From ve3zi at yahoo.com Wed Feb 1 16:21:47 2023 From: ve3zi at yahoo.com (Roger Parsons) Date: Wed, 1 Feb 2023 21:21:47 +0000 (UTC) Subject: [Amps] PT-3000 References: <942269992.2210030.1675286507206.ref@mail.yahoo.com> Message-ID: <942269992.2210030.1675286507206@mail.yahoo.com> A little while ago I wrote about some experiences with a PT-3000 that I have been working on. This work was completely interupted by an unpleasant and debilitating bout of Covid. Anyway, I am feeling somewhat better now and thought others may be marginally interested in my endeavours. To recap, the amp originally had the blower wired between one hot wire and ground, there being no separate neutral connection. The tube filament was powered from a switch mode supply connected across the 240V supply. I decided to use a transformer for the filament and to connect both blower and transformer between opposite 120V hot wires and the main transformer CT. Of course, nothing is ever as simple as it appears. When the main switch is operated, power is connected to the HT transformer (via 100W of soft-start resistors) as well as two series connected 120-12V transformers to provide the 24V relay supply. There is a time delay before PTT can be applied of 180 seconds. Unfortunately, this time delay applies to everything except the 24V supply, so the filament does not get full voltage until PTT is applied, and gets reduced voltage in every receive period. This is obviously rather undesirable, and FWIW is not a design 'feature' that I have ever seen before. The cure was pretty easy - to introduce an additional much shorter time delay for the main transformer - whilst retaining the long delay for PTT, etc. Perhaps a dollar's worth of components. I also have a variable resistor in series with the primary of the filament transformer which allows me to set the filament to exactly 5V, and to reduce the switch on surge current. Finally, one other pretty unique feature about this prototype rig - there is a TO220 7824 voltage regulator on the relay supply. No fewer than 8 connections were made to the output lead, all hanging in mid air.... 73 Roger VE3ZI From barberaudio at gmail.com Fri Feb 3 17:17:48 2023 From: barberaudio at gmail.com (Jim Barber) Date: Fri, 3 Feb 2023 14:17:48 -0800 Subject: [Amps] Cleaning/lubing vacuum caps? Message-ID: I have an old glass Jennings vacuum cap that pulls harder than I think it should. I've cleaned and lubed the puller screw, as well as the plates and bearing in the end of the "puller housing". It helped some, but the cap still pulls a little hard. Has anyone removed the "puller housing", put the cap in a jig, pulled it and cleaned/lubed the sleeve? That's the only other thing I can think of to do, but I'm a little nervous about doing it. Thanks, Jim N7CXI From barberaudio at gmail.com Tue Feb 7 12:29:16 2023 From: barberaudio at gmail.com (Jim Barber) Date: Tue, 7 Feb 2023 09:29:16 -0800 Subject: [Amps] 8877 - HV with heater, or later? Message-ID: Back on the original topic, I found what appears to be an updated 3CX1500A7/8877 data sheet on the CPII site. Updated, that is since the last time I looked there... (!) https://www.cpii.com/docs/datasheets/213/3CX1500A7-8877.pdf *My original question was answered on page 4:* "CATHODE WARM-UP/COOL-DOWN TIME - It is recommended that heater voltage be applied for a minimum of three minutes* before anode voltage* and drive voltage are applied, to allow for proper conditioning of the cathode surface. It is also recommended that after all voltages are removed from the tube that air cooling be allowed to run for several minutes to allow for proper cooldown." *Other interesting tidbits:* "HEATER OPERATION ? The heater power supply should be isolated from ground (ie.; no center tap on the secondary of a transformer if used)." *I happened to set my current amp up that way because the heater xformer didn't have a center tap, not because I thought it was bad practice. I also tied the cathode and heater elements together at the socket with 0.01uF caps to prevent RF "overdrive" of the heater. Right or wrong it seems to work fine. That trick is described in a project from Bill Orr's handbook. Point being, lots of 8877's out there with no heater choke and one side of the heater tied to ground.