb 2001 00:50:36 -0800 Subject: [AMPS] Roller Inductors vs. Bandswitches ... which is best? Message-ID: <200102070850.f178ok921576@contesting.com> > >Theo, > A roller inductor will give you "general coverage" as well as being >able to fine tune each band better than with fixed taps. However, there >is an added circuit to adjust every time you change bands. I like the >way Henry does it, switching in fixed capacitors for TUNE and a roller >inductor and variable LOAD cap. If you plan on using relays in a tank >circuit, you better plan on using vacuum relays. You will also still >need a 10M coil hanging off of the roller inductor. The roller inductor >probably won't have enough Q and surface area to keep the amp happy on >10 and 12 meters. > As for preferences, one less adjustment when changing bands would be >favored by me. > 9 bands is a handful for a switch. . cheers, Mike - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Wed Feb 7 08:50:38 2001 From: 2@vc.net (measures) Date: Wed, 7 Feb 2001 00:50:38 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102070850.f178om921580@contesting.com> > >> > I don't believe its an issue of filamant "failure" or tube returns >> > but one of reduced emission life. The addition of a simple rheostat >> > to the power tube's filament circuit makes good engineering and >> > economic sense. >> > >> > -Paul, W9AC >> >> Amen, Paul. >> We are prolonging emisson here. An added bonus of a resistor/rheostat >> in the primary of the filament transformer is a bit of inrush >> protection that is there all the time. > >Put all those tubes laying around that are perfectly good except for >low emission in one pile. > gold-sputtering reduces emission. >Put all the tubes with internal defects like broken welds, leaking >seals, open filaments, grids touching cathodes, and on and on in >another. > >Now use common sense. > >Factually, emission life is an issue when the tube is operated at >25% of its capability in uninterrupted commercial service. In >amateur applications, its mostly something for people to talk about. > > When is Mr. Rauch going to tell us why the 8877 needs no VHF suppressor. Why did Henry Radio, Dentron and Alpha use a VHF suppressor in their 8877 amplifiers. ? - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Wed Feb 7 08:51:08 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Wed, 7 Feb 2001 08:51:08 -0000 Subject: [AMPS] Fan motor capacitors Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D813@excalibur.swindon.msl.mitel.com> Steve says: >Is the capacitance needed just to kick the motor >off in the right direction, or does it's value have any >effect on the power that the motor produces >when running? As usual, it all depends. Some motors use a centrifugal switch to switch the capacitor out when it has got to speed, so the cap is just there for starting. Usually, these caps are in the 20 - 100 mFd region, (at least for 50Hz/230v supplies) and are often electrolytics, since they're not in circuit long enough to get dangerously hot - unless the switch sticks..... Other split phase motors use a cap permanently in circuit. The torque is somewhat dependant on the value, because obviously, if it's too low, the current falls. If it's too big, then the phase angle shifts round. Typical values are in the 2 to 16 microfarad range - at least for 50Hz/230 volt circuits. Such caps used to be paper, often PCB impregnated, but these days, tend to be a synthetic film type. You need a capacitor that can handle the current, of course. I've had success in using quite small caps to reduce speed on fans, but you need to be careful because often the fan also cools the motor, and if you slow it too far, overheating results. Generally, the value is fairly non critical. I found the best way to slow a motor was to use an auto transformer. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From k7fm@teleport.com Wed Feb 7 10:19:46 2001 From: k7fm@teleport.com (Lamb) Date: Wed, 7 Feb 2001 02:19:46 -0800 Subject: [AMPS] Roller Inductor v. Bandswitch Message-ID: <003d01c090ef$7facfa00$c5071ad8@colinlam> One other possibility - which has not been mentioned - is a fairly simple approach. Ask yourself how many bands you will really use the amplifier on. In my case, I have about 10 amplifiers. All are bandswitched. I really use amplifiers only on 80 and 20 meters, and I have separate stations for both bands. Thus, even though my amplifiers are bandswitching, I never switch bands after the amplifier is installed in operation. It would have been much simpler to build an amplifier for a single band. Output could be a Pi-L, the rf choke would be optimized, rf layout would be greatly simplified with a very slight increase in efficiency and I would not have to worry about some visitor turning the bandswitch (since I really never check the tuning as I never move it). It is an excuse to build more amplifiers. The downside is that the market value of the amp is almost zero - but since I never sell anything I acquire anyway (except old cars), that should not be a big deal. Leave instructions on the inside of the cabinet to convert the big amp to cb after you go QRT and the significant other can come out ok despite losing someone who has coffee with her in the morning before retiring to the hamshack and then returns just in time for dinner. 73, Colin K7FM -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From r_wheel@yahoo.com Wed Feb 7 13:20:48 2001 From: r_wheel@yahoo.com (Roger Wheeler) Date: Wed, 7 Feb 2001 05:20:48 -0800 (PST) Subject: [AMPS] MLA 2500B Reservoir Capacitors Message-ID: <20010207132048.9680.qmail@web9504.mail.yahoo.com> Can anyone help me please? I need some 150uF 500V (3.25cms dia & 8 cms long) screw connector capacitors for my defunct Dentron Linear. am having some difficulting finding a supplier in the UK. G3MGW Roger __________________________________________________ Do You Yahoo!? Yahoo! Auctions - Buy the things you want at great prices. http://auctions.yahoo.com/ -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From wc6w@juno.com Wed Feb 7 16:36:40 2001 From: wc6w@juno.com (Radio WC6W) Date: Wed, 07 Feb 2001 11:36:40 EST Subject: [AMPS] ?: Rockwell Collins HF-8064B preselector Message-ID: <20010207.091617.7207.1.WC6W@juno.com> Hi, Does anyone on the group happen to know the remote control data format & pinout of the 55 pin interface connector for a Rockwell Collins HF-8064B preselector, a part of the HF-80 radio system? Or, perhaps, where I might come by a manual (or a copy) for same? 73, Marv WC6W P.S. -- I've already tried this query on the Collins group and fruitlessly searched the web. * ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From jtml@lanl.gov Wed Feb 7 16:42:20 2001 From: jtml@lanl.gov (John T. M. Lyles) Date: Wed, 7 Feb 2001 09:42:20 -0700 Subject: [AMPS] rheostats Message-ID: Paul, W9AC, is correct that many of the broadcast rigs in the US that use(d) air-cooled power tubes with handles and thoriated tungsten filaments have/had a rheostat to adjust it. If the rheostat is properly rated and not enclosed in a tiny chassis to overheat, it should do an excellent job. An occassional touch up of the setting is good to keep the wiper contact clean. Variacs, powerstats, are useful, but they too have a wiper that needs to be moved once in a while. Use of a current limited transformer is also used in many rigs, designed for a factor of 2 overcurrent. This takes care of the cold turnon transient current per the tube manufacturers specifications. Some systems also use a slow ramp up system to do this, and a conventional transformer. John K5PRO -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Wed Feb 7 16:45:30 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Wed, 7 Feb 2001 16:45:30 -0000 Subject: [AMPS] rheostats Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D81E@excalibur.swindon.msl.mitel.com> John, What do you use on your big amps? I would guess something slightly more sphisticated than a rheostat...... 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From kg7da@foxinternet.net Wed Feb 7 17:50:32 2001 From: kg7da@foxinternet.net (kg7da) Date: Wed, 7 Feb 2001 08:50:32 -0900 Subject: [AMPS] Tuned input for 2x8877 Message-ID: <003701c0912e$7b5a1c00$35c308d0@default> Anybody have values for hf amp 160-10 for tuned input network? Amp is bandswitched and switch is mounted. I know alpha built such a thing and there are a few homebrew ones out there too... tnx Marty -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Wed Feb 7 17:05:44 2001 From: 2@vc.net (measures) Date: Wed, 7 Feb 2001 09:05:44 -0800 Subject: [AMPS] rheostats Message-ID: <200102071705.f17H5s908600@contesting.com> > >Paul, W9AC, is correct that many of the broadcast rigs in the US that >use(d) air-cooled power tubes with handles and thoriated tungsten >filaments have/had a rheostat to adjust it. If the rheostat is >properly rated and not enclosed in a tiny chassis to overheat, it >should do an excellent job. An occassional touch up of the setting is >good to keep the wiper contact clean. Variacs, powerstats, are >useful, but they too have a wiper that needs to be moved once in a >while. During the Grate Parasitics Debate, sycophants from the Rauchian camp stated that a rheostat would not work. . cheers, John - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Wed Feb 7 17:09:00 2001 From: 2@vc.net (measures) Date: Wed, 7 Feb 2001 09:09:00 -0800 Subject: [AMPS] rheostats Message-ID: <200102071709.f17H99908918@contesting.com> > >John, > >What do you use on your big amps? I would guess something slightly more >sphisticated than a rheostat...... > Mo' complicated is not mo' betta. . - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Eric Moore" Hello, Does anybody have a Heathkit SA-2060 that they would like to sell? Or some other legal limit tuner? I am looking for something. 73, Eric K8CCA -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Wed Feb 7 17:11:36 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Wed, 7 Feb 2001 17:11:36 -0000 Subject: [AMPS] rheostats Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D821@excalibur.swindon.msl.mitel.com> Rich says: >Mo' complicated is not mo' betta. Maybe, but a rheostat for a tube with a 5kW filament is not the best way.......even if you're not in California where you can't waste that much power! 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From jtml@lanl.gov Wed Feb 7 17:21:29 2001 From: jtml@lanl.gov (John T. M. Lyles) Date: Wed, 7 Feb 2001 10:21:29 -0700 Subject: [AMPS] rheostats Message-ID: Reply to Peter Chadwick: Some of them use a motorized stack of variacs, 9 total, ganged with a driveshaft and chain drive. Three are in parallel per phase of 480 VAC, to handle the 75 amps per phase. The thing goes up in 90 seconds or so, then there is a 5 min. timer before HV can be energized. Others use smaller motorized variac stacks. My best filament system (I am proud of it) is using saturable reactor with a ramped DC supply on the control winding. It is good for a 250 kW tube filament, roughly 5 KVA at single phase 480 VAC 60 Hz. J -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ko4nrbs@yahoo.com Wed Feb 7 17:36:59 2001 From: ko4nrbs@yahoo.com (Bill Smith) Date: Wed, 7 Feb 2001 09:36:59 -0800 (PST) Subject: [AMPS] Plug In Power Supply Needed Message-ID: <20010207173659.27297.qmail@web4402.mail.yahoo.com> Does anyone have a plug in type power supply or small power cube 0-100 vdc they would sell? Bill -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Wed Feb 7 17:52:10 2001 From: philk5pc@tyler.net (Phil Clements) Date: Wed, 7 Feb 2001 11:52:10 -0600 Subject: [AMPS] Tuned input for 2x8877 References: <003701c0912e$7b5a1c00$35c308d0@default> Message-ID: <02d101c0912e$b62e88c0$849086d0@phil> > Anybody have values for hf amp 160-10 for tuned input network? Amp is > bandswitched and switch is mounted. > I know alpha built such a thing and there are a few homebrew ones out there > too... > > tnx > Marty Any Bill Orr or ARRL Handbook has a table with all the values shown. You need 50 ohms in and 25 ohms out. There is software on the disk you get with ARRL books that has a dandy program for designing pi networks. (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From harlins@swipnet.se Wed Feb 7 20:52:15 2001 From: harlins@swipnet.se (Lars Harlin) Date: Wed, 7 Feb 2001 21:52:15 +0100 Subject: SV: [AMPS] Roller Inductor v. Bandswitch References: <003d01c090ef$7facfa00$c5071ad8@colinlam> Message-ID: <003501c09147$dcae7460$f08897d4@default> Colin, Guess you hit the nail there! A very good approach and is'nt that what we all want to do, build and try more amps as the opposite to just discuss and argue about them. Compare to sex if you like... ;-) 73 de Lars/SM3BDZ ----- Ursprungligt meddelande ----- Från: Lamb Till: AMPS Skickat: den 7 februari 2001 11:19 Ämne: [AMPS] Roller Inductor v. Bandswitch > > One other possibility - which has not been mentioned - is a fairly simple > approach. Ask yourself how many bands you will really use the amplifier on. > > In my case, I have about 10 amplifiers. All are bandswitched. I really use > amplifiers only on 80 and 20 meters, and I have separate stations for both > bands. Thus, even though my amplifiers are bandswitching, I never switch > bands after the amplifier is installed in operation. > > It would have been much simpler to build an amplifier for a single band. > Output could be a Pi-L, the rf choke would be optimized, rf layout would be > greatly simplified with a very slight increase in efficiency and I would not > have to worry about some visitor turning the bandswitch (since I really > never check the tuning as I never move it). > > It is an excuse to build more amplifiers. > > The downside is that the market value of the amp is almost zero - but since > I never sell anything I acquire anyway (except old cars), that should not be > a big deal. Leave instructions on the inside of the cabinet to convert the > big amp to cb after you go QRT and the significant other can come out ok > despite losing someone who has coffee with her in the morning before > retiring to the hamshack and then returns just in time for dinner. > > 73, Colin K7FM > > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ccc@space.mit.edu Wed Feb 7 22:51:40 2001 From: ccc@space.mit.edu (Chuck Counselman) Date: Wed, 7 Feb 2001 17:51:40 -0500 Subject: [AMPS] WTB:Legal Limit Tuner In-Reply-To: <01d401c09128$f04384d0$29000101@windemullerelectric.com> Message-ID: Eric K8CCA wrote: >Does anybody have a Heathkit SA-2060 that they would like to sell? Or some >other legal limit tuner? >I am looking for something. I don't, but as the owner & user of a Heathkit SA-2500, which is the autotuning version of the SA-2060 (and which is not for sale), I'll say that it's an unusually robust tuner. I doubt that many so-called "legal limit" tuners are as good. -Chuck W1HIS -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Thu Feb 8 00:01:08 2001 From: 2@vc.net (measures) Date: Wed, 7 Feb 2001 16:01:08 -0800 Subject: [AMPS] rheostats Message-ID: <200102080001.f1801G927193@contesting.com> >Rich says: > >>Mo' complicated is not mo' betta. > >Maybe, but a rheostat for a tube with a 5kW filament is not the best >way.......even