I had six 3cx800's up for sale on swap.qth.com
One sold, some scammers, couldn't generate any interest.
Thanks for the hint on eham. I'll try that.
Robert W5AJ
PS: I buy the 3-500ZG from RFParts when need arises
On Tue, Oct 29, 2024 at 6:23 PM <dbritchie@gmail.com> wrote:
> Sell the 3cx400s for close to $250-300 each - post on eHam and they will
> evaporate quickly;
> Buy new 3-500zs for about the same on eBay.
>
> OR
>
> Sell the 3CX800s for $500-1000 the same way and
> Buy a good Alpha 78 (Actually about 4 of them) and keep the 8874s for your
> great great great grandkids to use as spares.
>
> Don't beat yourself to death redesigning 60-year old radio hardware to
> make it look like 40-year old radio hardware. If the power supply burned
> itself up, there is a reason.
> (If you still want a project, replace the Alpha plate chokes with ones
> non-resonant on 24MHz)
>
> 😊
> David W6DR
>
> -----Original Message-----
> From: Amps <amps-bounces@contesting.com> On Behalf Of
> amps-request@contesting.com
> Sent: Tuesday, October 29, 2024 2:56 PM
> To: amps@contesting.com
> Subject: Amps Digest, Vol 262, Issue 17
>
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> Today's Topics:
>
> 1. 3-500z substitutes (Paul Decker)
> 2. Re: 3-500z substitutes (Mike McCarthy, W1NR)
> 3. Re: 3-500z substitutes (Victor Rosenthal 4X6GP)
> 4. Re: 3-500z substitutes (Victor Rosenthal)
> 5. Re: 3-500z substitutes (Aleksandar Petkovic)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 29 Oct 2024 12:56:46 -0400 (EDT)
> From: Paul Decker <kg7hf@comcast.net>
> To: amps@contesting.com, amps-request@contesting.com
> Subject: [Amps] 3-500z substitutes
> Message-ID: <921267819.1276116.1730221006085@connect.xfinity.com>
> Content-Type: text/plain; charset=UTF-8
>
> Hey gang.
> I'm the proud owner of an AL-80A that's an absolute basket case. Tube is
> gone, HV section looks like it needs a rebuild.
>
> My "in stock tubes are: Qty 6 - GI-46B, Qty 6 - 3cx800A7 and U7, Qty 6 -
> 3cx400A7 and U7, Qty 2 -TH308, Qty 2 -TH328, Qty 2 - 8791, Qty 4 - 7213,
> Qty 2 - 7650, Qty 2 - 4cx1500B, (4cx350/250/150, 2c39, some other power
> tubes I don't really know) and sockets for all except the GI-46B and
> 4cx1500B.
>
> The goal is "fix'er up" with buying as little as possible. I'm leaning
> towards the GI-46B an the other triodes since there is no need for any
> extra screen bias voltages or control. The pair of 3cx400U7's (or 800's)
> would fit in real nice too, except it then requires some kind of forced air
> cooling mechanism.
>
> It looks like it's using a voltage doubler for a no load voltage of 3000V
> and loaded voltage of 2700V. I could pull a few windings off the
> transformer to lower it down a bit for the 3cx400/800 tubes, or just run at
> 2700.
>
> What do you all think would be the best fixer up route?
>
> Paul.
>
>
>
> ------------------------------
>
> Message: 2
> Date: Tue, 29 Oct 2024 13:53:39 -0400
> From: "Mike McCarthy, W1NR" <lists@w1nr.net>
> To: amps@contesting.com
> Subject: Re: [Amps] 3-500z substitutes
> Message-ID: <cfaae6a7-ba2f-4a1b-b600-e9611b05b14e@w1nr.net>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> I would start by comparing the schematic and components of the AL-800
> (factory stock 3cx800A7) just to see what parts are the same and what is
> different. I am assuming they are reasonably close. Biggest difference
> would probably be filament voltage and cathode circuit.
>
> On 10/29/2024 12:56 PM, Paul Decker via Amps wrote:
> > Hey gang.
> > I'm the proud owner of an AL-80A that's an absolute basket case. Tube is
> gone, HV section looks like it needs a rebuild.
> >
> > My "in stock tubes are: Qty 6 - GI-46B, Qty 6 - 3cx800A7 and U7, Qty 6 -
> 3cx400A7 and U7, Qty 2 -TH308, Qty 2 -TH328, Qty 2 - 8791, Qty 4 - 7213,
> Qty 2 - 7650, Qty 2 - 4cx1500B, (4cx350/250/150, 2c39, some other power
> tubes I don't really know) and sockets for all except the GI-46B and
> 4cx1500B.
> >
> > The goal is "fix'er up" with buying as little as possible. I'm leaning
> towards the GI-46B an the other triodes since there is no need for any
> extra screen bias voltages or control. The pair of 3cx400U7's (or 800's)
> would fit in real nice too, except it then requires some kind of forced air
> cooling mechanism.
> >
> > It looks like it's using a voltage doubler for a no load voltage of
> 3000V and loaded voltage of 2700V. I could pull a few windings off the
> transformer to lower it down a bit for the 3cx400/800 tubes, or just run at
> 2700.
> >
> > What do you all think would be the best fixer up route?
> >
> > Paul.
