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Date: Wed, 17 Aug 2011 12:00:13
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Subject: Amps Digest, Vol 104, Issue 19
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Today's Topics:
1. Alpha 374A add a 3d 3CX-800? (chas)
2. Re: Alpha 374A add a 3d 3CX-800? (Carl)
3. Anyone have a 160M Tank Toroid for a Alpha PA70 or PA70V?
(Mike & Becca Krzystyniak)
4. Re: Any new tube research? (Pete Lancashire)
5. Re: Anyone have a 160M Tank Toroid for a Alpha PA70 or PA70V?
(Carl)
6. Re: Alpha 374A add a 3d 3CX-800? (Roger (sub1))
----------------------------------------------------------------------
Message: 1
Date: Wed, 17 Aug 2011 02:26:22 -0500
From: chas <chasm@texas.net>
Subject: [Amps] Alpha 374A add a 3d 3CX-800?
To: Amps Amps <amps@contesting.com>
Message-ID: <4E4B6D1E.1050306@texas.net>
Content-Type: text/plain; charset=ISO-8859-1
Have purchased a 374A which is NOT at my QTH or even in this area of the
state but... it has been converted to a pair of 3CX-800s along with a mess
of other mods. Done about 3 yrs ago.
The owner cannot handle the fan noise and is going to buy an ACOM 1000
instead. I have known him for about 60 yrs and we are attached at the hip so
I feel that this is just another example of stuff we swap back and forth and
eventually, forget to whom it belongs at any time. Point to that is, he has
gone thru it with a Cobra Sr and the common MARS matrix for this state and
has tuned for best power production. It does talk but it seems to me that
the PA needs to have a txfrmr upgraded and maybe add a another bottle to it.
it did not have a vacuum relay mod done since it will be a SSB only in usage.
Not sure if this was a 3 holer to begin with or not. However, I am wondering
what it would gain me, if it could even be done - to add a 3d Cx800? The
weakest tuning freq so far is around 5.2mcy which can only crank out ca 800W.
The rest of the thing will do 1.2 to 2kw as I understand it. I am asking
the owner to write down the list of mods done by RL in Abilene and to send
that along with the amp.
isfaiK, it has a low power mod, the txfrmr is not a new Hypersil and I am
wondering if it could be upgraded to a PDahl model made for a 7n series??
I probably have not given enough info to make an informed decision or to
generate worthwhile advice but maybe I can get some questions to provide
answers to when I get the PA here.
thanks es 73
Chas k5dam
--
A: Because it messes up the order in which people normally read text. <B>
Q: Why is top-posting such a bad thing?<B>
A: Top-posting. <b>
Q: What is the most annoying thing in e-mail? <B>
.
------------------------------
Message: 2
Date: Wed, 17 Aug 2011 10:00:22 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] Alpha 374A add a 3d 3CX-800?
To: "chas" <chasm@texas.net>, "Amps Amps" <amps@contesting.com>
Message-ID: <2CB56959B596429CA1B25E3ED13AFF29@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
There is no room for three 3CX800's in there. If you want that type of power
find one of the LK-800 series.
Carl
KM1H
----- Original Message -----
From: "chas" <chasm@texas.net>
To: "Amps Amps" <amps@contesting.com>
Sent: Wednesday, August 17, 2011 3:26 AM
Subject: [Amps] Alpha 374A add a 3d 3CX-800?
>
> Have purchased a 374A which is NOT at my QTH or even in this area of the
> state but... it has been converted to a pair of 3CX-800s along with a
> mess
> of other mods. Done about 3 yrs ago.
>
> The owner cannot handle the fan noise and is going to buy an ACOM 1000
> instead. I have known him for about 60 yrs and we are attached at the hip
> so
> I feel that this is just another example of stuff we swap back and forth
> and
> eventually, forget to whom it belongs at any time. Point to that is, he
> has
> gone thru it with a Cobra Sr and the common MARS matrix for this state and
> has tuned for best power production. It does talk but it seems to me that
> the PA needs to have a txfrmr upgraded and maybe add a another bottle to
> it.
> it did not have a vacuum relay mod done since it will be a SSB only in
> usage.
>
> Not sure if this was a 3 holer to begin with or not. However, I am
> wondering
> what it would gain me, if it could even be done - to add a 3d Cx800? The
> weakest tuning freq so far is around 5.2mcy which can only crank out ca
> 800W.
> The rest of the thing will do 1.2 to 2kw as I understand it. I am asking
> the owner to write down the list of mods done by RL in Abilene and to send
> that along with the amp.
>
> isfaiK, it has a low power mod, the txfrmr is not a new Hypersil and I am
> wondering if it could be upgraded to a PDahl model made for a 7n series??
>
> I probably have not given enough info to make an informed decision or to
> generate worthwhile advice but maybe I can get some questions to provide
> answers to when I get the PA here.
>
> thanks es 73
>
> Chas k5dam
>
>
>
> --
> A: Because it messes up the order in which people normally read text. <B>
> Q: Why is top-posting such a bad thing?<B>
> A: Top-posting. <b>
> Q: What is the most annoying thing in e-mail? <B>
>
> .