if you're not in California where you can't waste that much >power! > use transformer taps. > >Peter G3RZP > > > > - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From w2ge@home.com Thu Feb 8 01:51:23 2001 From: w2ge@home.com (Phil Levin W2GE) Date: Wed, 7 Feb 2001 20:51:23 -0500 Subject: [AMPS] WTB:Legal Limit Tuner In-Reply-To: Message-ID: I'm no expert, but I remember a review (QST???) and the Heathkit tuner was NOT very efficient, and they weren't very highly rated.... Phil W2GE -----Original Message----- From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On Behalf Of Chuck Counselman Sent: Wednesday, February 07, 2001 5:52 PM To: amps@contesting.com Subject: Re: [AMPS] WTB:Legal Limit Tuner Eric K8CCA wrote: >Does anybody have a Heathkit SA-2060 that they would like to sell? Or some >other legal limit tuner? >I am looking for something. I don't, but as the owner & user of a Heathkit SA-2500, which is the autotuning version of the SA-2060 (and which is not for sale), I'll say that it's an unusually robust tuner. I doubt that many so-called "legal limit" tuners are as good. -Chuck W1HIS -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ccc@space.mit.edu Thu Feb 8 03:32:57 2001 From: ccc@space.mit.edu (Chuck Counselman) Date: Wed, 7 Feb 2001 22:32:57 -0500 Subject: [AMPS] WTB:Legal Limit Tuner In-Reply-To: References: Message-ID: At 8:51 PM -0500 2001/2/7, Phil Levin W2GE wrote: >I'm no expert, but I remember a review (QST???) and the Heathkit tuner was >NOT very efficient, and they weren't very highly rated.... Phil, I'm e-mailing you off-list ('cuz they're .pdf files) the QST reviews of the two Heathkit tuners (model SA-2060A and SA-2500) that I downloaded from the Members Only product-review pages of the ARRL website. I don't remember any such negative statements. I'm also e-mailing you off-list the QST reviews of some other so-called "legal limit" tuners. These tuners got pretty critical (negative) reviews. Perhaps you're remembering them. Below are several reviews that I downloaded from , of the Heath model SA-2060A antenna tuner, which is the manual version of the automatic tuner (the model SA-2500) that I have. The RF components and their layout are the same, exactly the same as far as I can tell from pictures and spec's. Finally here's a review of the Heath SA-2040, which is like the SA-2060 except without 160 meters (i.e., limited to 80 through 10 meters), and without the built-in forward- and reflected-power meters. My model SA-2500 is connected to the 600-ohm balanced feedline of a center-fed wire that's almost a G5RV, and into which I put 1500 W on all legal bands from 80 through 10 meters (in other words, excluding 30 m and the novice sub-bands). My Heath tuner has never had any trouble with this power level on any of these bands, and my antenna is far from resonant on practically every band. -Chuck W1HIS "I moved some time ago and had my station in storage. I decided to get back on the air and went out and bought a Van Gorden G5RV Jr. [basically a commercially packaged version of what I have -C.] This was a cheap way to start operating again. I put the antenna up and tried to match it up with my old MFJ-901. [You know what I think of MFJ. -C.] What a joke. I could not get the SWR down below 2:1 except on 40 meters. I was rather angry, but remembered my old Heathkit tuner. This baby has been laying around for a long time. In fact, I had not used it after I put up a beam at my old QTH. I went to the closet and got it out dust and all. I decided to open it up to make sure that the caps and inductor were dust free. I hadn't seen the insides of this baby for at least ten years. Wow, she's built like a tank! I hooked the old girl up, and I can now tune 1:1 anywhere. This baby is solid and could handle a KW with ease. I would rate this tuner higher, but it does not have all the bells and whistles of more modern tuners, e.g., meters, switches and such." -N8JVL "Too bad these tuners are getting so hard to find. I guess the word is out on them and they are getting snatched up. If you can find one for under $200 in good condx, it's a bargain. I replaced a Nye MBV-A [one of the best regarded legal-limit tuners currently manufactured. -C.] with one of these, and have no regrets. It tunes smoothly and matches loads over a wide range very well. I have arced it, with an end-fed wire on 160m running my Alpha 89 [a legal-limit amp. -C.], but I'm not gonna hold that against it!... Heath really used quality components in this unit. You've got to spend a lot of money to match the performance of this veteran. And sometimes spending big bucks doesn't mean a superior product (the Nye MBV, for instance)." -K0RS "I bought this tuner in July of 1982 in kit form. I was very impressed with the quality of the inductor and capacitors.... In the almost 18 years of use it has worked trouble-free. At almost 18 years old I will continue to use it, and see no need to get a new one." -N0CGF "Not for Sale. I bought my SA-2060A just as Heath closed them out. I also use mine with the SB-1000 amp with just great performance. The roller inductor is top of the line unlike others on the market. So are the capacitors. No arcing problems with these. A friend picked up a mint one for $200 at Dayton. If you can find one, grab it and enjoy a top of the line product." -K3VO "when tuners were tuners... when quality was quality... no problems" -K2CF "Best Antenna Tuner Ever. What a beast of a tuner! Quality all the way. >From the silver plated straps and roller inductor to the solid copper sheet metal you just can't buy a better antenna tuner. Full legal limit plus. I have used my SA-2060A tuner for about 8 years now and it still looks new inside. No burns anywhere on anything. I have a Heathkit SB-1000 amplifer with the tuner sitting on top. I have never been able to make it arc or smoke running full-on with the amplifier. I currently run a 160 meter loop antenna with 450 ohm twin lead feed into the 4:1 balun inside the tuner and use it for all bands 160 to 10 meters." -N4ZOU -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ccc@space.mit.edu Thu Feb 8 03:38:19 2001 From: ccc@space.mit.edu (Chuck Counselman) Date: Wed, 7 Feb 2001 22:38:19 -0500 Subject: [AMPS] Big Dentron tuners In-Reply-To: References: Message-ID: Are the big Dentron tuners (e.g., the MT3000) still made? Available where? -Chuck W1HIS -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From da_kang@hotmail.com Thu Feb 8 19:34:37 2001 From: da_kang@hotmail.com (Jeff Wolf) Date: Thu, 08 Feb 2001 19:34:37 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: >In the commercial world, $6 on a component is at least >$12 on the ex-works price. Maybe in the Euro world, but here in the states, it doesn't. I work for the 2nd largest HVAC manufacturer in the world (nice, since high speed, high volume blowers are easy for me to procure :) ), and when we decided to go to wood pallets instead of using no pallets (just shrink-wrap 2 units together, and then use forks designed to pick up the piggybacked units) it cost the end user about a dollar more... >In the case of a variable or >preset control, where testing and adjustment is >required, add another $5. Not on our assembly line. Going to variable regulation on the new R12 replacement, it involved about 2 minutes per unit extended on the assembly line. This, passed on to the consumer, cost them nothing more. We where able to absolve it, and the conveyor speed system wasn't changed. Same thing on an amplifier. Maybe that is why European cars cost so much? They charge 12 dollars for a reostat, and 5 dollars for the tech to turn it? Use the same method Pride did on the DX-300/1KW unit. A small 3 prong receptacle on the back, with the reostat easily accessible, and you plug in a meter, and adjust the voltage to required. Takes me about 10 seconds to set the resting plate current on a DX-300 this way. I can't see it taking any more than that. >These are the real costs you >find in a production environment. In the words of George Carlin, NIMBY (not in my backyard) _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From richl@cyberdude.com Fri Feb 9 05:35:58 2001 From: richl@cyberdude.com (richl@cyberdude.com) Date: Thu, 08 Feb 2001 22:35:58 -0700 Subject: [AMPS] Dentron 160-10l Message-ID: <3A8381BE.8DCD01D5@cyberdude.com> Group, I am in need of a load and tune cap for a Dentron 160-10L amp that I am working on. Original ok but would prefer something that won't arc, but will drop in with out a lot of metal work. Please let me know where I can get something like this. Thanks in advance RichL KB7YEB -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Fri Feb 9 08:07:29 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Fri, 9 Feb 2001 08:07:29 -0000 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D830@excalibur.swindon.msl.mitel.com> Jeff says: >They charge 12 dollars for a reostat, and 5 dollars for >the tech to turn it? It all depends on how creative your accounting is at hiding real costs. A $6 rheostat has to be ordered by purchasing. It has to be unpacked and placed in stores. It has to be issued to the line and installed. It has to be adjusted, and there has suitable paperwork prepared to give test instructions/method. The invoice has to be reconciled with the delivery note, and the cheque and remittance advice raised. Even with maximum computersiation, that lot costs in time, and it adds up. Of course, you can short circuit these procedures - that's if you're not a quality firm that control what's happening. One thing I remember being told on the management course I did (before I decided to stick to engineering) is that in reality, unless you have a factory making only one product, you don't know how much each unit really costs. Even if you make only one product, it's difficult. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W8JI@contesting.com Fri Feb 9 16:21:48 2001 From: W8JI@contesting.com (Tom Rauch) Date: Fri, 9 Feb 2001 11:21:48 -0500 Subject: [AMPS] SB-220: Operate/Standby Switch In-Reply-To: <6CEB3A36096CD2119FEE00A0C9410EC201D7D830@excalibur.swindon.msl.mitel.com> Message-ID: <3A83D2CC.20551.12E0988D@localhost> Peter says: > A $6 rheostat has to be ordered by purchasing. It has to be unpacked > and placed in stores. It has to be issued to the line and installed. > It has to be adjusted, and there has suitable paperwork prepared to > give test instructions/method. The invoice has to be reconciled with > the delivery note, and the cheque and remittance advice raised. Even > with maximum computersiation, that lot costs in time, and it adds up. Then you have to add in cost of additional failures and problems caused by adding that rheostat, compared to what it might possibly help. And don't forget the internal metering (since you could NEVER depend on a random external meter). All this worry, planning, and expense to correct a non-problem is silly. 73, Tom W8JI w8ji@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Fri Feb 9 17:42:29 2001 From: philk5pc@tyler.net (Phil Clements) Date: Fri, 9 Feb 2001 11:42:29 -0600 Subject: [AMPS] SB-220: Operate/Standby Switch References: <3A83D2CC.20551.12E0988D@localhost> Message-ID: <003801c092bf$ae0d7420$ce9286d0@phil> > All this worry, planning, and expense to correct a non-problem is > silly. Modern amps now on the market are now not as much of a problem. Multi-tapped transformers and step-start circuits are incorporated in most designs. It is the old pre-1980 amps that need the attention. Most had no glitch protection, step-start, and only one "tap" on the transformer(s). They assumed that everyone had 115 or 230 volt mains. Most of the reports I have seen (including my own) indicate that 125/250 volt mains are becoming the norm in this country. To exasperate this problem, too many folks try to push these relics to 1500 watts + output when the components and cooling were chosen for much less. The cumulative effect will take its toll, sooner or later. (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From sm3jla@algonet.se Fri Feb 9 10:19:23 2001 From: sm3jla@algonet.se (Mikael Westerlund) Date: Fri, 9 Feb 2001 20:49:23 +1030 Subject: SV: [AMPS] SB-220: Operate/Standby Switch References: <3A83D2CC.20551.12E0988D@localhost> Message-ID: <001b01c09281$c65e9e20$70e7a3c3@py6lp> It can´t be that hard to calibrat whatever cheep meter you would like to use against an accurate one. Printing a new scale or just do some mark with a pencil. It need to be accurate within a very narow area of the scale. Mike SM3JLA ----- Ursprungligt meddelande ----- Från: Tom Rauch Till: Peter Chadwick ; ; <2@vc.net>; 'Jeff Wolf' ; Peter Chadwick Skickat: den 10 februari 2001 02:51 Ämne: RE: [AMPS] SB-220: Operate/Standby Switch > > Peter says: > > A $6 rheostat has to be ordered by purchasing. It has to be unpacked > > and placed in stores. It has to be issued to the line and installed. > > It has to be adjusted, and there has suitable paperwork prepared to > > give test instructions/method. The invoice has to be reconciled with > > the delivery note, and the cheque and remittance advice raised. Even > > with maximum computersiation, that lot costs in time, and it adds up. > > Then you have to add in cost of additional failures and problems > caused by adding that rheostat, compared to what it might > possibly help. And don't forget the internal metering (since you > could NEVER depend on a random external meter). > > All this worry, planning, and expense to correct a non-problem is > silly. > > > 73, Tom W8JI > w8ji@contesting.com > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Fri Feb 9 20:12:09 2001 From: 2@vc.net (measures) Date: Fri, 9 Feb 2001 12:12:09 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102092012.f19KCD909766@contesting.com> > >Peter says: >> A $6 rheostat has to be ordered by purchasing. It has to be unpacked >> and placed in stores. It has to be issued to the line and installed. >> It has to be adjusted, and there has suitable paperwork prepared to >> give test instructions/method. The invoice has to be reconciled with >> the delivery note, and the cheque and remittance advice raised. Even >> with maximum computersiation, that lot costs in time, and it adds up. > >Then you have to add in cost of additional failures and problems >caused by adding that rheostat, compared to what it might >possibly help. And don't forget the internal metering (since you >could NEVER depend on a random external meter). > Modern DMMs are fairly accurate. >All this worry, planning, and expense to correct a non-problem is >silly. > > Can anyone name the Henry Radio 3-500z amplifier that runs 6v on the filaments?. - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From sm3uzs@telia.com Fri Feb 9 21:05:34 2001 From: sm3uzs@telia.com (Johan Nordin) Date: Fri, 9 Feb 2001 22:05:34 +0100 Subject: [AMPS] Coax as an RF choke?? Message-ID: <003301c092dc$0c2e5f80$57cc143e@u61300209> Currently building a g-g amp on 2m with a GS35b There are several schematics floating around for this device including construction of RF chokes for filament and HT etc... I was thinking of making chokes of quarterwaves of thin coax, (grounded with respect to RF at the far end of the tube). Would like to try it at least as filament chokes instead of bifilar windings. The length of the cables will not be so long at VHF/UHF and it would be easy and quick to make theese RF chokes on any VHF/UHF frequency ( For thoose of us who are not familiar with calculations with the traditional designs). Just a thought, good or bad? Johan SM3UZS __________________________ Johan Nordin Omne 1444 S-870 30 Nordingra sm3uzs@telia.