>
>
> --
> 73 de Mike, W1NR
>
> THAT was the equation. EXISTENCE!... SURVIVAL... must cancel out...
> programming!
>
> - Ruk -
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 29 Oct 2024 20:43:03 +0200
> From: Victor Rosenthal 4X6GP <k2vco.vic@gmail.com>
> To: amps@contesting.com
> Subject: Re: [Amps] 3-500z substitutes
> Message-ID: <fe7494c6-fd0f-40d1-8802-c69d815bd301@gmail.com>
> Content-Type: text/plain; charset="UTF-8"
>
>
>
> ------------------------------
>
> Message: 4
> Date: Tue, 29 Oct 2024 20:43:37 +0200
> From: Victor Rosenthal <k2vco.vic@gmail.com>
> To: amps@contesting.com
> Subject: Re: [Amps] 3-500z substitutes
> Message-ID: <25f70274-7990-400e-b7f9-85272db0e4c0@gmail.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> An AL80A has one 3-500Z and the transformer certainly can't handle a
> pair of 3cx400 or 800s. Also the bandswitch is a weak spot even for the
> stock setup, as is the tank coil. So unless all you are re-using is the
> chassis, it would be simplest to hunt around for another 3-500z. Maybe
> someone will trade one for one of the other tubes!
>
> 73,
> Victor, 4X6GP
> Rehovot, Israel
> Formerly K2VCO
> CWops no. 5
> http://www.qsl.net/k2vco
>
> On 29/10/2024 19:53, Mike McCarthy, W1NR via Amps wrote:
> > I would start by comparing the schematic and components of the AL-800
> > (factory stock 3cx800A7) just to see what parts are the same and what
> > is different. I am assuming they are reasonably close. Biggest
> > difference would probably be filament voltage and cathode circuit.
> >
> > On 10/29/2024 12:56 PM, Paul Decker via Amps wrote:
> >> Hey gang.
> >> I'm the proud owner of an AL-80A that's an absolute basket case. Tube
> >> is gone, HV section looks like it needs a rebuild.
> >>
> >> My "in stock tubes are: Qty 6 - GI-46B, Qty 6 - 3cx800A7 and U7, Qty
> >> 6 - 3cx400A7 and U7, Qty 2 -TH308, Qty 2 -TH328, Qty 2 - 8791, Qty 4
> >> - 7213, Qty 2 - 7650, Qty 2 - 4cx1500B, (4cx350/250/150, 2c39, some
> >> other power tubes I don't really know) and sockets for all except the
> >> GI-46B and 4cx1500B.
> >>
> >> The goal is "fix'er up" with buying as little as possible. I'm
> >> leaning towards the GI-46B an the other triodes since there is no
> >> need for any extra screen bias voltages or control. The pair of
> >> 3cx400U7's (or 800's) would fit in real nice too, except it then
> >> requires some kind of forced air cooling mechanism.
> >>
> >> It looks like it's using a voltage doubler for a no load voltage of
> >> 3000V and loaded voltage of 2700V. I could pull a few windings off
> >> the transformer to lower it down a bit for the 3cx400/800 tubes, or
> >> just run at 2700.
> >>
> >> What do you all think would be the best fixer up route?
> >>
> >> Paul.
> >
> >
>
>
>
> ------------------------------
>
> Message: 5
> Date: Wed, 30 Oct 2024 05:56:00 +0800
> From: Aleksandar Petkovic <vk6apk@bigpond.com>
> To: amps@contesting.com
> Subject: Re: [Amps] 3-500z substitutes
> Message-ID: <b3766870-1f51-4579-b149-8e732155915c@bigpond.com>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> Easy. Sell some of your tubes and buy a new 3-500Z.
>
> 73, Alek VK6APK
>
> PS: what would you want for a pair of 3CX800A7s?
>
>
> On 30/10/2024 12:56 am, Paul Decker via Amps wrote:
> > Hey gang.
> > I'm the proud owner of an AL-80A that's an absolute basket case. Tube is
> gone, HV section looks like it needs a rebuild.
> >
> > My "in stock tubes are: Qty 6 - GI-46B, Qty 6 - 3cx800A7 and U7, Qty 6 -
> 3cx400A7 and U7, Qty 2 -TH308, Qty 2 -TH328, Qty 2 - 8791, Qty 4 - 7213,
> Qty 2 - 7650, Qty 2 - 4cx1500B, (4cx350/250/150, 2c39, some other power
> tubes I don't really know) and sockets for all except the GI-46B and
> 4cx1500B.
> >
> > The goal is "fix'er up" with buying as little as possible. I'm leaning
> towards the GI-46B an the other triodes since there is no need for any
> extra screen bias voltages or control. The pair of 3cx400U7's (or 800's)
> would fit in real nice too, except it then requires some kind of forced air
> cooling mechanism.
> >
> > It looks like it's using a voltage doubler for a no load voltage of
> 3000V and loaded voltage of 2700V. I could pull a few windings off the
> transformer to lower it down a bit for the 3cx400/800 tubes, or just run at
> 2700.
> >
> > What do you all think would be the best fixer up route?
> >
> > Paul.
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
>
>
> ------------------------------
>
> Subject: Digest Footer
>
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>
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> ------------------------------
>
> End of Amps Digest, Vol 262, Issue 17
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>
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