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Re: [Amps] Fixing gassy tubes?

To: "Roger" <>,"Amps Amps" <>
Subject: Re: [Amps] Fixing gassy tubes?
From: "jeremy-ca" <>
Date: Thu, 26 Jul 2007 20:48:18 -0400
List-post: <>
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.


----- Original Message ----- 
From: "Roger" <>
To: "Amps Amps" <>
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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