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From kc4slk@csrlink.net Fri Feb 9 21:27:09 2001 From: kc4slk@csrlink.net (Mike Sawyer) Date: Fri, 9 Feb 2001 16:27:09 -0500 Subject: [AMPS] SB-220: Operate/Standby Switch References: <3A83D2CC.20551.12E0988D@localhost> Message-ID: <006501c092df$118d2940$b379add1@kc4slk> All this worry, planning, and expense to correct a non-problem is silly. It isn't silly if you have a lot of money invested in a tube, (such as an 8877 et al), and your power line is prone to voltage fluctuations. How would you know with out a meter? I once had household line voltage at 135 VAC. My nickels worth...... Mike(y) W3SLK -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From RMcGraw@InfoAve.Net Sat Feb 10 01:13:06 2001 From: RMcGraw@InfoAve.Net (Bob & Linda McGraw K4TAX) Date: Fri, 09 Feb 2001 17:13:06 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch References: <3A83D2CC.20551.12E0988D@localhost> <006501c092df$118d2940$b379add1@kc4slk> Message-ID: <3A8495A2.5A5C@infoave.net> That's why I have a 5.0V secondary constant voltage transformer in my 8877 amp for the heaters. No meter needed. 73 Bob K4TAX Mike Sawyer wrote: > > All this worry, planning, and expense to correct a non-problem is > silly. > > It isn't silly if you have a lot of money invested in a tube, (such as an > 8877 et al), and your power line is prone to voltage fluctuations. How would > you know with out a meter? I once had household line voltage at 135 VAC. > My nickels worth...... > Mike(y) > W3SLK > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Ian White, G3SEK" References: <003301c092dc$0c2e5f80$57cc143e@u61300209> Message-ID: <25$bXYAqNIh6EAMh@ifwtech.plus.net> Johan Nordin wrote: > >Currently building a g-g amp on 2m with a GS35b > >There are several schematics floating around for >this device including construction of RF chokes >for filament and HT etc... >I was thinking of making chokes of quarterwaves of thin >coax, (grounded with respect to RF at the far end of the tube). >Would like to try it at least as filament chokes instead of >bifilar windings. >The length of the cables will not be so long at VHF/UHF >and it would be easy and quick to make theese RF chokes >on any VHF/UHF frequency ( For thoose of us who are not familiar >with calculations with the traditional designs). > >Just a thought, good or bad? Sure, it works fine. UT141 semi-rigid is OK at these currents, and you do not need a quarter-wave if you wind it into a coil. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.com/g3sek -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From carlseye@tampabay.rr.com Sat Feb 10 00:15:13 2001 From: carlseye@tampabay.rr.com (carl seyersdahl) Date: Fri, 9 Feb 2001 19:15:13 -0500 Subject: [AMPS] amps Message-ID: <005a01c092f6$89fc5740$8ea22041@tampabay.rr.com> Let's try a different subject for a moment. What real difference is there in the use of a shorting or non-shorting switch in the pi-network output of an amp?? Are there any real advantages one way or the other?? always wondered about it!! carl / kz5ca -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W8JI@contesting.com Sat Feb 10 00:55:52 2001 From: W8JI@contesting.com (Tom Rauch) Date: Fri, 9 Feb 2001 19:55:52 -0500 Subject: [AMPS] amps In-Reply-To: <005a01c092f6$89fc5740$8ea22041@tampabay.rr.com> Message-ID: <3A844B48.21108.14B74D39@localhost> Hi carl > in the use of a shorting or non-shorting switch in the pi-network > output of an amp?? Are there any real advantages one way or the > other?? always wondered about it!! carl / kz5ca These switches are called the wrong names all the time. A "shorting switch" picks up the next contact before releasing the one it was just on. It has less contact-to-contact holdoff voltage, and is a bad choice for this application. A shorting switch is normally used when switching isolated loads, where the moving contact (rotor) always has to be connected to something while rotating to prevent a failure of some type. xxxxx A "progressively-shorting" switch, or "pick-up-and-hold" switch progressively picks up contacts when rotated, and is a good switch to have. They can be ordered with either shorting or non-shorting type contacts. xxxxx A "non-shorting" switch rotor releases the stator contact fully before hitting the next stator contact. They generally have much higher contact-to-contact voltage ratings. They are used where the rotor has to fully drop a contact before connecting to the next one. They are often used to switch multiple power sources that can not be cross-connected. xxxxx The best switch for amplifier tanks is a non-shorting contact configuration using a pick-up-and-hold rotor. The reason you need the pick-up-and-hold rotor is because on higher bands the tank can have a self-resonance where it looks like two or four back-to-back L networks. If the voltage at the center of the L-networks formed by the stray capacitance and unshorted areas of inductor becomes high enough, the switch or other components will arc over and fail. The same problem occurs with *some* roller inductors, when a wide frequency range is covered, unless they have some form of additional shorting other than a single moving tap. 73, Tom W8JI w8ji@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From carlseye@tampabay.rr.com Sat Feb 10 01:39:49 2001 From: carlseye@tampabay.rr.com (carl seyersdahl) Date: Fri, 9 Feb 2001 20:39:49 -0500 Subject: [AMPS] switches Message-ID: <007801c09302$5d92e6e0$8ea22041@tampabay.rr.com> Tom: I've called many parts by the wrong names over the years, I guess. I was referring ,I guess, to the progressively shorting switch seen in so many amps today, as opposed to what I've seen in many construction articles, where they use what I would call a "break before make " type. Both types do essentially the same thing, IE. progressively shorting the tank coil turns. Other than the area of the switch contacts, I can't see much difference in the two setups although there might be some electronic reasoning behind them!! carl / kz5ca -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From phil@vaxxine.com Sat Feb 10 02:31:43 2001 From: phil@vaxxine.com (Phil (VA3UX)) Date: Fri, 09 Feb 2001 21:31:43 -0500 Subject: [AMPS] switches In-Reply-To: <007801c09302$5d92e6e0$8ea22041@tampabay.rr.com> Message-ID: <3.0.5.32.20010209213143.007a46f0@vaxxine.com> Tom, if I read Carl's original question properly, I think he was asking ' what is the electrical purpose of choosing a progressively shorting switch over one that isn't'. Carl : yes/no ? Phil At 08:39 PM 2/9/2001 -0500, carl seyersdahl wrote: > >Tom: I've called many parts by the wrong names over the years, I guess. I >was referring ,I guess, to the progressively shorting switch seen in so many >amps today, as opposed to what I've seen in many construction articles, >where they use what I would call a "break before make " type. Both types do >essentially the same thing, IE. progressively shorting the tank coil turns. >Other than the area of the switch contacts, I can't see much difference in >the two setups although there might be some electronic reasoning behind >them!! carl / kz5ca > > >-- >FAQ on WWW: http://www.contesting.com/FAQ/amps >Submissions: amps@contesting.com >Administrative requests: amps-REQUEST@contesting.com >Problems: owner-amps@contesting.com > > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W8JI@contesting.com Sat Feb 10 02:59:20 2001 From: W8JI@contesting.com (Tom Rauch) Date: Fri, 9 Feb 2001 21:59:20 -0500 Subject: [AMPS] switches In-Reply-To: <007801c09302$5d92e6e0$8ea22041@tampabay.rr.com> Message-ID: <3A846838.1261.15285A6F@localhost> Hi Carl, > Tom: I've called many parts by the wrong names over the years, I > guess. I was referring ,I guess, to the progressively shorting switch > seen in so many amps today, as opposed to what I've seen in many > construction articles, where they use what I would call a "break > before make " type. Both types do essentially the same thing, IE. > progressively shorting the tank coil turns. Other than the area of the > switch contacts, I can't see much difference in the two setups > although there might be some electronic reasoning behind them!! If you get a switch catalog you'll see the types explained. Even the Mouser catalog calls switches by the correct descriptions. If you order a "shorting switch" you get a simple one contact at a time switch that makes before breaking the previous connection. If you order a non-shorting, you get the same exact thing except the manufacturer reduces contact overhang and/or adds insulation so the moving contact drops before picking up the next contact. "Make-before-break" is another name for a "shorting switch". The above is vastly different than a "progressively shorting switch" which is also called a "pick-up-and-hold switch". Big difference between "shorting" and "pick-up-and-hold", totally different meanings and descriptions of operation. It isn't the switch manufacturers or catalogs who are using the wrong terms, hi hi. Amp Supply and Dentron used to actually order the wrong style switches, reducing contact-to-contact voltage breakdown, because the buyer didn't know the difference and didn't read the Centralab Catalog to find out the difference! 73, Tom W8JI w8ji@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From RMcGraw@InfoAve.Net Sat Feb 10 05:13:38 2001 From: RMcGraw@InfoAve.Net (Bob & Linda McGraw K4TAX) Date: Fri, 09 Feb 2001 21:13:38 -0800 Subject: [AMPS] switches References: <3.0.5.32.20010209213143.007a46f0@vaxxine.com> Message-ID: <3A84CE02.1B9A@infoave.net> Phil: I agree. Anyway, as I understand things, it's best to short the un-used turns out to prevent a high EMF on un-terminated taps and thus causing a flash-over or arc in the bandswitch. At the same time, I figured out that by doing so, shorting the turns, this created a "shorted turn" situation and some lost energy and heating would result. I guess it makes a difference which end is shorted. Short from the output to the input side of the coil or from the plate end toward the output. I'm sure someone can straighten me out on this. 73 Bob K4TAX Phil VA3UX wrote: > > Tom, if I read Carl's original question properly, I think he was asking ' > what is the electrical purpose of choosing a progressively shorting switch > over one that isn't'. Carl : yes/no ? > > Phil > > At 08:39 PM 2/9/2001 -0500, carl seyersdahl wrote: > > > >Tom: I've called many parts by the wrong names over the years, I guess. I > >was referring ,I guess, to the progressively shorting switch seen in so many > >amps today, as opposed to what I've seen in many construction articles, > >where they use what I would call a "break before make " type. Both types do > >essentially the same thing, IE. progressively shorting the tank coil turns. > >Other than the area of the switch contacts, I can't see much difference in > >the two setups although there might be some electronic reasoning behind > >them!! carl / kz5ca > > > > > >-- > >FAQ on WWW: http://www.contesting.com/FAQ/amps > >Submissions: amps@contesting.com > >Administrative requests: amps-REQUEST@contesting.com > >Problems: owner-amps@contesting.com > > > > > > > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ve3tu@rac.ca Sat Feb 10 10:26:12 2001 From: ve3tu@rac.ca (Steve) Date: Sat, 10 Feb 2001 10:26:12 +0000 Subject: [AMPS] switches References: <3.0.5.32.20010209213143.007a46f0@vaxxine.com> <3A84CE02.1B9A@infoave.net> Message-ID: <3A851744.6024EFDE@rac.ca> Hi yall, I believe that a switch that shorts out the unused taps on the tank cct. is the best way to go. The shorted coil in the tank next to the used tank portion will create a field that forces more of the circulating current to stay in the used tank portion, sort of like a shield. It also minimizes the Tesla effect on the higher bands and keeps the voltage down on the unused tank portion. I built the 8877 amp using Jerry's K8RA design which uses an air coil for 10M-40M and toriods on 80M and 160M. I had an arcing problem on 20M. I thought it was between the contacts of the band switch (Radio Switch model 88 non continuos shorting) but after closer examination I found it was arcing from the 40M tap on the switch to ground. That contact was at the bottom of the switch which made it difficult to see and looking at rf arcs is not the best thing for your eyes. The gap from the switch to ground is 3/4" so you can imagine the voltage present. I did some snooping using a NE2 neon bulb on a stick and found high current or voltage on the 80M toriod. I changed the phase on the 80M toriod and the arcing went away. Amps like the Commander use a continuos shorting switch which I believe helps clean up the signal by forcing more current to stay in the used tank coil. This just my opinion and some practical experience. gl es 73, Steve Bob & Linda McGraw K4TAX wrote: > Phil: I agree. > > Anyway, as I understand things, it's best to short the un-used turns out > to prevent a high EMF on un-terminated taps and thus causing a > flash-over or arc in the bandswitch. At the same time, I figured out > that by doing so, shorting the turns, this created a "shorted turn" > situation and some lost energy and heating would result. I guess it > makes a difference which end is shorted. Short from the output to the > input side of the coil or from the plate end toward the output. > > I'm sure someone can straighten me out on this. > > 73 > Bob K4TAX -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From gm3woj@talk21.com Sat Feb 10 11:14:09 2001 From: gm3woj@talk21.com (Chris Tran GM3WOJ) Date: Sat, 10 Feb 2001 11:14:09 -0000 Subject: [AMPS] 4CX1600B Message-ID: <000d01c09352$abd5f0e0$dab0fea9@chris.tran> Hello all I was going to modify a homebrew amp. to use a 4CX1600B (+SK3A base) but get the same message from 2 different suppliers "The 4CX1600B is not available in the U.S.A. at the moment" Does anyone know if there is a longer-term problem with supply of these tubes ? Thanks Chris GM3WOJ -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Sat Feb 10 12:10:05 2001 From: 2@vc.net (measures) Date: Sat, 10 Feb 2001 04:10:05 -0800 Subject: [AMPS] amps Message-ID: <200102101210.f1ACA6917193@contesting.com> > > Let's try a different subject for a moment. What real difference is there >in the use of a shorting or non-shorting switch in the pi-network output of >an amp?? Are there any real advantages one way or the other?? always >wondered about it!! carl / kz5ca > shorting switches prevents the tank coil from acting like a Tesla coil. - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Sat Feb 10 12:10:07 2001 From: 2@vc.net (measures) Date: Sat, 10 Feb 2001 04:10:07 -0800 Subject: [AMPS] SB-220: Operate/Standby Switch Message-ID: <200102101210.f1ACA8917198@contesting.com> > > > All this worry, planning, and expense to correct a non-problem is >silly. > > >It isn't silly if you have a lot of money invested in a tube, (such as an >8877 et al), and your power line is prone to voltage fluctuations. How would >you know with out a meter? you wouldn't. > I once had household line voltage at 135 VAC. >My nickels worth...... >Mike(y) >W3SLK > Ours dropped to c. 100v for 3 days. This is not ok for heater-type tubes - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From w2cqm@juno.com Sat Feb 10 12:47:37 2001 From: w2cqm@juno.com (w2cqm@juno.com) Date: Sat, 10 Feb 2001 07:47:37 -0500 Subject: [AMPS] Re: [Drake] SELL: Drake L4B Amplifier retrofitted for 6m Message-ID: <20010210.074835.