* "INPUT CIRCUIT - When the 3CX1500A7/8877 is operated as a cathode driven rf amplifier, the use of a resonant circuit in the cathode is recommended. For best results with a single ended amplifier, it is suggested that the cathode tank circuit operate with a ?Q? of 5 or more." *Hmmmm why? 4 has worked the best for me. What sin am I committing? Potential stabliity? Some difference in IMD?* Anyway - sometimes answers do appear, even if some of them raise more questions. :-) 73, Jim N7CXI From wa9wsj at yahoo.com Mon Feb 20 19:02:45 2023 From: wa9wsj at yahoo.com (Tom WA9WSJ) Date: Tue, 21 Feb 2023 00:02:45 +0000 (UTC) Subject: [Amps] Need a replacement choke References: <521043419.770570.1676937765087.ref@mail.yahoo.com> Message-ID: <521043419.770570.1676937765087@mail.yahoo.com> Hello Gents, By any distant chance, does anyone have a plate choke for an NCL-2000 amp that you might sell?National Pn. B51448. 165 uH 800 ma DC, (so says the manuals parts list). Mine has not failed, yet. Looks like it got hot and turned color, black. Like to have a spare if it gives up the ghost! While I'm thinking of it, any spare parts would be great to get also, especially the tubes. 8122. Thanks! 73 Tom wa9wsj From gudguyham at aol.com Mon Feb 20 19:09:45 2023 From: gudguyham at aol.com (gudguyham at aol.com) Date: Tue, 21 Feb 2023 00:09:45 +0000 (UTC) Subject: [Amps] Need a replacement choke In-Reply-To: <521043419.770570.1676937765087@mail.yahoo.com> References: <521043419.770570.1676937765087.ref@mail.yahoo.com> <521043419.770570.1676937765087@mail.yahoo.com> Message-ID: <2093049967.2405229.1676938185499@mail.yahoo.com> I have a ncl2000 ?parts or repair or just use it. ?Has tubes. ?Never tried it. $300 takes it. Sent from the all new AOL app for iOS On Monday, February 20, 2023, 7:02 PM, Tom WA9WSJ via Amps wrote: Hello Gents, By any distant chance, does anyone have a plate choke for an NCL-2000 amp that you might sell?National Pn. B51448. 165 uH 800 ma DC, (so says the manuals parts list). Mine has not failed, yet. Looks like it got hot and turned color, black. Like to have a spare if it gives up the ghost! While I'm thinking of it, any spare parts would be great to get also, especially the tubes. 8122. Thanks! 73 Tom wa9wsj _______________________________________________ Amps mailing list Amps at contesting.com http://lists.contesting.com/mailman/listinfo/amps From jim.thom at telus.net Tue Feb 21 15:53:20 2023 From: jim.thom at telus.net (jim.thom jim.thom@telus.net) Date: Tue, 21 Feb 2023 12:53:20 -0800 Subject: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 16 Message-ID: Here, finally the 17.6 kva CCS / 280 lb custom Heyboer plate xfmr is unpacked. B+ supply is being built this week. I specd' the pri + sec taps, temp rise over ambient, max secondary DC resistance etc, for Scott. Scott just moved into a bigger home...on 2 acres, on Feb 10th, so he was tied up with the huge moving endeavor, removing old tower, and packing hundreds of lbs of radio gear to the new workshop. . https://www.youtube.com/watch?v=og9hwdIaIXk From jim.thom at telus.net Wed Feb 22 16:34:54 2023 From: jim.thom at telus.net (jim.thom jim.thom@telus.net) Date: Wed, 22 Feb 2023 13:34:54 -0800 Subject: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 17 Message-ID: Here, the bottom of the cabinet is re-enforced with 1.5" of plywood. Casters added. Notches cut out etc. https://www.youtube.com/watch?v=1HiuMP3iieQ Plate xfmr installed. From jtml at losalamos.com Thu Feb 23 00:18:28 2023 From: jtml at losalamos.com (John Lyles) Date: Wed, 22 Feb 2023 22:18:28 -0700 Subject: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 16 In-Reply-To: References: Message-ID: <79598e32-d1de-1a10-f256-1eae63a43ee4@losalamos.com> Jim, you could subtract your meter lead resistance from each winding measurement, its even better. Also, notice that the value of R slowly dropped. This is because the secondary is resisting the step change flow of current, just like a capacitor resists a change in voltage. Be careful about having hand on each probe as there might be kick, the EMF from disconnecting that continuous current. It used to be much worse when using a Simpson 260 VOM. Don't ask me how I would know that. That is an awfully heavy iron part to place on a sheet metal chassis bottom. It might help to add some flat stock across from end to end, like 2 inch wide aluminum bars. This spreads the load and prevents dimpling of the sheet metal. In commercial transmitters with even smaller transformers, we used 3/8 steel plate for the bottom and drilled holes, welded nuts on the bottom for bolting the iron in. This also had some I beams welded to it, so that a pallet jack or fork lift could move it. That would be overkill for yours. 