> _______________________________________________
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> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
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------------------------------
Message: 3
Date: Wed, 17 Aug 2011 09:55:37 -0500
From: "Mike & Becca Krzystyniak" <k9mk@flash.net>
Subject: [Amps] Anyone have a 160M Tank Toroid for a Alpha PA70 or
PA70V?
To: "'Amps Amps'" <amps@contesting.com>
Message-ID: <004501cc5ced$b9ca01d0$2d5e0570$@net>
Content-Type: text/plain; charset="us-ascii"
Already talked with the folks at Alpha with little help, so I'm trying
here.
Does anyone have a 160M tank coil (the wound toroid) from an old Alpha
PA70 or PA70V they want to sell?
Also, would anyone know if the 160M tank toroid for the PA70 series and
the 77 series amps might be the same?
Thanks in advance.
73's Mike
------------------------------
Message: 4
Date: Wed, 17 Aug 2011 08:33:20 -0700
From: Pete Lancashire <pete@petelancashire.com>
Subject: Re: [Amps] Any new tube research?
To: amps@contesting.com
Message-ID:
<CAA-F0u_c5WRBJwvJvuHzeQ+0k+Yetytv9gF=EL4emGggiZ94Gw@mail.gmail.com>
Content-Type: text/plain; charset=UTF-8
some what of a Segway, is tubes for AC->DC->AC transmission. That segment had
converted to SS quite some time ago.
-pete
On Tue, Aug 16, 2011 at 11:01 AM, John Lyles <jtml@losalamos.com> wrote:
> Ignoring more exotic tubes like gyrocons, gyrotrons, TWTs, relativistic
> electron devices, things that the Naval Research Lab is doing, there is
> still vacuum tube improvement being done in the industry. Notice that I
> didn't say research. As broadcasting and wireless has pretty much
> embraced silicon devices (except for HF transmission at high power),
> advances in power tubes are being made to support more demanding
> applications such as scientific and military needs. Not amateur radio
> and not AM/FM radio. Ham radio saw the peak of development 20-30 years
> ago, although occasional variants of old tubes are introduced for
> specific targets, like the somewhat successful 3CX1200 introductions
> from Eimac that were supposed to replace glass 3-500Z sockets as well as
> 8877s. There are others too, that hams embrace here. Television has
> converted to solid state where it is feasible, although IOTs (a linear
> beam tube with a grid) have held ground in UHF for higher power due to
> simplicity and lower cost.
>
> IOTs, klystrons (multi gun/beam) and gridded tetrodes are still being
> designed for various projects, such as resistive heating sources for
> fusion machines and as sources for RF particle accelerators. There are
> many accelerators built and planned to be built worldwide, serving
> industrial to basic science applications. Not just big bang machines
> like LHC at CERN.
>
> Techniques like multiphase cooling (Hypervapotron is one mfr's name) to
> exchange anode heat with water at much higher efficiency, pyrolytic
> graphite for grids, and improvements to cathodes for higher loading are
> all improvements that are working their way into big tubes. These make
> tremendous increases in power density. In cathode loading, a tube with
> thoriated tungsten (going back to Langmuir and others at GE) can deliver
> as much as 3 Amps per cm^2 of electrons in a well designed tube to get
> lifetimes > 20,000 hours. Figure the size of the filament basket and you
> understand how the peak current can be 1000 amps overall. Thats just not
> possible in a transistor junction, no matter what type. Combining lots
> of transistors gets there, however, at a cost.
>
> For example, the TH628 from Thales has over 1 MW plate dissipation, with
> less water flow and high performance into the VHF. The 4CM2500KG from
> Eimac has over 2 MW plate dissipation, with slightly lower frequency
> ranges but very high CW power. I wouldn't say that the few remaining
> tube manufacturers are sitting still, but they are not cranking out new
> designs yearly either. They are making measured step improvements to
> their existing products, a lot easier than starting over with a clean
> page. These two examples are sort of the crowns for these two companies
> to push performance limits.
>
> Others mentioned cold cathode research with field emission and such.
> Metal filament and oxide-type tubes and cathodes provide excellent long
> life performance, if properly rated for the application. It's when
> engineers try to exceed the ratings that lifetimes shorten. Or
> manufacturers reduce quality (rising gas levels for example). Similar
> lifetime-reductions happen in solid state devices when application
> demands more than the device designer expected, except much quicker -
> flash, pop.
>
> As a designer of power amplifiers using both tubes and transistors, I
> see a good trend in solid state, with 1200 watts or more per device. But
> I don't expect to see a megawatt in a device, something that I can and
> do see with new tubes. Ham radio will eventually quit using tubes except
> for nostalgia reasons; we are still seeing a few 304TL and 450TH
> amplifiers getting built due to having the parts and for fun. As long as
> their is a market, the Far East will provide bottles for building simple
> amplifiers. Don't expect any new tubes for this, however. HV power is
> getting harder to come by due to cost of iron and copper. Switch mode
> technology comes just in time.