-153367.1.w2cqm@juno.com> SELL: Absolutely mint conditioned (exterior) Drake L4B linear amplifier (serial # 2631) retrofitted and dedicated to 6 meter operation running a pair of Eimac 3-500's. Easily develops 1000++ watts OUTPUT with 80W of drive (200ma of grid current) in the SSB condition. All power supply and control circuitry is stock Drake except for the RF deck changes noted below and depicted on the digitals: a. parasitic chokes rewound b. HV plate choke rewound c. Dedicated 6 meter silvered, broad banded coil allows for 1 mHz DX chasing excursions without retuning. d. wide spaced, low capacitance plate tune air variable allows for smooth plate resonance tuning. e. moderate capacitance antenna tune air variable provides for smooth antenna matching f. "T" match exciter input control provides for extremely smooth tuning for "zero" SWR and maximum exciter drive. This is especially important today because of the often temperamental nature of the solid state rigs that shut themselves down. This control replaces the OEM bandswitch/coil assembly on the deck; however, careful attention was paid to the retrofit so that the amplifier does not appear to be modified in any way. The front panel is absolutely stock Drake (in appearance). Meter selection switch continues to monitor the full range of functions. No internal circuit changes were made to the power supply. The only alterations to the control panel are: a. Standby/operate switch functions normally but AGC removed. Rotates rather than push/pull. b. "T" match tuned exciter input control replaces the Drake bandswitch/coil assembly. The Drake RF deck chassis is absolutely perfect in all aspects. Paint is original Drake. There are no scratches, dings, or abrasions. The chassis interior is clean and bright with no smoke residue. There has been no "butchering" of the wiring. The L4PS matching power supply remains OEM Drake with no circuit changes. Only on careful examination the PS cabinet exhibits some barely visible blemishes on the top but there are no bangs or dents. The Drake quality control tag is still attached to the power cord. The package includes the original Drake manual. A schematic is provided outlining the basic mechanical changes. Troubleshooting is easy to accomplish using the Drake schematic because of the minimal circuit alterations. $1050. Prefer pickup in New York City or Scranton Pennsylvania area. Will be at Dayton ( Timonium??). Will consider shipping (reluctantly) at purchaser's expense provided a professional packer (mailboxes, etc.) does the final double boxing to ensure safe delivery. Ron W2CQM New York City http://homestead.juno.com/W2CQM/files/DRake6mpanel.jpg http://homestead.juno.com/W2CQM/files/Drake6mdeck.jpg Epilogue: See QRZ.COM for the listing of the most recent articles written for QST and 73 Magazine authored by W2CQM. http://www.qrz.com/callsign.html?callsign=w2cqm -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W8JI@contesting.com Sat Feb 10 13:39:38 2001 From: W8JI@contesting.com (Tom Rauch) Date: Sat, 10 Feb 2001 08:39:38 -0500 Subject: [AMPS] switches In-Reply-To: <3A84CE02.1B9A@infoave.net> Message-ID: <3A84FE4A.23251.1772AA00@localhost> > Anyway, as I understand things, it's best to short the un-used turns > out to prevent a high EMF on un-terminated taps and thus causing a > flash-over or arc in the bandswitch. At the same time, I figured out > that by doing so, shorting the turns, this created a "shorted turn" > situation and some lost energy and heating would result. I guess it > makes a difference which end is shorted. Short from the output to the > input side of the coil or from the plate end toward the output. The side you short on makes no difference at all. Current in the coil is essentially equal all through the coil, as long as the coil is not so large it acts like a transmission line or antenna or there aren't "shunting paths" that have low impedances compared to the coil. All inductors behave that way. Even loading coils. Two things save us from "great power loss" in the shorted turn area. First, the resistance in that shorted turn area is low compared to reactance. Second, the mutual coupling from the shorted turn area to the active area is not perfect. It always increases heat when we short sections of a tank coil (or loading coil), but the loss in power is usually insignificant. The real worry is heat, when a small amount of power loss is concentrated in a small area. If you eliminate the impedance of the leads to the switch with a coil that is marginal in size for the application, you will notice the increased heating even when you barely see a change in output power because all the heat is concentrated in a small area. Take a lug and wedge it between the turns of a miniductor coil that is a form having high mutual coupling between turns. The shorted turn will have low impedance, and resistance will be a significant part of current limiting. Mutual coupling effects make it a bad idea, in some cases, to progressively short a toroid. But most air-wound coils have so much flux leakage (and leads are so long) that shorting does not noticeably affect system loss. No matter what end you short, the effect is the same so far as circulating currents. 73, Tom W8JI w8ji@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From kc4slk@csrlink.net Sat Feb 10 15:17:49 2001 From: kc4slk@csrlink.net (Mike Sawyer) Date: Sat, 10 Feb 2001 10:17:49 -0500 Subject: [AMPS] 4CX1600B References: <000d01c09352$abd5f0e0$dab0fea9@chris.tran> Message-ID: <006001c09374$a52c30c0$e07aadd1@kc4slk> Chris, Check W4TH, Tom Hix's website: http://www.tomstubes.com/ or Tony, UT7CT site: http://www.dxham.com/. They would know how to hook you up with some 4CX1600B's. Gud Luck & 73, Mike(y) W3SLK ----- Original Message ----- From: "Chris Tran GM3WOJ" To: Sent: Saturday, February 10, 2001 6:14 AM Subject: [AMPS] 4CX1600B Hello all I was going to modify a homebrew amp. to use a 4CX1600B (+SK3A base) but get the same message from 2 different suppliers "The 4CX1600B is not available in the U.S.A. at the moment" Does anyone know if there is a longer-term problem with supply of these tubes ? Thanks Chris GM3WOJ -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From qrotec@bright.net Sat Feb 10 15:38:16 2001 From: qrotec@bright.net (QRO Technologies) Date: Sat, 10 Feb 2001 10:38:16 -0500 Subject: [AMPS] 4CX1600B References: <000d01c09352$abd5f0e0$dab0fea9@chris.tran> Message-ID: <001e01c09377$7e1e9a60$7a2b8fd1@oemcomputer> The 4CX1600B can be purchased through PM Components in the UK. They are the distributor for Svetlana in Europe. http://www.pmcomponents.co.uk 73's Ray Connin KB8VU ----- Original Message ----- From: "Chris Tran GM3WOJ" To: Sent: Saturday, February 10, 2001 6:14 AM Subject: [AMPS] 4CX1600B > > Hello all > > I was going to modify a homebrew amp. to use a > 4CX1600B (+SK3A base) but get the same message > from 2 different suppliers "The 4CX1600B is not > available in the U.S.A. at the moment" > > Does anyone know if there is a longer-term problem > with supply of these tubes ? > > Thanks > Chris GM3WOJ > > > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Sat Feb 10 16:04:11 2001 From: philk5pc@tyler.net (Phil Clements) Date: Sat, 10 Feb 2001 10:04:11 -0600 Subject: [AMPS] amps References: <200102101210.f1ACA6917193@contesting.com> Message-ID: <007301c0937b$1c84ce60$ce9286d0@phil> > > Let's try a different subject for a moment. What real difference is there > >in the use of a shorting or non-shorting switch in the pi-network output of > >an amp?? Are there any real advantages one way or the other?? always > >wondered about it!! carl / kz5ca > > > shorting switches prevents the tank coil from acting like a Tesla coil. > Amen, Rich! Been there, done that, got the T shirt! When 160 meters and WARC is added a whole new ball game evolves. It is very easy to arc even the heavy duty RF Switch Co. units with just a single 8877. Some designs get away with non-shorting switches by using torroids on 80 and 160 meters. Look at the schematics of the big Ameritron amps to see how the shorting is accomplished using coil stock for all bands. (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From tony@uch.net Sat Feb 10 16:11:25 2001 From: tony@uch.net (CT HRD) Date: Sat, 10 Feb 2001 18:11:25 +0200 Subject: [AMPS] 4CX1600B References: <000d01c09352$abd5f0e0$dab0fea9@chris.tran> Message-ID: <003401c0937c$23b70a80$342928d4@Oll> Hello, Chris, I have just ran out of 1999 Svetlana 4CX1600B. If you still need them - let me know. Also, you can have a look at me holding a bunch of the 4CX1600B tubes :-) http://www.dxham.com/images/ct%204cx1600b.jpg 73 ! -------- CT Ham Radio Devices (CT HRD) Fine Range of Hand Keys & paddles Collectable Stuff. Svetlana & Other Russian Tubes. DX Shack Rentals tony@uch.net ICQ#19487420 Site : www.dxham.com + 380 472 455518 (home) + 380 67 4701622 (mobile) ----- Original Message ----- From: Chris Tran GM3WOJ To: Sent: Saturday, February 10, 2001 1:14 PM Subject: [AMPS] 4CX1600B > > Hello all > > I was going to modify a homebrew amp. to use a > 4CX1600B (+SK3A base) but get the same message > from 2 different suppliers "The 4CX1600B is not > available in the U.S.A. at the moment" > > Does anyone know if there is a longer-term problem > with supply of these tubes ? > > Thanks > Chris GM3WOJ > > > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Sat Feb 10 16:23:03 2001 From: philk5pc@tyler.net (Phil Clements) Date: Sat, 10 Feb 2001 10:23:03 -0600 Subject: [AMPS] amps References: <3A844B48.21108.14B74D39@localhost> Message-ID: <00af01c0937d$bf59c3a0$ce9286d0@phil> > The same problem occurs with *some* roller inductors, when a > wide frequency range is covered, unless they have some form of > additional shorting other than a single moving tap. Check out how Henry handles this problem for continuous coverage 1.8-30 mhz in the 8-K and 3-K Ultras. (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From carlseye@tampabay.rr.com Sat Feb 10 20:22:47 2001 From: carlseye@tampabay.rr.com (carl seyersdahl) Date: Sat, 10 Feb 2001 15:22:47 -0500 Subject: [AMPS] switches References: <3.0.5.32.20010209213143.007a46f0@vaxxine.com> <3A84CE02.1B9A@infoave.net> Message-ID: <002f01c0939f$3bf3f220$8ea22041@tampabay.rr.com> Just got back from a hamfest, folks!! Phil, VA3UX seems to be the only one that understood my question correctly. both switches do the same thing so what's the electrical difference. if any in the use of switch or the other. carl / kz5ca ----- Original Message ----- From: "Bob & Linda McGraw K4TAX" To: "Phil VA3UX" Cc: "carl seyersdahl" ; "amps" Sent: Saturday, February 10, 2001 12:13 AM Subject: Re: [AMPS] switches > > Phil: I agree. > > Anyway, as I understand things, it's best to short the un-used turns out > to prevent a high EMF on un-terminated taps and thus causing a > flash-over or arc in the bandswitch. At the same time, I figured out > that by doing so, shorting the turns, this created a "shorted turn" > situation and some lost energy and heating would result. I guess it > makes a difference which end is shorted. Short from the output to the > input side of the coil or from the plate end toward the output. > > I'm sure someone can straighten me out on this. > > 73 > Bob K4TAX > > Phil VA3UX wrote: > > > > Tom, if I read Carl's original question properly, I think he was asking ' > > what is the electrical purpose of choosing a progressively shorting switch > > over one that isn't'. Carl : yes/no ? > > > > Phil > > > > At 08:39 PM 2/9/2001 -0500, carl seyersdahl wrote: > > > > > >Tom: I've called many parts by the wrong names over the years, I guess. I > > >was referring ,I guess, to the progressively shorting switch seen in so many > > >amps today, as opposed to what I've seen in many construction articles, > > >where they use what I would call a "break before make " type. Both types do > > >essentially the same thing, IE. progressively shorting the tank coil turns. > > >Other than the area of the switch contacts, I can't see much difference in > > >the two setups although there might be some electronic reasoning behind > > >them!! carl / kz5ca > > > > > > > > >-- > > >FAQ on WWW: http://www.contesting.com/FAQ/amps > > >Submissions: amps@contesting.com > > >Administrative requests: amps-REQUEST@contesting.com > > >Problems: owner-amps@contesting.com > > > > > > > > > > > > > -- > > FAQ on WWW: http://www.contesting.com/FAQ/amps > > Submissions: amps@contesting.com > > Administrative requests: amps-REQUEST@contesting.com > > Problems: owner-amps@contesting.com > > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From dbowker@mail.sjv.net Sat Feb 10 21:21:29 2001 From: dbowker@mail.sjv.net (Dave Bowker) Date: Sat, 10 Feb 2001 16:21:29 -0500 Subject: [AMPS] Amp Parts for Sale Message-ID: <003001c093a7$6ff19a20$cf98b7ce@dbowker> Send email request for list. 73, Dave, K1FK Fort Kent, ME -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From thomas.haglund@comtech-data.se Sat Feb 10 23:04:32 2001 From: thomas.haglund@comtech-data.se (thomas.haglund) Date: Sun, 11 Feb 2001 00:04:32 +0100 Subject: [AMPS] Message-ID: hello!,i am looking for internet sites with ALL possible info about amp building with tubes,i have been scanning the internet and found the usual sites but i need more! //SM7TVJ -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From kb7ww@chatusa.com Sun Feb 11 03:31:09 2001 From: kb7ww@chatusa.com (KB7WW Art Moe) Date: Sat, 10 Feb 2001 19:31:09 -0800 Subject: [AMPS] Metal Bending Calculator Message-ID: <3A86077D.9A187F9D@chatusa.com> Found this on line today and thought that those of you who build, or would like to build, your own chassis or cabinets might like it. It calculates "Bend Allowances" online. http://www.interl.net/~joemansh/smbc.html Art KB7WW -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From k4rv@mindspring.com Sun Feb 11 12:55:19 2001 From: k4rv@mindspring.com (Sain'T Tom) Date: Sun, 11 Feb 2001 06:55:19 -0600 Subject: [AMPS] tube type 100 watt 6 meter amp Message-ID: <005d01c09429$e4332160$af5ffc9e@oemcomputer> This is a multi-part message in MIME format. ------=_NextPart_000_005A_01C093F7.98B6DCE0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Anybody got a good, working 100 watt tube type 6 meter amplifier? If = so, I would like to see the schematic and layout. Please reply to k4rv@mindspring.com=20 Thanks Tom K4RV ------=_NextPart_000_005A_01C093F7.98B6DCE0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Anybody got a good, working 100 watt = tube type 6=20 meter amplifier? If so, I would like to see the schematic and=20 layout.