73 John K5PRO > Message: 1 > Date: Tue, 21 Feb 2023 12:53:20 -0800 > From: "jim.thom jim.thom at telus.net" > To: amps at contesting.com > Subject: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 16 > > Here, finally the 17.6 kva CCS / 280 lb custom Heyboer plate xfmr is > unpacked. > B+ supply is being built this week. I specd' the pri + sec taps, temp rise > over ambient, max secondary DC resistance etc, for Scott. Scott just moved > into a bigger home...on 2 acres, on Feb 10th, so he was tied up with the > huge moving endeavor, removing old tower, and packing hundreds of lbs of > radio gear to the new workshop. . > > https://www.youtube.com/watch?v=og9hwdIaIXk From jim.thom at telus.net Thu Feb 23 16:17:33 2023 From: jim.thom at telus.net (jim.thom jim.thom@telus.net) Date: Thu, 23 Feb 2023 13:17:33 -0800 Subject: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 16 Message-ID: Date: Wed, 22 Feb 2023 22:18:28 -0700 From: John Lyles To: amps at contesting.com Subject: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 16 Greetings to all, ? ? ? ? ?I have just been advised that Alpha Max upgrade kits are once again available.? If interested, contact George, K4GVT A at george at k4gvt for details. 73 de Lon, K5JV 281-795-1335 From kenk4zw at gmail.com Fri Feb 24 11:04:52 2023 From: kenk4zw at gmail.com (Ken Claerbout) Date: Fri, 24 Feb 2023 11:04:52 -0500 Subject: [Amps] Alpha Max upgrade In-Reply-To: References: Message-ID: Thanks Lon. On a somewhat related subject, I need to replace a blower that is starting to fail. I have the motor but need the fan. I understand Alpha has fans but they are not taking orders either online or via the phone. Anyone have one that is excess to their needs? 73 Ken K4ZW On Fri, Feb 24, 2023 at 10:51 AM K5jv wrote: > > Greetings to all, > > I have just been advised that Alpha Max upgrade kits are once again available. If interested, contact George, K4GVT A at george at k4gvt for details. > > 73 de Lon, K5JV > 281-795-1335 > _______________________________________________ > Amps mailing list > Amps at contesting.com > http://lists.contesting.com/mailman/listinfo/amps From tom.hellem at gmail.com Fri Feb 24 11:07:39 2023 From: tom.hellem at gmail.com (Tom Hellem) Date: Fri, 24 Feb 2023 09:07:39 -0700 Subject: [Amps] Alpha Max upgrade In-Reply-To: References: Message-ID: Lon- Can we assume George's email address ends in .com? Tom K0SN On Fri, Feb 24, 2023 at 8:51 AM K5jv wrote: > Greetings to all, > > I have just been advised that Alpha Max upgrade kits are once > again available. If interested, contact George, K4GVT A at george at k4gvt > for details. > > 73 de Lon, K5JV > 281-795-1335 > _______________________________________________ > Amps mailing list > Amps at contesting.com > http://lists.contesting.com/mailman/listinfo/amps > From dougzzz at gmail.com Sat Feb 25 11:11:10 2023 From: dougzzz at gmail.com (Douglas Zwiebel) Date: Sat, 25 Feb 2023 11:11:10 -0500 Subject: [Amps] TenTec Centurion "broken" Message-ID: Last night, the amp was working great (as usual). This morning, when I turned it on (power switch), the Transmit light was on (RED) and the fan was not running. I pulled the PTT line, but no change. Position of the other front panel switches does not matter (operate/standby and QSK/PTT). Any suggestions? thanks de Doug KR2Q From gudguyham at aol.com Sat Feb 25 11:52:49 2023 From: gudguyham at aol.com (gudguyham at aol.com) Date: Sat, 25 Feb 2023 16:52:49 +0000 (UTC) Subject: [Amps] TenTec Centurion "broken" In-Reply-To: References: Message-ID: <523756706.492078.1677343969832@mail.yahoo.com> The key line shorted to ground or perhaps a shorted transistor on the QSK board. Sent from the all new AOL app for iOS On Saturday, February 25, 2023, 11:11 AM, Douglas Zwiebel wrote: Last night, the amp was working great (as usual). This morning, when I turned it on (power switch), the Transmit light was on (RED) and the fan was not running.? I pulled the PTT line, but