> 73
> John
> K5PRO
>
> N7CXI wrote:
> ?> This discussion of "super semis" makes me wonder if anyone is still
> ?> engaged in vacuum tube research these days. Could any of the basic
> ?> tube wear points be improved on with modern technology? Could
> ?> filaments be made to emit twice as long without degradation?
>
> ?> I just looked at the CPI Eimac site and I can't see where they're
> ?> motivated or have the resources to innovate at the basic level. They
> ?> list "Amateur Service" as a product category, which can't bode well
> ?> for volume sales... Assuming MOSFET technology passes tubes by at
> ?> high power levels, will they just go quietly into the night?
>
> _______________________________________________
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> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
------------------------------
Message: 5
Date: Wed, 17 Aug 2011 12:41:13 -0400
From: "Carl" <km1h@jeremy.mv.com>
Subject: Re: [Amps] Anyone have a 160M Tank Toroid for a Alpha PA70 or
PA70V?
To: "Mike & Becca Krzystyniak" <k9mk@flash.net>, "'Amps Amps'"
<amps@contesting.com>
Message-ID: <9D7EECDB99A84AB1941CEA428658B293@computer1>
Content-Type: text/plain; format=flowed; charset="iso-8859-1";
reply-type=original
I would think the toroids and the coil is the same since the 3 tubes are
similar and on 160 nothing is that critical. The toroid itself is likely a
Micrometals #2 mix. Go to Amidon and get one of the same size, use Scotch 27
tape and Teflon wire.
Carl
KM1H
----- Original Message -----
From: "Mike & Becca Krzystyniak" <k9mk@flash.net>
To: "'Amps Amps'" <amps@contesting.com>
Sent: Wednesday, August 17, 2011 10:55 AM
Subject: [Amps] Anyone have a 160M Tank Toroid for a Alpha PA70 or PA70V?
> Already talked with the folks at Alpha with little help, so I'm trying
> here.
>
> Does anyone have a 160M tank coil (the wound toroid) from an old Alpha
> PA70 or PA70V they want to sell?
>
> Also, would anyone know if the 160M tank toroid for the PA70 series and
> the 77 series amps might be the same?
>
> Thanks in advance.
>
> 73's Mike
>
>
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>
>
> -----
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> Checked by AVG - www.avg.com
> Version: 10.0.1392 / Virus Database: 1520/3840 - Release Date: 08/17/11
>
------------------------------
Message: 6
Date: Wed, 17 Aug 2011 14:32:03 -0400
From: "Roger (sub1)" <sub1@rogerhalstead.com>
Subject: Re: [Amps] Alpha 374A add a 3d 3CX-800?
To: amps@contesting.com
Message-ID: <4E4C0923.8000405@rogerhalstead.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
On 8/17/2011 3:26 AM, chas wrote:
> Have purchased a 374A which is NOT at my QTH or even in this area of the
> state but... it has been converted to a pair of 3CX-800s along with a mess
> of other mods. Done about 3 yrs ago.
>
> The owner cannot handle the fan noise and is going to buy an ACOM 1000
> instead. I have known him for about 60 yrs and we are attached at the hip so
> I feel that this is just another example of stuff we swap back and forth and
> eventually, forget to whom it belongs at any time. Point to that is, he has
> gone thru it with a Cobra Sr and the common MARS matrix for this state and
> has tuned for best power production. It does talk but it seems to me that
> the PA needs to have a txfrmr upgraded and maybe add a another bottle to it.
> it did not have a vacuum relay mod done since it will be a SSB only in
> usage.
>
> Not sure if this was a 3 holer to begin with or not. However, I am wondering
> what it would gain me, if it could even be done - to add a 3d Cx800?
The early Alpha series amps such as the 76 and 374 series are very
compact amps with little room to spare. They will take, or I should say
that some will take 3 8874's (3CX400A7s) which is a total of 1200 watts
plate dissipation. A pair of 3CX800A7's has 1600 watts dissipation, but
a pair of them are easily as large or larger than 3 of the 8874's.
Transformer size is also limited due to space.
The pair of 3CX800A7's and 3CPX800A7s are popular conversions even
though the KVA rating of the transformer may be a bit anemic they'll
put out plenty of PEP power. Plate transformers are available with the
proper filament winding and higher voltage for the 3CPX800A7's for a
neat conversion. I think Carl has a good deal of experience with the
Alpha conversions.
But back to 3 3CX800A7s. There is no space in there for 3 of them and
the transformer doesn't have enough of a KVA rating to take advantage of
them if you could get them to fit.
73
Roger (K8RI)
> The
> weakest tuning freq so far is around 5.2mcy which can only crank out ca 800W.
> The rest of the thing will do 1.2 to 2kw as I understand it. I am asking
> the owner to write down the list of mods done by RL in Abilene and to send
> that along with the amp.
>
> isfaiK, it has a low power mod, the txfrmr is not a new Hypersil and I am
> wondering if it could be upgraded to a PDahl model made for a 7n series??
>
> I probably have not given enough info to make an informed decision or to
> generate worthwhile advice but maybe I can get some questions to provide
> answers to when I get the PA here.
>
> thanks es 73
>
> Chas k5dam
>
>
>
------------------------------
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