Please reply to=20 k4rv@mindspring.com

Thanks

Tom = K4RV

------=_NextPart_000_005A_01C093F7.98B6DCE0-- -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From vogler@innercite.com Sun Feb 11 14:50:08 2001 From: vogler@innercite.com (Bill Vogler) Date: Sun, 11 Feb 2001 14:50:08 +0000 Subject: [AMPS] 4CX1600B References: <200102110452.f1B4qT927580@contesting.com> Message-ID: <3A86A6A0.2F496D4E@innercite.com> Chris's original question of the long term supply situation of has not been answered. It appears that the channel of supply for both Tony and Tom is the surplus market (correct me if I am wrong). The next question that I have to ask from Ray's post that the 4cx1600b can be purchased through PM Components in the UK are these tubes new and being shipped from Svetlanta, or are they old stock? If these are old stock then there is clearly a problem with supply. If they are new stock then who in the US would want to have an amplifier that one has to go to the UK to buy a tube! There is clearly a problem going on with Svetlanta and the US operation. I personally know a ham that got laid off in the California branch office and he is not talking. He asked that his name not be used. Why did Svetlanta close their US office? Every one I talk to gives me a different answer to what is going on, not a good sign. I have the same question about long term supply of the 4cx1600b and it appears to be a tuff question to answer. 73s Bill, w6qd > Date: Sat, 10 Feb 2001 11:14:09 -0000 > From: "Chris Tran GM3WOJ" > Subject: [AMPS] 4CX1600B > > Hello all > > I was going to modify a homebrew amp. to use a > 4CX1600B (+SK3A base) but get the same message > from 2 different suppliers "The 4CX1600B is not > available in the U.S.A. at the moment" > > Does anyone know if there is a longer-term problem > with supply of these tubes ? > > Thanks > Chris GM3WOJ > Date: Sat, 10 Feb 2001 10:17:49 -0500 > From: "Mike Sawyer" > Subject: Re: [AMPS] 4CX1600B > > Chris, > Check W4TH, Tom Hix's website: http://www.tomstubes.com/ or Tony, UT7CT > site: http://www.dxham.com/. > They would know how to hook you up with some 4CX1600B's. > Gud Luck & 73, > Mike(y) > W3SLK > Date: Sat, 10 Feb 2001 10:38:16 -0500 > From: "QRO Technologies" > Subject: Re: [AMPS] 4CX1600B > > The 4CX1600B can be purchased through PM Components in the UK. They are the > distributor for Svetlana in Europe. http://www.pmcomponents.co.uk 73's Ray > Connin KB8VU > Date: Sat, 10 Feb 2001 18:11:25 +0200 > From: "CT HRD" > Subject: Re: [AMPS] 4CX1600B > > Hello, Chris, > > I have just ran out of 1999 Svetlana 4CX1600B. > > If you still need them - let me know. Also, you can have a look at me > holding a bunch of the 4CX1600B tubes :-) > http://www.dxham.com/images/ct%204cx1600b.jpg > > 73 ! -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From kt4ja@cfl.rr.com Sun Feb 11 15:26:51 2001 From: kt4ja@cfl.rr.com (Walter Dail) Date: Sun, 11 Feb 2001 10:26:51 -0500 Subject: [AMPS] 4CX1600B References: <200102110452.f1B4qT927580@contesting.com> <3A86A6A0.2F496D4E@innercite.com> Message-ID: <000801c0943f$123186a0$6401a8c0@thunderbolt> Just as I was considering building a homebrew amp using the 4CX1600B, this has come up. I hope this can be answered soon or I'll be looking at three 4CX800's instead. I would much rather use the '1600B, and deal with one tube and one socket, and a lot less sheet metal work. Walter - KT4JA ----- Original Message ----- From: "Bill Vogler" To: Sent: Sunday, February 11, 2001 9:50 AM Subject: [AMPS] 4CX1600B > > Chris's original question of the long term supply situation of has not > been answered. It appears that the channel of supply for both Tony and > Tom is the surplus market (correct me if I am wrong). The next question > that I have to ask from Ray's post that the 4cx1600b can be purchased > through PM Components in the UK are these tubes new and being shipped > from Svetlanta, or are they old stock? If these are old stock then there > is clearly a problem with supply. If they are new stock then who in the > US would want to have an amplifier that one has to go to the UK to buy a > tube! > > There is clearly a problem going on with Svetlanta and the US operation. > I personally know a ham that got laid off in the California branch > office > and he is not talking. He asked that his name not be used. Why did > Svetlanta close their US office? Every one I talk to gives me a > different answer to what is going on, not a good sign. > > I have the same question about long term supply of the 4cx1600b and it > appears to be a tuff question to answer. > > 73s > > Bill, w6qd > > > Date: Sat, 10 Feb 2001 11:14:09 -0000 > > From: "Chris Tran GM3WOJ" > > Subject: [AMPS] 4CX1600B > > > > Hello all > > > > I was going to modify a homebrew amp. to use a > > 4CX1600B (+SK3A base) but get the same message > > from 2 different suppliers "The 4CX1600B is not > > available in the U.S.A. at the moment" > > > > Does anyone know if there is a longer-term problem > > with supply of these tubes ? > > > > Thanks > > Chris GM3WOJ > > > Date: Sat, 10 Feb 2001 10:17:49 -0500 > > From: "Mike Sawyer" > > Subject: Re: [AMPS] 4CX1600B > > > > Chris, > > Check W4TH, Tom Hix's website: http://www.tomstubes.com/ or Tony, UT7CT > > site: http://www.dxham.com/. > > They would know how to hook you up with some 4CX1600B's. > > Gud Luck & 73, > > Mike(y) > > W3SLK > > > Date: Sat, 10 Feb 2001 10:38:16 -0500 > > From: "QRO Technologies" > > Subject: Re: [AMPS] 4CX1600B > > > > The 4CX1600B can be purchased through PM Components in the UK. They are the > > distributor for Svetlana in Europe. http://www.pmcomponents.co.uk 73's Ray > > Connin KB8VU > > > Date: Sat, 10 Feb 2001 18:11:25 +0200 > > From: "CT HRD" > > Subject: Re: [AMPS] 4CX1600B > > > > Hello, Chris, > > > > I have just ran out of 1999 Svetlana 4CX1600B. > > > > If you still need them - let me know. Also, you can have a look at me > > holding a bunch of the 4CX1600B tubes :-) > > http://www.dxham.com/images/ct%204cx1600b.jpg > > > > 73 ! > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From kt4ja@cfl.rr.com Sun Feb 11 17:29:39 2001 From: kt4ja@cfl.rr.com (Walter Dail) Date: Sun, 11 Feb 2001 12:29:39 -0500 Subject: [AMPS] 4CX1600B References: <200102110452.f1B4qT927580@contesting.com> <3A86A6A0.2F496D4E@innercite.com> <000801c0943f$123186a0$6401a8c0@thunderbolt> <000401c09444$fd803a20$2dfb7c3f@h1zc9> Message-ID: <001e01c09450$39c302f0$6401a8c0@thunderbolt> Dick, The only problem is that I wanted a tube that could be purchased "new" and not have to depend on the surplus market. For a surplus tube, the 4-1000 has been showing up at the local hamfests like candy! I did think about the 4CX1500B but the new price kept me away. The russian tubes are a lot cheaper! Later, Walter KT4JA ----- Original Message ----- From: "Dick Hanson" To: "Walter Dail" Sent: Sunday, February 11, 2001 11:09 AM Subject: Re: [AMPS] 4CX1600B > Walter.... > Good points. > Have you considered the 4CX1500B? There are many of these available new and > surplus. I don't know that I'd want to buy a new one as they are fairly > pricey, but you can frequently find "new" surplus ones for $125-200. You > then have to buy an SK-800B socket, or make one from Eimac parts found at > hamfests. I don't know if you go to Dayton, but all of this stuff available > there in quantity. A socket, used but clean, should cost about $50-100. > > Dick Hanson, K5AND EM74 > 7540 Williamsburg Dr. > Cumming, Ga. 30041 > 770-844-7002 home phone > 770-889-8297 home fax > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ik2ani@infinito.it Sun Feb 11 16:08:57 2001 From: ik2ani@infinito.it (Aldo Angeletti) Date: Sun, 11 Feb 2001 17:08:57 +0100 Subject: [AMPS] 2 x 813 linear amplifier on 160 m.: HELP! Message-ID: <000201c09459$90388fc0$fcbdd9d5@aldo> >From several years i'm working with my home made linear amplifier using a pair of 813 tubes. It works fine from 10 to 80 running about 500 to 700 watts output. Now I decide to make an attempt for the 160 m. So, following two similar articles (QST january 1989 pag. 23 and CQ november 1997 pag. 30), I add the additional capacitances on the legs of the PI-network and the additional inductance wounded on Amidon T225A iron core. I test with my grid dip the PI-network resonance frequency: it is 1850 Khz. WOW! However, when I turn on the amplifier the power output on 160 m band is only 300 watts!!! Why? Where is the mistake? Perhaps the RF choke on the plate? or the 500 pF capacitance (too small?) between the plates and the PI-network? or the Q of the additional inductance? Could you give me some suggestion to improve the performance and understand the reason why it does'n work as aspected? TNX and 73 de Aldo IK2ANI -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From wc6w@juno.com Mon Feb 12 00:20:27 2001 From: wc6w@juno.com (Radio WC6W) Date: Sun, 11 Feb 2001 19:20:27 EST Subject: [AMPS] FS: Ceramic Doorknob & Disk caps Message-ID: <20010211.165946.8151.0.WC6W@juno.com> FS: Ceramic Doorknob & Disk caps These are all made by Sprague, they are either NOS or little used. (Large) Doorknob style $15 ea 4000pF 30KV 3600pF 30KV 2500pF 30KV 2400pF 40KV 2000pF 30KV ----------------------- These are used Centralab or similar $5 ea 500pF 10KV "TV" style 1000pF 5KV 858 series 68pF 7.5KV 850 series Also available small quantities of several values in the 850 series in the 12-250pF range $5ea; inquire. ---------------------- These are NOS disks by KD & Erie $3ea or 4/$10 1500pF 7.5KV 2200pF 7.5KV .01uF 4KV All of the above plus shipping if necessary Contact: Marv WC6W 310 649 3111 (reasonable hours Pacific Time please) or via return e-mail * ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Mon Feb 12 09:49:52 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Mon, 12 Feb 2001 09:49:52 -0000 Subject: [AMPS] switches Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D83F@excalibur.swindon.msl.mitel.com> Tom's points are very interesting: I've always been accustomed to switches where you actually design them yourself on the templates provided by the manufacturer, so you can decide on make before break, as well as (in some types), fancy features such as insulated back contacts, short clips, dummy clips, etc. Non US readers note that the US terminology doesn't necessarily apply elsewhere, BTW. Of course, for home brew, it's a matter of what you can get. Using a 'progressively shorting' switch may not always be necessary: a straight forward 'break before make' wired to short out all the unused portion of coil, rather than all the taps on the coil, can work just as well. 'Progressively shorting' switches are of course limited in the number of positions available. One problem with rollers is if you need to short just a few turns at the end: they can then get very hot. I built one of the 'ultimate transmatch designs'; that had the problem on 160 of the last two turns overheating. Rewired so as not to short the unused portion, the strays and the unused L resonated at 14 MHz and arced over to chassis! Note Murphy working overtime........ Those switches from Fair Radio are a good bargain, although possibly marginal at 1500 watts. Cheap enough to keep a spare or two for if they do flash......although as the contacts are just hard copper sheet (as opposed to annealed), attached with 6-32 brass hardware, they're easily replaceable. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From sm5ki@algonet.se Mon Feb 12 11:50:48 2001 From: sm5ki@algonet.se (Hans Goldschmidt) Date: Mon, 12 Feb 2001 11:50:48 +0000 Subject: [AMPS] switches In-Reply-To: <6CEB3A36096CD2119FEE00A0C9410EC201D7D83F@excalibur.swindon.msl.mitel.com> Message-ID: 1-02-12 09.49, skrev Peter Chadwick på Peter_Chadwick@mitel.com följande: > > Tom's points are very interesting: I've always been accustomed to switches > where > you actually design them yourself on the templates provided by the > manufacturer, > so you can decide on make before break, as well as (in some types), fancy > features such as insulated back contacts, short clips, dummy clips, etc. Non > US > readers note that the US terminology doesn't necessarily apply elsewhere, BTW. > Of course, for home brew, it's a matter of what you can get. > > Using a 'progressively shorting' switch may not always be necessary: a > straight > forward 'break before make' wired to short out all the unused portion of coil, > rather than all the taps on the coil, can work just as well. 'Progressively > shorting' switches are of course limited in the number of positions available. > > One problem with rollers is if you need to short just a few turns at the end: > they can then get very hot. I built one of the 'ultimate transmatch designs'; > that had the problem on 160 of the last two turns overheating. Rewired so as > not > to short the unused portion, the strays and the unused L resonated at 14 MHz > and > arced over to chassis! > > Note Murphy working overtime........ > > Those switches from Fair Radio are a good bargain, although possibly marginal > at > 1500 watts. Cheap enough to keep a spare or two for if they do > flash......although as the contacts are just hard copper sheet (as opposed to > annealed), attached with 6-32 brass hardware, they're easily replaceable. > > 73 > > Peter G3RZP > > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > > Why use rollers and switches at all? Series tuning a coil varies the reactance, doesnt it? Has anybody tried to analyze if this is possible in a linear? I know WRL once made a ten tube compact linear usng this idea. Hans SM5KI -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Mon Feb 12 10:56:44 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Mon, 12 Feb 2001 10:56:44 -0000 Subject: [AMPS] switches Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D846@excalibur.swindon.msl.mitel.com> Hans said: >Series tuning a coil varies the reactance, doesnt it? To cover 80 through 10, you need roughly a 10 to one variation in inductance. However, the coil resistance stays the same, so the unloaded Q goes down at the 'low inductance' end - if everything else stays the same, it's reduced by a factor of 10. Further, because the inductive and capacitive reactances are high while the circulating current is (hopefully) the same as in the conventional case, the voltages are very large - so dielectric losses go up, too. Unless the series capacitor is big, you need a bigger inductor for the low end than is the case with the conventional approach. Not very practical........ 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From NICK.WALLACE@xtra.co.nz Mon Feb 19 18:13:06 2001 From: NICK.WALLACE@xtra.co.nz (NICK WALLACE) Date: Mon, 19 Feb 2001 18:13:06 -0000 Subject: [AMPS] Testing Message-ID: <002801c09aa0$05619520$566d36d2@default> This is a multi-part message in MIME format. ------=_NextPart_000_0024_01C09A9F.9B709C60 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Testing ------=_NextPart_000_0024_01C09A9F.9B709C60 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Testing