no change. Position of the other front panel switches does not matter (operate/standby and QSK/PTT). Any suggestions? thanks de Doug KR2Q _______________________________________________ Amps mailing list Amps at contesting.com http://lists.contesting.com/mailman/listinfo/amps From jim.thom at telus.net Sat Feb 25 12:36:15 2023 From: jim.thom at telus.net (jim.thom jim.thom@telus.net) Date: Sat, 25 Feb 2023 09:36:15 -0800 Subject: [Amps] 10 KW CCS ON 6M...USING THE 3CX-6000A7... PART 18 Message-ID: Here, the pair of 60 uf (at 5 kv) oil caps are mounted. Caps will be wired in series, and 4 x 100k bleeders used. Center junction of resistors is wired to center junction of the series caps. Each oil cap is isolated from each other..and chassis. This ensures each oil cap has the same V drop across it. 6.5 kv unload B+, so 3250 v across each of the 5 kv rated caps. 3 x contactors used in total, with contacts in parallel. The 'small' 0-270 vac @ 5 amp variac will be used to control the fil V. 2 x 7.5 vac @ 50 amp fil xfmrs are wired in parallel..to handle the tubes 7.0 vac @ 79 amp CCS requirement. The variac will get it's own right angle drive, so the fil V adjustment can be done on the rear apron. The big EBM-Papst blower will hang off the top lid of the B+ supply..and will provide 330 cfm @ .9" pressure for the tube.(tube requires 204 cfm @ just .4" pressure, but by using the bigger blower, the CCS anode diss is increased by 20% to 7.2 kw. This is with a 40 deg C (104 F) ambient intake air temp. With a more normal 20-25 C (68-75 F) intake air temp, CCS anode diss is further increased to 8 kw CCS. It's an easy tube to cool, due to it's small ceramic..'stem' (identical to a 3CX-3000A7)...and large diameter anode fins, esp on the underside of the fins. 2 x holes with mating finger guards on side of B+ supply, allow for the air intake to the blower. The 330 cfm room air will also cool all the components, like plate and fil xfmr's, bleeders etc. A custom gasket will be used between top lid of B+ supply...and bottom lid of the smaller RF deck box, that will sit on top of the B+ supply. That's how the compressed air gets to the cathode plenum..then up through the anode fins..and exhausted out the custom, screened portion of the top lid of RF deck. It will all come together in the next 1-3 days. Scott has a bunch of SB-220's and Various Ameritron amps to fix, so has severe time constraints as is. https://www.youtube.com/watch?v=98e93-CIN7c From george at k4gvt.com Sat Feb 25 17:58:59 2023 From: george at k4gvt.com (George Tarnovsky) Date: Sat, 25 Feb 2023 22:58:59 +0000 Subject: [Amps] Alpha Max upgrade In-Reply-To: References: Message-ID: Folks, these kits are no longer available. Sorry for any inconvenience. 73, George, K4GVT -----Original Message----- From: Amps On Behalf Of K5jv Sent: Friday, February 24, 2023 10:43 AM To: gudguyham--- via Amps ; K5jv Subject: [Amps] Alpha Max upgrade Greetings to all, ? ? ? ? ?I have just been advised that Alpha Max upgrade kits are once again available.? If interested, contact George, K4GVT A at george at k4gvt for details. 73 de Lon, K5JV 281-795-1335 _______________________________________________ Amps mailing list Amps at contesting.com http://lists.contesting.com/mailman/listinfo/amps From maflynn at theflynn.org Sun Feb 26 08:46:41 2023 From: maflynn at theflynn.org (Martin Flynn) Date: Sun, 26 Feb 2023 08:46:41 -0500 Subject: [Amps] 3CX-6000A7 Socket Message-ID: <8cb8bd94-d520-6fd3-fea0-fb442a3de593@theflynn.org> Any know where to source a socket for a 3CX-6000A7? Datasheet at https://www.cpii.com/docs/datasheets/76/3CX6000A7%20-%20YU-148.pdf does not specify? a pert number, and RF Parts can no longer source them Would prefer not to use collets 73 Martin Flynn W2RWJ From jim.thom at telus.net Mon Feb 27 22:49:17 2023 From: jim.thom at telus.net (jim.thom jim.thom@telus.net) Date: Mon, 27 Feb 2023 19:49:17 -0800 Subject: [Amps] (no subject) Message-ID: Date: Sun, 26 Feb 2023 08:46:41 -0500 From: Martin Flynn To: amps at contesting.com Subject: [Amps] 3CX-6000A7 Socket I think I have read about this in the past, but not sure. I was using the amp on 10m working some DX. Went to shut it off with the power switch, but the amp stayed powered up. I ended up unplugging it. In reviewing the schematic it seemed like the only issue could be