So youre swapping out the 6146's for the Penta? Age is catching up Roger,
its the HT-33. Great old amps. I might even have a socket.
Carl
KM1H
----- Original Message -----
From: "Roger" <sub1@rogerhalstead.com>
To: "Amps Amps" <amps@contesting.com>
Sent: Thursday, July 26, 2007 8:26 PM
Subject: [Amps] Fixing gassy tubes?
> One of the worst tubes I've run into for being gassy are the old
> PL-172/8295A.
> These were, to me, a great tube. They are an external anode metal tube
> with
> a very coarse set of fins in the radiator so they do not require much in
> the way of back pressure. Just a plain old fan blowing air up around the
> the
> tube and through the fins makes for suficient cooling. Unfortunately
> instead of ceramic the tubes use a glass to metal seal and although there
> seem to be quite a few floating around, many are gassy. The only ham amp
> that used them was the Hallicrafters HT-32A and B series AFAIK.
>
> Other than just letting them cook with out the high voltage on, it there
> any
> thing that can be done for these outside of turning them into expensive
> conversation pieces?
>
> BTW the straight 8295A was ceramic/metal and they do not seem to show up
> gassy, or at least I've not seen any. OTOH a NOS 8295A is worth a small
> fortune if you are the one doing the purchasing.
>
> Yes, I do have an HT-32B I'm just finishing up on the restoration. The
> PL-172 in it is good.
>
> 73
>
> Roger (K8RI)
>
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