------=_NextPart_000_0024_01C09A9F.9B709C60-- -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From f5nga@mail.cpod.fr Mon Feb 19 09:06:30 2001 From: f5nga@mail.cpod.fr (f5nga) Date: Mon, 19 Feb 2001 10:06:30 +0100 Subject: [AMPS] TEST Message-ID: <001f01c09a53$407757a0$188127d4@cpod.fr.caen.cpod.fr> -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Mon Feb 19 13:04:31 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Mon, 19 Feb 2001 13:04:31 -0000 Subject: [AMPS] test Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D86A@excalibur.swindon.msl.mitel.com> -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Martin John Hallsworth" TEST TEST TEST -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From w2cqm@juno.com Sat Feb 17 18:53:53 2001 From: w2cqm@juno.com (w2cqm@juno.com) Date: Sat, 17 Feb 2001 13:53:53 -0500 Subject: [AMPS] Drake L4B Homebrewer Parts Package Message-ID: <20010217.135359.-256295.6.w2cqm@juno.com> SELL: a complete array of components for someone comtemplating a homebrew linear amplifier project but having difficulty locating the parts. The majority of the parts were carefully removed from a 10-80M Drake legal limit L4B and subsequently retrofitted for 6meters. The package consists of: 1. New Muffin Fan 2 & 4 Drake plate and antenna tune air variables w/plate tune shaft vernier and choke bypass 3 One piece bandswitch/coil combination ready to drop in. No RF burn marks, no cut wires. 5 Drake plate HV choke and parasitic choke(s) assembly with blocking caps 6 Drake pre-tuned fully adjustable tuned input circuit with cog and drive hardware for simultaneous input and bandswitching. Complete with coupling capacitor,and all coax. 7 New 3 minute 110VAC solid state timer relay 8 New (3) zener diodes 12VDC@10W 9 New 3P3T antenna changeover relay for legal limit ++ 10 Pair of 8877 (3CX1500A7) air system sockets with grid to ground tabs All of the components have been "surgically" removed from the Drake intact. There are no cut wires. The RF switch looks like new and has no burn marks on any contact. $285+ shipping Ron W2CQM New York City http://homestead.juno.com/w2cqm/files/RFDeckParts.JPG -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From k1ta@contesting.com Thu Feb 15 02:55:32 2001 From: k1ta@contesting.com (Bob Marston) Date: Wed, 14 Feb 2001 18:55:32 -0800 Subject: [AMPS] Test Message-ID: <3.0.6.32.20010214185532.007a6100@contesting.com> Is this thing working ? -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From dcckc@ncn.net Fri Feb 16 07:52:30 2001 From: dcckc@ncn.net (dcckc) Date: Fri, 16 Feb 2001 01:52:30 -0600 Subject: [AMPS] test Message-ID: <003701c097ed$70483e80$b23720cf@fatchance> sorry gentleman this is a test -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ccc@space.mit.edu Thu Feb 15 23:59:29 2001 From: ccc@space.mit.edu (Chuck Counselman) Date: Thu, 15 Feb 2001 18:59:29 -0500 Subject: [AMPS] Dayton blower motor Message-ID: I can't find any sign of an oil hole on the Dayton Mod 4C006B blower motor in my three-months-old Henry amp. What do you make of this? I don't recall seeing a motor this size (1/40 HP, IIRC) without oil holes. Ted Shannon (Henry) says that there should be arrows on the blower model-number label pointing to the oil holes. But there are no arrows on the model-number label on my motor. Is it possible that Dayton has begun making motors that don't need to be lubed by the user? I tried to find a Dayton website without success. -Chuck W1HIS -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From rjohnson@ici.net Sun Feb 18 18:12:07 2001 From: rjohnson@ici.net (Bob Johnson) Date: Sun, 18 Feb 2001 13:12:07 -0500 Subject: [AMPS] TEST-Please Delete Message-ID: -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From w2cqm@juno.com Sun Feb 18 01:46:10 2001 From: w2cqm@juno.com (w2cqm@juno.com) Date: Sat, 17 Feb 2001 20:46:10 -0500 Subject: [AMPS] sell: Drake L4B Components Message-ID: <20010217.204612.-185151.3.w2cqm@juno.com> SELL: a complete array of components for someone contemplating a homebrew linear amplifier project based on the Drake L4B amplifier circuitry but having difficulty locating the parts. The majority of the parts were carefully removed from a 10-80M Drake legal limit L4B that was subsequently retrofitted for 6meters. The package consists of: 1. New Muffin Fan 2 & 4 Drake plate and antenna tune air variables w/plate tune shaft vernier and choke bypass 3 One piece bandswitch/coil combination ready to drop in. No RF burn marks, no cut wires. 5 Drake plate HV choke and parasitic choke(s) assembly with blocking caps 6 Drake pre-tuned fully adjustable tuned input circuit with cog and drive hardware for simultaneous input tuning and bandswitching. Complete with coupling capacitor,and all coax. 7 New 3 minute 110VAC solid state timer relay 8 New (3) zener diodes 12VDC@10W 9 New 3P3T antenna changeover relay for legal limit ++ 10 Pair of 8877 (3CX1500A7) air system sockets with grid to ground tabs All of the components have been removed from the Drake intact. There are no cut wires! Everything will bolt up in its original alignment. The RF switch looks like new and has no burn marks on any contact. $285+ shipping Ron W2CQM New York City http://homestead.juno.com/w2cqm/files/RFDeckParts.JPG. -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ku7i@hotmail.com Sun Feb 18 00:09:35 2001 From: ku7i@hotmail.com (Lane Zeitler) Date: Sat, 17 Feb 2001 16:09:35 -0800 Subject: [AMPS] FS: commercial 3-500Z rf deck Message-ID: This is one of those unfinished projects. I picked up this RF deck around a year ago with the intent of getting it on the air but once again, too many irons in the fire so here it is.... Northern Radio Company (NRC) model N542 dual 3-500Z amp for sale. It is channelized in that you can select up to 6 different channels from the front panel. The operating range is 2-30 mhz and each channel covers a certain freq range, like 2-6, 6-12, etc. Not sure exactly of the freq range of each channel but you get the idea. It is in a 19 inch rack mountable chassis. There are three sides to this cabinet with the left side only partially there. This is not missing, this is actually how it is desgined. This thing is designed to slide into a 19 inch rack that is fully enclosed for added RFI protection. There are two handles on the front panel for grabbing the thing. There is one meter only and the range is 0 to 1.0. There is a meter select switch that allows you select Po, Ik, Vp, Ip. There is a channel select swith (rotary) that lets you select channels 1-6 and there is another rotary switch next to it that selects "local-remote". There is a power on/off switch with power on indicator light and a filament on/off switch with a filament power indicator light. The front panel is 15 1/2 " tall so you will need a tall cabinet to slide this into. Taller than the easy to get 75A4 cabinets. I have never applied power to this so it is being sold completely as-is. You will need to add a filament choke since the original was removed (not by me). The filament xmfr is part of this deck. This thing was originaly designed for commercial oil and cargo ships at sea and other than the B+ needs 120vac, single phase. Sorry, no documentation on it. The rf output pi-network uses a Pi-L. Looks like the main L in the o/p tank is the heavier B&W stock. The upper freq range of the coil uses 3/16" tubing. B&W model 800 plate choke. There are six seperate 4500 volt rated air variables, one for each band with the lowest having more pF than the highest. Not sure of the pF values but the caps are not that long, only around 4 inches. The tank selector switch is motorized. One RF input on the rear and six RF outputs, one for each band. Eimac SK-410 air system sockets installed (no chimneys). Also built into it is a Drake 3300 low pass filter. I am sorry that I do not have any picture available. There are a lot of RF doorknob caps in this, I count 16. There are six seperate air variables used in the loading side and most of the RF doorknobs are in parallel with these smaller air variables. The front panel is very nice, the underside of the chassis is super clean and there is some corrosion on the top side of the chassis but not terrible. I would like $125 for this plus actual shipping charges using UPS ground. I have a little more than this tied up into it but think that this is fair. My zip is 92139 and the weight is about 45 pounds. I would need a US Postal MO or certified bank check only. Lane Ku7i San Diego _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From phil@vaxxine.com Fri Feb 16 12:28:08 2001 From: phil@vaxxine.com (Phil (VA3UX)) Date: Fri, 16 Feb 2001 07:28:08 -0500 Subject: [AMPS] Riley Hollingsworth on Art Bell's show Message-ID: <3.0.5.32.20010216072808.007a8de0@vaxxine.com> Hollingsworth will be the main guest on Art Bell's show Next Thursday night, Feb 22nd. Should be interesting. Phil -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W0YR@aol.com Fri Feb 16 13:14:27 2001 From: W0YR@aol.com (W0YR@aol.com) Date: Fri, 16 Feb 2001 08:14:27 EST Subject: [AMPS] Creepy Amplifier Message-ID: <6b.ff01ab2.27be81b3@aol.com> AMP: Harris RF-110A (Pair of 4CX-1500Bs) PROBLEM: Plate current and power output creep up after about 15 seconds under "keydown" condition. The amplifier will "run away" with itself until the overloads kick in. Scenario: Amp is excited to about a kw output with carrier. Key down for 30 seconds. Power slowly increases to 1400 watts and would keep on increasing until the overloads kick it off. When I let up on the key, the idling current is high and then it slowly returns to its normal state. Have measured the grid bias, no change under "heat up conditions." Same for the zener regulated screen voltage supply. (I had thought the zeners were heating up and causing the screen voltage to rise, thus causing the increase in amplification. Apparently not so, no measurable increase in screen voltage.) I do not have extensive experience with ceramic tubes. Is this runaway output because of "soft" tubes? They REALLY put out. Or maybe it is thermal runaway, though the powerful air system on this military amp is working ok (and certainly makes enough noise). Under SSB conditions everything appears normal -- obviously due to the markedly lower duty cycle. Anybody got any ideas? Mike W0YR -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From phil@vaxxine.com Thu Feb 15 02:54:21 2001 From: phil@vaxxine.com (Phil (VA3UX)) Date: Wed, 14 Feb 2001 21:54:21 -0500 Subject: [AMPS] Riley Hollingsworth on Art Bell's show Message-ID: <3.0.5.32.20010214215421.00799210@vaxxine.com> Hollingsworth will be the main guest on Art Bell's show Next Thursday night, Feb 22nd. Should be interesting. Phil -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From fordgt390@yahoo.com Sun Feb 18 04:15:20 2001 From: fordgt390@yahoo.com (Mark) Date: Sat, 17 Feb 2001 20:15:20 -0800 (PST) Subject: [AMPS] test Message-ID: <20010218041520.29143.qmail@web11605.mail.yahoo.com> test __________________________________________________ Do You Yahoo!? Get personalized email addresses from Yahoo! Mail - only $35 a year! http://personal.mail.yahoo.com/ -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From W0YR@aol.com Fri Feb 16 18:58:13 2001 From: W0YR@aol.com (W0YR@aol.com) Date: Fri, 16 Feb 2001 13:58:13 EST Subject: [AMPS] Runaway amp Message-ID: --part1_bb.bca1b55.27bed245_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit AMP: Harris RF-110A (Pair of 4CX-1500Bs) PROBLEM: Plate current and power output creep up after about 15 seconds under "keydown" condition. The amplifier will "run away" with itself until the overloads kick in. Scenario: Amp is excited to about a kw output with carrier. Key down for 30 seconds. Power slowly increases to 1400 watts and would keep on increasing until the overloads kick it off. When I let up on the key, the idling current is high and then it slowly returns to its normal state. Have measured the grid bias, no change under "heat up conditions." Same for the zener regulated screen voltage supply. (I had thought the zeners were heating up and causing the screen voltage to rise, thus causing the increase in amplification. Apparently not so, no measurable increase in screen voltage.) I do not have extensive experience with ceramic tubes. Is this runaway output because of "soft" tubes? They REALLY put out. Or maybe it is thermal runaway, though the powerful air system on this military amp is working ok (and certainly makes enough noise). Under SSB conditions everything appears normal -- obviously due to the markedly lower duty cycle. Anybody got any ideas? Mike W0YR --part1_bb.bca1b55.27bed245_boundary Content-Type: message/rfc822 Content-Disposition: inline Return-Path: <> Received: from rly-ye03.mx.aol.com (rly-ye03.mail.aol.com [172.18.151.200]) by air-ye04.mail.aol.com (v77_r1.21) with ESMTP; Fri, 16 Feb 2001 12:17:33 -0500 Received: from paris.akorn.net (paris.akorn.net [216.1.128.10]) by rly-ye03.mx.aol.com (v77_r1.21) with ESMTP; Fri, 16 Feb 2001 12:17:04 -0500 Received: from localhost (localhost) by paris.akorn.net (8.11.0/8.11.0) id f1GH3lM06893; Fri, 16 Feb 2001 12:17:03 -0500 Date: Fri, 16 Feb 2001 12:17:03 -0500 From: Mail Delivery Subsystem Message-Id: <200102161717.f1GH3lM06893@paris.akorn.net> To: MIME-Version: 1.0 Content-Type: multipart/report; report-type=delivery-status; boundary="f1GH3lM06893.982343823/paris.akorn.net" Subject: Warning: could not send message for past 4 hours Auto-Submitted: auto-generated (warning-timeout) X-Mailer: Unknown (No Version) --f1GH3lM06893.982343823/paris.akorn.net ********************************************** ** THIS IS A WARNING MESSAGE ONLY ** ** YOU DO NOT NEED TO RESEND YOUR MESSAGE ** ********************************************** The original message was received at Fri, 16 Feb 2001 08:15:51 -0500 from imo-r02.mx.aol.com [152.163.225.2] ----- The following addresses had transient non-fatal errors ----- ----- Transcript of session follows ----- ... Deferred: Connection timed out with dayton.akorn.net. Warning: message still undelivered after 4 hours Will keep trying until message is 5 days old --f1GH3lM06893.982343823/paris.akorn.net Reporting-MTA: dns; paris.akorn.net Arrival-Date: Fri, 16 Feb 2001 08:15:51 -0500 Final-Recipient: RFC822; amps@contesting.com Action: delayed Status: 4.4.1 Remote-MTA: DNS; dayton.akorn.net Last-Attempt-Date: Fri, 16 Feb 2001 12:17:02 -0500 Will-Retry-Until: Wed, 21 Feb 2001 08:15:51 -0500 --f1GH3lM06893.982343823/paris.akorn.net Content-Type: message/rfc822 Return-Path: Received: from imo-r02.mx.aol.com (imo-r02.mx.aol.com [152.163.225.2]) by paris.akorn.net (8.11.0/8.11.0) with ESMTP id f1GDFp900963 for ; Fri, 16 Feb 2001 08:15:51 -0500 Received: from W0YR@aol.com by imo-r02.mx.aol.com (mail_out_v29.5.) id g.6b.ff01ab2 (664) for ; Fri, 16 Feb 2001 08:14:27 -0500 (EST) From: W0YR@aol.com Message-ID: <6b.ff01ab2.27be81b3@aol.com> Date: Fri, 16 Feb 2001 08:14:27 EST Subject: Creepy Amplifier To: amps@contesting.com MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Mailer: AOL 5.0 for Windows sub 129 AMP: Harris RF-110A (Pair of 4CX-1500Bs) PROBLEM: Plate current and power output creep up after about 15 seconds under "keydown" condition. The amplifier will "run away" with itself until the overloads kick in. Scenario: Amp is excited to about a kw output with carrier. Key down for 30 seconds. Power slowly increases to 1400 watts and would keep on increasing until the overloads kick it off. When I let up on the key, the idling current is high and then it slowly returns to its normal state. Have measured the grid bias, no change under "heat up conditions." Same for the zener regulated screen voltage supply. (I had thought the zeners were heating up and causing the screen voltage to rise, thus causing the increase in amplification. Apparently not so, no measurable increase in screen voltage.) I do not have extensive experience with ceramic tubes. Is this runaway output because of "soft" tubes? They REALLY put out. Or maybe it is thermal runaway, though the powerful air system on this military amp is working ok (and certainly makes enough noise). Under SSB conditions everything appears normal -- obviously due to the markedly lower duty cycle. Anybody got any ideas? Mike W0YR --f1GH3lM06893.982343823/paris.akorn.net-- --part1_bb.bca1b55.27bed245_boundary-- -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From w6ru@bak.rr.com Fri Feb 16 01:47:55 2001 From: w6ru@bak.rr.com (Terry Gaiser) Date: Thu, 15 Feb 2001 17:47:55 -0800 Subject: [AMPS] test Message-ID: <000a01c097ba$7bb7d3d0$6601a8c0@w6ruwin2000> This is a multi-part message in MIME format. ------=_NextPart_000_0007_01C09777.6D717B70 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable test ------=_NextPart_000_0007_01C09777.6D717B70 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