the power switch arced and welded shut. I don't have the schematic in front of me now. Well, I was going to confirm all of this before looking for a replacement switch, or relay if that is the issue. The amp now powers up and shuts off ok. What? Something welded and then broke loose? Doug N4IJ From k2vco.vic at gmail.com Tue Feb 28 14:17:27 2023 From: k2vco.vic at gmail.com (Victor Rosenthal 4X6GP) Date: Tue, 28 Feb 2023 21:17:27 +0200 Subject: [Amps] Kenwood TL-922 Power off issue In-Reply-To: References: Message-ID: From gudguyham at aol.com Tue Feb 28 15:02:33 2023 From: gudguyham at aol.com (gudguyham at aol.com) Date: Tue, 28 Feb 2023 20:02:33 +0000 (UTC) Subject: [Amps] Kenwood TL-922 Power off issue In-Reply-To: References: Message-ID: <248743503.1299472.1677614553476@mail.yahoo.com> The amp runs a few minutes after you turn it off but fan only. ?That?s normal, but fan only. Sent from the all new AOL app for iOS On Tuesday, February 28, 2023, 12:43 PM, N4IJ wrote: I think I have read about this in the past, but not sure. I was using the amp on 10m working some DX. Went to shut it off with the power switch, but the amp stayed powered up. I ended up unplugging it. In reviewing the schematic it seemed like the only issue could be the power switch arced and welded shut.? I don't have the schematic in front of me now.? Well, I was going to confirm all of this before looking for a replacement switch, or relay if that is the issue.? The amp now powers up and shuts off ok. What?? Something welded and then broke loose? Doug N4IJ _______________________________________________ Amps mailing list Amps at contesting.com http://lists.contesting.com/mailman/listinfo/amps From gudguyham at aol.com Tue Feb 28 15:02:33 2023 From: gudguyham at aol.com (gudguyham at aol.com) Date: Tue, 28 Feb 2023 20:02:33 +0000 (UTC) Subject: [Amps] Kenwood TL-922 Power off issue In-Reply-To: References: Message-ID: <248743503.1299472.1677614553476@mail.yahoo.com> The amp runs a few minutes after you turn it off but fan only. ?That?s normal, but fan only. Sent from the all new AOL app for iOS On Tuesday, February 28, 2023, 12:43 PM, N4IJ wrote: I think I have read about this in the past, but not sure. I was using the amp on 10m working some DX. Went to shut it off with the power switch, but the amp stayed powered up. I ended up unplugging it. In reviewing the schematic it seemed like the only issue could be the power switch arced and welded shut.? I don't have the schematic in front of me now.? Well, I was going to confirm all of this before looking for a replacement switch, or relay if that is the issue.? The amp now powers up and shuts off ok. What?? Something welded and then broke loose? Doug N4IJ _______________________________________________ Amps mailing list Amps at contesting.com http://lists.contesting.com/mailman/listinfo/amps From dougn4ij at gmail.com Tue Feb 28 15:06:30 2023 From: dougn4ij at gmail.com (N4IJ) Date: Tue, 28 Feb 2023 15:06:30 -0500 Subject: [Amps] Kenwood TL-922 Power off issue In-Reply-To: <248743503.1299472.1677614553476@mail.yahoo.com> References: <248743503.1299472.1677614553476@mail.yahoo.com> Message-ID: I knew I should have mentioned that I knew about the fan. The fan has a separate AC input and a separate relay for that. The amp would not shut down. Not just the fan. Doug N4IJ On Tue, Feb 28, 2023 at 3:02?PM gudguyham at aol.com wrote: > The amp runs a few minutes after you turn it off but fan only. That?s > normal, but fan only. > > > Sent from the all new AOL app for iOS > > > On Tuesday, February 28, 2023, 12:43 PM, N4IJ wrote: > > I think I have read about this in the past, but not sure. I was using > the amp on 10m working some DX. Went to shut it off with the power > switch, but the amp stayed powered up. I ended up unplugging it. > In reviewing the schematic it seemed like the only issue could be the > power switch arced and welded shut. I don't have the schematic in front > of me now. Well, I was going to confirm all of this before looking for a > replacement switch, or relay if that is the issue. The amp now powers up > and shuts off ok. > What? Something welded and then broke loose? > > Doug N4IJ > _______________________________________________ > Amps mailing list > Amps at contesting.com > http://lists.contesting.com/mailman/listinfo/amps > >