test

------=_NextPart_000_0007_01C09777.6D717B70-- -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From k6ndv@contesting.com Tue Feb 20 01:38:39 2001 From: k6ndv@contesting.com (Will Angenent) Date: Mon, 19 Feb 2001 17:38:39 -0800 Subject: [AMPS] Reflector mail Message-ID: There was a major crash at Contesting.com, no body had any mail from the reflector in the past week. Looks like things are back to normal. 73 Will, K6NDV administrator AMPS reflector -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From nospam4me@juno.com Tue Feb 20 02:40:39 2001 From: nospam4me@juno.com (nospam4me@juno.com) Date: Mon, 19 Feb 2001 18:40:39 -0800 Subject: [AMPS] it's back, but now on Ebay Message-ID: <20010219.184827.-327155.0.nospam4me@juno.com> - No one seemed to want that high quality 3-tube 4-1K amplifier on the yahoo auction site... so it's moved over to Ebay for your viewing pleasure. - THREE TUBE 4-1000 AMPLIFIER++++BIG TIME++++ Item #1214821045 - cheers skipp - ________________________________________________________________ GET INTERNET ACCESS FROM JUNO! Juno offers FREE or PREMIUM Internet access for less! Join Juno today! For your FREE software, visit: http://dl.www.juno.com/get/tagj. -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From rjohnson@ici.net Tue Feb 20 02:37:35 2001 From: rjohnson@ici.net (Bob Johnson) Date: Mon, 19 Feb 2001 21:37:35 -0500 Subject: [AMPS] TEST-Please Delete Message-ID: -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From rjohnson@ici.net Sun Feb 18 17:16:35 2001 From: rjohnson@ici.net (Bob Johnson) Date: Sun, 18 Feb 2001 12:16:35 -0500 Subject: [AMPS] TEST-Please Delete Message-ID: -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From K4MO@carolina.rr.com Tue Feb 20 03:41:58 2001 From: K4MO@carolina.rr.com (K4MO) Date: Mon, 19 Feb 2001 22:41:58 -0500 Subject: [AMPS] 813s & Sockets for sale Message-ID: <003401c09aef$13e4d900$c9575d18@carolina.rr.com> The following are for sale: Five JAN-813 (2 RCA, 2 Norelco, 1 Ken-Rad) with two ceramic 813 sockets - $75 for all including shipping - reply via email - Thanks! 73, Theo - K4MO www.qsl.net/k4mo -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From k1ta@contesting.com Tue Feb 20 04:10:25 2001 From: k1ta@contesting.com (Bob Marston) Date: Mon, 19 Feb 2001 20:10:25 -0800 Subject: [AMPS] Hello Hello Message-ID: <3.0.6.32.20010219201025.007ae250@contesting.com> Is this thing working ? -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From bjk@ihug.co.nz Tue Feb 20 04:31:16 2001 From: bjk@ihug.co.nz (Barry Kirkwood) Date: Tue, 20 Feb 2001 17:31:16 +1300 Subject: [AMPS] Hello Hello References: <3.0.6.32.20010219201025.007ae250@contesting.com> Message-ID: <030101c09af5$f7b25b20$a8d4adcb@ihug.co.nz> I was asking myself the same question! 73 end Barry Kirkwood PhD ZL1DD Signal Hill Homestay 66 Cory Road Palm Beach Waiheke Island 1240 NEW ZEALAND www.waiheke.co.nz/signal.htm ----- Original Message ----- From: Bob Marston To: Sent: Tuesday, 20 February, 2001 5:10 PM Subject: [AMPS] Hello Hello > > Is this thing working ? > > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Tue Feb 20 08:01:24 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Tue, 20 Feb 2001 08:01:24 -0000 Subject: [AMPS] switches Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D870@excalibur.swindon.msl.mitel.com> I sent this last week but it didn't get through. Tom says: >Back-to-back L nets can still form, causing extremely high >voltages in the tank, if that area of the coil is self-resonant >with stray C in the wiring and inductor(s). This is very true. It should be noted that both Tom and I said 'can', however, and not necessarily that the problem will occur. If it does happen, the difficulty I see is that you may get flash over in the tank switch - because of parasitic resonances rather than parasitic oscillations..... 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Peter_Chadwick@mitel.com Tue Feb 20 08:36:58 2001 From: Peter_Chadwick@mitel.com (Peter Chadwick) Date: Tue, 20 Feb 2001 08:36:58 -0000 Subject: [AMPS] Creepy Amplifier Message-ID: <6CEB3A36096CD2119FEE00A0C9410EC201D7D871@excalibur.swindon.msl.mitel.com> Mark said: >Have measured the grid bias, no change under "heat up conditions." I'd be inclined to suspect tubes producing some reverse grid current. However, have you measured the bias at the grid pin? (Put a series resistor or an RF Choke in series with the meter. A digital meter will get away with a series resistor, but may tell total lies with the RF applied. An old fashioned moving coil meter really needs a series RF Choke) It's possible that the resistance in the return from grid to bias to cathode has gone too high, and a smidgeon of reverse grid current can cause problems. It may be that getting the resistance in the grid as low as possible will allow the use of possibly dodgy tubes. One trick suggested for 4CX1000 s (which are rated for no grid current at all) is to use a diode to clamp across the grid feed resistor so as to prevent the grid showing signs of going positive under reverse grid current conditions. The reverse grid current could be due to gas, or it could be that some cathode material has sputtered over onto the grid. I surmise that if the tubes are fairly old and have seen a lot of service, this could happen. Worth checking if both tubes do it, or only one - pull each tube in turn. 73 Peter G3RZP -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From n4zr@contesting.com Tue Feb 20 12:35:02 2001 From: n4zr@contesting.com (Pete Smith) Date: Tue, 20 Feb 2001 07:35:02 -0500 Subject: [AMPS] hot switching on break Message-ID: <3.0.6.32.20010220073502.00815ec0@pop.gscyclone.com> >From what I have seen, the vacuum-relay QSK systems out there seem to spend most of their attention on speeding up the relays so that they will be fully closed before the RF arrives. Yet it seems to me that equal harm could be done on break, if RF is still present for any reason. Am I missing something? 73, Pete N4ZR Contesting is! The World Contest Station Database is waiting for your input at http://www.qsl.net/n4zr -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From drkirkby@ntlworld.com Tue Feb 20 13:03:27 2001 From: drkirkby@ntlworld.com (David Kirkby) Date: Tue, 20 Feb 2001 13:03:27 +0000 Subject: [AMPS] Creepy Amplifier References: <6b.ff01ab2.27be81b3@aol.com> Message-ID: <3A926B1F.11D06FC9@ntlworld.com> W0YR@aol.com wrote: > > AMP: Harris RF-110A (Pair of 4CX-1500Bs) > PROBLEM: Plate current and power output creep up after about 15 seconds under > "keydown" condition. > > The amplifier will "run away" with itself until the overloads kick in. > > Scenario: Amp is excited to about a kw output with carrier. Key down for 30 > seconds. Power slowly increases to 1400 watts and would keep on increasing > until the overloads kick it off. When I let up on the key, the idling > current is high and then it slowly returns to its normal state. > > Have measured the grid bias, no change under "heat up conditions." Same for > the zener regulated screen voltage supply. (I had thought the zeners were > heating up and causing the screen voltage to rise, thus causing the increase > in amplification. Apparently not so, no measurable increase in screen > voltage.) > > I do not have extensive experience with ceramic tubes. Is this runaway > output because of "soft" tubes? They REALLY put out. Or maybe it is thermal > runaway, though the powerful air system on this military amp is working ok > (and certainly makes enough noise). > > Under SSB conditions everything appears normal -- obviously due to the > markedly lower duty cycle. > > Anybody got any ideas? > > Mike > W0YR How much higher are we taling about - 1%, 10% 100% or whatever ? One possibility (I admit remote) is that the current is not actually increasing, but instead the meters shunts have got hot and therefore drift. I would not have thought there was any reason for an amp builder to run the shunts at anywhere near the point at which this would happen, but it is possible. Perhaps thermal movement in the tube causes one electrode to get nearer or further away from another and the resulting field changes causes this. Possible I'm sure, but that's all I could guess at. -- Dr. David Kirkby Ph.D, email: drkirkby@ntlworld.com former email address: davek@medphys.ucl.ac.uk web page: http://www.david-kirkby.co.uk Amateur radio callsign: G8WRB -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 20 15:34:04 2001 From: 2@vc.net (measures) Date: Tue, 20 Feb 2001 07:34:04 -0800 Subject: [AMPS] Runaway amp Message-ID: <200102201533.f1KFXbu07179@contesting.com> > AMP: Harris RF-110A (Pair of 4CX-1500Bs) > PROBLEM: Plate current and power output creep up after about 15 seconds >under > "keydown" condition. > > The amplifier will "run away" with itself until the overloads kick in. > > Scenario: Amp is excited to about a kw output with carrier. Key down for >30 > seconds. Power slowly increases to 1400 watts and would keep on increasing > until the overloads kick it off. When I let up on the key, the idling > current is high and then it slowly returns to its normal state. > > Have measured the grid bias, no change under "heat up conditions." Same >for > the zener regulated screen voltage supply. (I had thought the zeners were > heating up and causing the screen voltage to rise, thus causing the >increase > in amplification. Apparently not so, no measurable increase in screen > voltage.) > > I do not have extensive experience with ceramic tubes. Is this runaway > output because of "soft" tubes? They REALLY put out. Or maybe it is >thermal > runaway, though the powerful air system on this military amp is working ok > (and certainly makes enough noise). > > Under SSB conditions everything appears normal -- obviously due to the > markedly lower duty cycle. > > Anybody got any ideas? > > Mike > W0YR > > >Date: Fri, 16 Feb 2001 12:17:03 -0500 >From: Mail Delivery Subsystem >Subject: Warning: could not send message for past 4 hours > > > ********************************************** > ** THIS IS A WARNING MESSAGE ONLY ** > ** YOU DO NOT NEED TO RESEND YOUR MESSAGE ** > ********************************************** > >The original message was received at Fri, 16 Feb 2001 08:15:51 -0500 >from imo-r02.mx.aol.com [152.163.225.2] > > ----- The following addresses had transient non-fatal errors ----- > > > ----- Transcript of session follows ----- >... Deferred: Connection timed out with >dayton.akorn.net. >Warning: message still undelivered after 4 hours >Will keep trying until message is 5 days old > >Final-Recipient: RFC822; amps@contesting.com >Action: delayed >Status: 4.4.1 >Remote-MTA: DNS; dayton.akorn.net >Last-Attempt-Date: Fri, 16 Feb 2001 12:17:02 -0500 >Will-Retry-Until: Wed, 21 Feb 2001 08:15:51 -0500 > >From: W0YR@aol.com >Date: Fri, 16 Feb 2001 08:14:27 EST >Subject: Creepy Amplifier > > >AMP: Harris RF-110A (Pair of 4CX-1500Bs) >PROBLEM: Plate current and power output creep up after about 15 seconds >under >"keydown" condition. > >The amplifier will "run away" with itself until the overloads kick in. > AØ is not legal on HF. cheers - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 20 15:34:07 2001 From: 2@vc.net (measures) Date: Tue, 20 Feb 2001 07:34:07 -0800 Subject: [AMPS] switches Message-ID: <200102201533.f1KFXdu07184@contesting.com> > >I sent this last week but it didn't get through. > >Tom says: > >>Back-to-back L nets can still form, causing extremely high >>voltages in the tank, if that area of the coil is self-resonant >>with stray C in the wiring and inductor(s). > >This is very true. It should be noted that both Tom and I said 'can', >however, >and not necessarily that the problem will occur. If it does happen, the >difficulty I see is that you may get flash over in the tank switch - >because of parasitic resonances rather than parasitic oscillations..... > splitting hairs cheers > > > >-- >FAQ on WWW: http://www.contesting.com/FAQ/amps >Submissions: amps@contesting.com >Administrative requests: amps-REQUEST@contesting.com >Problems: owner-amps@contesting.com > > - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From 2@vc.net Tue Feb 20 15:34:09 2001 From: 2@vc.net (measures) Date: Tue, 20 Feb 2001 07:34:09 -0800 Subject: [AMPS] hot switching on break Message-ID: <200102201533.f1KFXfu07190@contesting.com> > >From what I have seen, the vacuum-relay QSK systems out there seem to spend >most of their attention on speeding up the relays so that they will be >fully closed before the RF arrives. Yet it seems to me that equal harm >could be done on break, if RF is still present for any reason. Am I >missing something? You are right. Break time must not interfere with the next make cycle. . pse see Figure 7 on my Web site. RY1 uses a diode & resistor across the coil to set break time on the output relay. . > cheers, Pete - Rich..., 805.386.3734, www.vcnet.com/measures. end -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ac6tk@cybertime.net Tue Feb 20 15:35:11 2001 From: ac6tk@cybertime.net (J. Bradshaw) Date: Tue, 20 Feb 2001 07:35:11 -0800 Subject: [AMPS] Hello Hello References: <3.0.6.32.20010219201025.007ae250@contesting.com> Message-ID: <009101c09b52$b75ca6e0$330c9bcf@eat> Is this thing working ? You gotta spit in the back, and give it a BIG WHUMP! -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Tue Feb 20 15:54:26 2001 From: philk5pc@tyler.net (Phil Clements) Date: Tue, 20 Feb 2001 09:54:26 -0600 Subject: [AMPS] Runaway amp References: Message-ID: <001c01c09b55$6987b240$0c9186d0@phil> > AMP: Harris RF-110A (Pair of 4CX-1500Bs) > PROBLEM: Plate current and power output creep up after about 15 seconds > under > "keydown" condition. > > The amplifier will "run away" with itself until the overloads kick in. > > Scenario: Amp is excited to about a kw output with carrier. Key down for 30 > seconds. Power slowly increases to 1400 watts and would keep on increasing > until the overloads kick it off. When I let up on the key, the idling > current is high and then it slowly returns to its normal state. Hi Mike, Look at the individual plate currents....is each rising the same? Look at the RF at the input to the amp....is it steady all the time? Will look in the manual today and see what I can figure out. (((73))) Phil, K5PC > Have measured the grid bias, no change under "heat up conditions." Same for > the zener regulated screen voltage supply. (I had thought the zeners were > heating up and causing the screen voltage to rise, thus causing the increase > in amplification. Apparently not so, no measurable increase in screen > voltage.) > > I do not have extensive experience with ceramic tubes. Is this runaway > output because of "soft" tubes? They REALLY put out. Or maybe it is > thermal > runaway, though the powerful air system on this military amp is working ok > (and certainly makes enough noise). > > Under SSB conditions everything appears normal -- obviously due to the > markedly lower duty cycle. > > Anybody got any ideas? > > Mike > W0YR > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From w1nr@eecorp.com Tue Feb 20 16:08:24 2001 From: w1nr@eecorp.com (Mike McCarthy, W1NR) Date: Tue, 20 Feb 2001 11:08:24 -0500 Subject: [AMPS] hot switching on break In-Reply-To: <3.0.6.32.20010220073502.00815ec0@pop.gscyclone.com> Message-ID: All rigs I have ever seen never release the amp relay until RF has ceased. Many use the same relay to key the amp and switch from TX to RX. Mike, W1NR -----Original Message----- From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On Behalf Of Pete Smith Sent: Tuesday, February 20, 2001 7:35 AM To: amps@contesting.com Subject: [AMPS] hot switching on break >From what I have seen, the vacuum-relay QSK systems out there seem to spend most of their attention on speeding up the relays so that they will be fully closed before the RF arrives. Yet it seems to me that equal harm could be done on break, if RF is still present for any reason. Am I missing something? 73, Pete N4ZR Contesting is! The World Contest Station Database is waiting for your input at http://www.qsl.net/n4zr -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From gdaught6@leland.stanford.edu Tue Feb 20 16:21:13 2001 From: gdaught6@leland.stanford.edu (George T. Daughters) Date: Tue, 20 Feb 2001 08:21:13 -0800 Subject: [AMPS] 3cv1500 Message-ID: <200102201619.f1KGJJp28187@smtp.Stanford.EDU> Hi, Now that the server is back (THANKS!!) I'll repost my request, which I thought had gone to the big 50 ohm resistor in the sky. I'm in need of data on the Eimac 3cv1500 used in the old Alpha 70v. Can anyone email me (or snail mail... I'd be glad to reimburse postage and copying costs) a data sheet? Even one of the abbreviated things now passing for data sheets would help a lot! mni tnx es 73, George T. Daughters, K6GT George T. Daughters, K6GT -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From da_kang@hotmail.com Tue Feb 20 16:25:09 2001 From: da_kang@hotmail.com (Jeff Wolf) Date: Tue, 20 Feb 2001 16:25:09 Subject: [AMPS] Runaway amp Message-ID: >>AMP: Harris RF-110A (Pair of 4CX-1500Bs) >>PROBLEM: Plate current and power output creep up after about 15 >>seconds >>under "keydown" condition. >> >>The amplifier will "run away" with itself until the overloads kick in. >> >AØ is not legal on HF. > >cheers > >- Rich..., 805.386.3734, www.vcnet.com/measures. end Chortle... It is legal, if into a dummy load while testing a amp that has a problem. Toll Free _________________________________________________________________ Get your FREE download of MSN Explorer at http://explorer.msn.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From carlseye@tampabay.rr.com Tue Feb 20 16:47:15 2001 From: carlseye@tampabay.rr.com (carl seyersdahl) Date: Tue, 20 Feb 2001 11:47:15 -0500 Subject: [AMPS] runaway amp. Message-ID: <002f01c09b5c$c81527a0$8ea22041@tampabay.rr.com> this is not exactly relevant to hi-power, but many years ago, when I was a young technician(way back there)I had a problem like that, with an audio amp stage. This was a 6AQ5 amplifier. It was doing the same thing, running away after about 15-20 seconds. all the new tubes in supply did the same thing, and as I recall no one ever found the answer, and it was looked at by many, many technicians. To this day I don't think anyone knows the whole answer. Just one of my fuzzy memories!!! carl / kz5ca -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From gm3woj@talk21.com Tue Feb 20 17:01:20 2001 From: gm3woj@talk21.com (Chris Tran GM3WOJ) Date: Tue, 20 Feb 2001 17:01:20 -0000 Subject: [AMPS] Runaway amp Message-ID: <003001c09b5e$e20ce1a0$45a6fea9@chris.tran> Hi Mike et al Interesting problem - are you measuring the grid bias and screen volts at the socket pins, or remotely (e.g. some test point) ? It could be several things, but I'd put my money on a grid bias problem - maybe a series resistor increasing in value and reducing the (-55V approx) fed to the grids. I don't think it's likely to be a fault with one of the tubes, but you can't assume anything ! 73 Chris GM3WOJ -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From dhearn@ix.netcom.com Tue Feb 20 17:21:04 2001 From: dhearn@ix.netcom.com (dan hearn) Date: Tue, 20 Feb 2001 09:21:04 -0800 Subject: [AMPS] runaway amp. References: <002f01c09b5c$c81527a0$8ea22041@tampabay.rr.com> Message-ID: <3A92A780.D1E1FF9B@ix.netcom.com> I was working on a similar problem in an old vacuum tube radio during my lunch hour many years ago. I had a signal on the grid,proper voltages on the electrodes, and no output with a good tube. I was measuring at the socket terminals. An experienced technician friend suggested that maybe the socket contact had lost its spring action and was not actually making contact with the tube pin. He proved to be right. Never overlook the possibility that a tube or connector pin has no continuity to its mating part. 73, Dan, N5AR carl seyersdahl wrote: > > this is not exactly relevant to hi-power, but many years ago, when I was a > young technician(way back there)I had a problem like that, with an audio amp > stage. This was a 6AQ5 amplifier. It was doing the same thing, running away > after about 15-20 seconds. all the new tubes in supply did the same thing, > and as I recall no one ever found the answer, and it was looked at by many, > many technicians. To this day I don't think anyone knows the whole answer. > Just one of my fuzzy memories!!! carl / kz5ca > > -- > FAQ on WWW: http://www.contesting.com/FAQ/amps > Submissions: amps@contesting.com > Administrative requests: amps-REQUEST@contesting.com > Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Kf8od@aol.com Tue Feb 20 17:37:52 2001 From: Kf8od@aol.com (Kf8od@aol.com) Date: Tue, 20 Feb 2001 12:37:52 EST Subject: [AMPS] withdraw... Message-ID: --part1_da.2921635.27c40570_boundary Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit I don't think I would have made it one more day. Quick, somebody say something about a BIG AMP! hi Mike KF8OD --part1_da.2921635.27c40570_boundary Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: 7bit I don't think I would have made it one more day. Quick, somebody say
something about a BIG AMP! hi

Mike
KF8OD --part1_da.2921635.27c40570_boundary-- -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From ac6tk@cybertime.net Tue Feb 20 17:51:12 2001 From: ac6tk@cybertime.net (J. Bradshaw) Date: Tue, 20 Feb 2001 09:51:12 -0800 Subject: [AMPS] Runaway amp References: <001c01c09b55$6987b240$0c9186d0@phil> Message-ID: <00ad01c09b65$b8511e60$330c9bcf@eat> Used to run into slight power sag routinely with Motorola Motracs. We would have to lean on them for a minute or two after alignment, then re-tweak for spec. We thought it might be from changes in interelectrode capacitance (metal plate warpage?). Could your neutralization be drifting? Cathode might be overheating? Drift in the cathode resistors? Secondary emission? Could be a real problem for RTTY. > AMP: Harris RF-110A (Pair of 4CX-1500Bs) > PROBLEM: Plate current and power output creep up after about 15 seconds > under > "keydown" condition. > > The amplifier will "run away" with itself until the overloads kick in. > > Scenario: Amp is excited to about a kw output with carrier. Key down for 30 > seconds. Power slowly increases to 1400 watts and would keep on increasing > until the overloads kick it off. When I let up on the key, the idling > current is high and then it slowly returns to its normal state. Hi Mike, Look at the individual plate currents....is each rising the same? Look at the RF at the input to the amp....is it steady all the time? Will look in the manual today and see what I can figure out. (((73))) Phil, K5PC > Have measured the grid bias, no change under "heat up conditions." Same for > the zener regulated screen voltage supply. (I had thought the zeners were > heating up and causing the screen voltage to rise, thus causing the increase > in amplification. Apparently not so, no measurable increase in screen > voltage.) > > I do not have extensive experience with ceramic tubes. Is this runaway > output because of "soft" tubes? They REALLY put out. Or maybe it is > thermal > runaway, though the powerful air system on this military amp is working ok > (and certainly makes enough noise). > > Under SSB conditions everything appears normal -- obviously due to the > markedly lower duty cycle. > > Anybody got any ideas? > > Mike > W0YR > > -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Wt8r@aol.com Tue Feb 20 18:10:22 2001 From: Wt8r@aol.com (Wt8r@aol.com) Date: Tue, 20 Feb 2001 13:10:22 EST Subject: [AMPS] Runaway amp Message-ID: <3c.7b13cc0.27c40d0e@aol.com> In a message dated 2/20/01 11:25:54 AM Eastern Standard Time, da_kang@hotmail.com writes: > > >>AMP: Harris RF-110A (Pair of 4CX-1500Bs) > >>PROBLEM: Plate current and power output creep up after about 15 >>seconds > >>under "keydown" condition. > >> > >>The amplifier will "run away" with itself until the overloads kick in. > >> > >AØ is not legal on HF. > > > >cheers > > > >- Rich..., 805.386.3734, www.vcnet.com/measures. end > > > Chortle... > > It is legal, if into a dummy load while testing a amp that has a problem. > > Toll Free >======================================================= The level of technical competence on this list is amazing..................I had never thought of that.....WOW what a revelation. Dave................... -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Ian White, G3SEK" References: <003001c09b5e$e20ce1a0$45a6fea9@chris.tran> Message-ID: <8MdAYqAuysk6EAHz@ifwtech.plus.net> Chris Tran GM3WOJ wrote: > >Hi Mike et al > >Interesting problem - are you measuring the grid bias >and screen volts at the socket pins, or remotely (e.g. >some test point) ? > Good point - and also, how accurately are you measuring the grid and screen voltages? Are you using a DVM or do the voltages only *look* kind-of constant on an analog meter? If you had not said that the screen voltage remains "constant", I would have guessed at secondary emission from the screen, causing negative screen current (out of the tube) that drives the voltage upward. That causes more output, but also more secondary emission, higher voltage, more output... until something gives. Zener stabilization is not a proof against this, especially if there is significant series resistance between the zener stack and the screen. Please let us all know how accurately you're measuring the screen and the grid voltage - right at the pins, as Chris points out, or through a *verified* low-resistance connection. 73 from Ian G3SEK Editor, 'The VHF/UHF DX Book' 'In Practice' columnist for RadCom (RSGB) http://www.ifwtech.com/g3sek -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From vk6apk@eon.net.au Tue Feb 20 21:42:51 2001 From: vk6apk@eon.net.au (Alek Petkovic) Date: Wed, 21 Feb 2001 05:42:51 +0800 Subject: Fwd: Re: [AMPS] Runaway amp Message-ID: <4.2.0.58.20010221054126.00970470@pop.eon.net.au> >Date: Tue, 20 Feb 2001 20:40:33 +0800 >To: W0YR@aol.com >From: Alek Petkovic >Subject: Re: [AMPS] Runaway amp > >Do you have a bad doorknob cap in the loading circuit perhaps? It could >cause those sort of symptoms as it heats up and changes value under load. > >73 de Alek, >VK6APK > > > >At 01:58 PM 16-02-01 -0500, you wrote: >> AMP: Harris RF-110A (Pair of 4CX-1500Bs) >> PROBLEM: Plate current and power output creep up after about 15 seconds >>under >> "keydown" condition. >> >> The amplifier will "run away" with itself until the overloads kick in. >> >> Scenario: Amp is excited to about a kw output with carrier. Key down >> for 30 >> seconds. Power slowly increases to 1400 watts and would keep on >> increasing >> until the overloads kick it off. When I let up on the key, the idling >> current is high and then it slowly returns to its normal state. >> >> Have measured the grid bias, no change under "heat up >> conditions." Same for >> the zener regulated screen voltage supply. (I had thought the zeners were >> heating up and causing the screen voltage to rise, thus causing the >> increase >> in amplification. Apparently not so, no measurable increase in screen >> voltage.) >> >> I do not have extensive experience with ceramic tubes. Is this runaway >> output because of "soft" tubes? They REALLY put out. Or maybe it is >>thermal >> runaway, though the powerful air system on this military amp is working ok >> (and certainly makes enough noise). >> >> Under SSB conditions everything appears normal -- obviously due to the >> markedly lower duty cycle. >> >> Anybody got any ideas? >> >> Mike >> W0YR >> >>Return-Path: <> >>Received: from rly-ye03.mx.aol.com (rly-ye03.mail.aol.com >>[172.18.151.200]) by air-ye04.mail.aol.com (v77_r1.21) with ESMTP; Fri, >>16 Feb 2001 12:17:33 -0500 >>Received: from paris.akorn.net (paris.akorn.net [216.1.128.10]) by >>rly-ye03.mx.aol.com (v77_r1.21) with ESMTP; Fri, 16 Feb 2001 12:17:04 -0500 >>Received: from localhost (localhost) >> by paris.akorn.net (8.11.0/8.11.0) id f1GH3lM06893; >> Fri, 16 Feb 2001 12:17:03 -0500 >>Date: Fri, 16 Feb 2001 12:17:03 -0500 >>From: Mail Delivery Subsystem >>Message-Id: <200102161717.f1GH3lM06893@paris.akorn.net> >>To: >>MIME-Version: 1.0 >>Content-Type: multipart/report; report-type=delivery-status; >> boundary="f1GH3lM06893.982343823/paris.akorn.net" >>Subject: Warning: could not send message for past 4 hours >>Auto-Submitted: auto-generated (warning-timeout) >>X-Mailer: Unknown (No Version) >> >> ********************************************** >> ** THIS IS A WARNING MESSAGE ONLY ** >> ** YOU DO NOT NEED TO RESEND YOUR MESSAGE ** >> ********************************************** >> >>The original message was received at Fri, 16 Feb 2001 08:15:51 -0500 >>from imo-r02.mx.aol.com [152.163.225.2] >> >> ----- The following addresses had transient non-fatal errors ----- >> >> >> ----- Transcript of session follows ----- >>... Deferred: Connection timed out with >>dayton.akorn.net. >>Warning: message still undelivered after 4 hours >>Will keep trying until message is 5 days old >>Reporting-MTA: dns; paris.akorn.net >>Arrival-Date: Fri, 16 Feb 2001 08:15:51 -0500 >> >>Final-Recipient: RFC822; amps@contesting.com >>Action: delayed >>Status: 4.4.1 >>Remote-MTA: DNS; dayton.akorn.net >>Last-Attempt-Date: Fri, 16 Feb 2001 12:17:02 -0500 >>Will-Retry-Until: Wed, 21 Feb 2001 08:15:51 -0500 >>Return-Path: >>Received: from imo-r02.mx.aol.com (imo-r02.mx.aol.com [152.163.225.2]) >> by paris.akorn.net (8.11.0/8.11.0) with ESMTP id f1GDFp900963 >> for ; Fri, 16 Feb 2001 08:15:51 -0500 >>Received: from W0YR@aol.com >> by imo-r02.mx.aol.com (mail_out_v29.5.) id g.6b.ff01ab2 (664) >> for ; Fri, 16 Feb 2001 08:14:27 -0500 (EST) >>From: W0YR@aol.com >>Message-ID: <6b.ff01ab2.27be81b3@aol.com> >>Date: Fri, 16 Feb 2001 08:14:27 EST >>Subject: Creepy Amplifier >>To: amps@contesting.com >>MIME-Version: 1.0 >>Content-Type: text/plain; charset="US-ASCII" >>Content-Transfer-Encoding: 7bit >>X-Mailer: AOL 5.0 for Windows sub 129 >> >>AMP: Harris RF-110A (Pair of 4CX-1500Bs) >>PROBLEM: Plate current and power output creep up after about 15 seconds >>under >>"keydown" condition. >> >>The amplifier will "run away" with itself until the overloads kick in. >> >>Scenario: Amp is excited to about a kw output with carrier. Key down for 30 >>seconds. Power slowly increases to 1400 watts and would keep on increasing >>until the overloads kick it off. When I let up on the key, the idling >>current is high and then it slowly returns to its normal state. >> >>Have measured the grid bias, no change under "heat up conditions." Same for >>the zener regulated screen voltage supply. (I had thought the zeners were >>heating up and causing the screen voltage to rise, thus causing the increase >>in amplification. Apparently not so, no measurable increase in screen >>voltage.) >> >>I do not have extensive experience with ceramic tubes. Is this runaway >>output because of "soft" tubes? They REALLY put out. Or maybe it is >>thermal >>runaway, though the powerful air system on this military amp is working ok >>(and certainly makes enough noise). >> >>Under SSB conditions everything appears normal -- obviously due to the >>markedly lower duty cycle. >> >>Anybody got any ideas? >> >>Mike >>W0YR -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From thomas.haglund@comtech-data.se Tue Feb 20 21:53:41 2001 From: thomas.haglund@comtech-data.se (Thomas haglund) Date: Tue, 20 Feb 2001 22:53:41 +0100 Subject: [AMPS] water cooling Message-ID: Hello. any one got some good internet sites with info about water-cooling tubes ? like the GS 35B and similar ? and perhaps sites with general info about water cooling tubes. //Thomas SM7TVJ -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From jtml@lanl.gov Tue Feb 20 22:39:32 2001 From: jtml@lanl.gov (John T. M. Lyles) Date: Tue, 20 Feb 2001 15:39:32 -0700 Subject: [AMPS] parameter shift in Tetrode Message-ID: Regards to the creeping Harris amplifier with 2 x 4CX1500B's: Once I was testing a 4CX1500A tetrode amplifier, class C, 1500 watts output at 100 MHz. My assistant and I left a rag or duct tape over the blower hole under the tube socket, as we were changing a tuning element and didn't want to drop any screws into the blower scroll. Being a prototype, we hadn't gotten to installing an air flow switch yet. Oops. Well, you know what happened already. We turned it on, and were perplexed as the output power dropped and the efficiency fell, for a few minutes. Then we smelled the almost burning chimney. We had thoroughly warped that tube, changed the interelectrode dimensions. It was still working when we shut it off, although the nickel plating was quite tarnished. I still have that trophy somewhere in my junk box. Uggghh. I'm not suggesting that the amplifier in question is drifting due to severe overheating, however, some sort of dimensional change or bias change is about all I could guess would do this. Clearly, something related to high duty operation as opposed to SSB is causing a drift, and that usually means something thermal. But Murphy's law can always make a fool out of me, so!!!! Good luck and let us know what you find. John K5PRO -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From chilesp@intrepid.net Wed Feb 21 00:43:53 2001 From: chilesp@intrepid.net (Pat Chiles) Date: Tue, 20 Feb 2001 19:43:53 -0500 Subject: [AMPS] 3-500Z Question Message-ID: <006601c09b9f$5e611560$87a3bed1@OTS.TREAS.GOV> This is a multi-part message in MIME format. ------=_NextPart_000_0063_01C09B75.74987000 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable I am looking for a couple of 3-500Zs. I see sellers refering to the = "old' style vs"the new style". What exactly are they referring to and = do I care as a purchaser? Anyone got at least one good one they want to = sell? Pat, K8PC ------=_NextPart_000_0063_01C09B75.74987000 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

I am looking for a couple of 3-500Zs. I see = sellers=20 refering to the "old' style vs"the new style". What exactly are = they=20 referring to and do I care as a purchaser? Anyone got at least one = good=20 one they want to sell?

Pat, K8PC

------=_NextPart_000_0063_01C09B75.74987000-- -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From philk5pc@tyler.net Wed Feb 21 00:58:24 2001 From: philk5pc@tyler.net (Phil Clements) Date: Tue, 20 Feb 2001 18:58:24 -0600 Subject: [AMPS] Runaway amp References: <4.2.0.58.20010221054126.00970470@pop.eon.net.au> Message-ID: <00d801c09ba1$66b2aec0$0c9186d0@phil> > >Do you have a bad doorknob cap in the loading circuit perhaps? It could > >cause those sort of symptoms as it heats up and changes value under load. > > > >73 de Alek, > >VK6APK > >> until the overloads kick it off. When I let up on the key, the idling > >> current is high and then it slowly returns to its normal state. How could a loading cap cause high idling current with key up? (((73))) Phil, K5PC -- FAQ on WWW: http://www.contesting.com/FAQ/amps Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com From Eric Moore" Message-ID: <002501c09c03$90f7d590$29000101@windemullerelectric.com> This is a multi-part message in MIME format. ------=_NextPart_000_0022_01C09BD9.A77539E0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Does it hurt to mix them? The SB-220 I have has one of each, but seems = to work fine. 73, Eric K8CCA ----- Original Message -----=20 From: Pat Chiles=20 To: amps@contesting.com=20 Sent: Tuesday, February 20, 2001 7:43 PM Subject: [AMPS] 3-500Z Question I am looking for a couple of 3-500Zs. I see sellers refering to the = "old' style vs"the new style". What exactly are they referring to and = do I care as a purchaser? Anyone got at least one good one they want to = sell? Pat, K8PC ------=_NextPart_000_0022_01C09BD9.A77539E0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable

Does it hurt to mix them? = The SB-220=20 I have has one of each, but seems to work fine.

73,

Eric

K8CCA

----- Original Message -----

From:=20 Pat=20 Chiles