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Re: [Amps] Alpha 78 with 8874 Triodes

To: "Chuck Curran" <ccurran@wi.rr.com>, <amps@contesting.com>
Subject: Re: [Amps] Alpha 78 with 8874 Triodes
From: "Carl" <km1h@jeremy.mv.com>
Date: Wed, 23 Apr 2014 16:55:24 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
I have a 3 tube 76PA and when those give up there is plenty room for a pair of 3CX800A7's or the 3CPX version, only $400 ea from Alpha and good pulls about half that. Add a filament transformer and new red silicone rubber cimneys.
Lots of info via Google.

Meanwhile the 8874's will still do 1800W on a quick test with well under rated grid current; I run them at 1200W.

Carl
KM1H

----- Original Message ----- From: "Chuck Curran" <ccurran@wi.rr.com>
To: <amps@contesting.com>
Sent: Wednesday, April 23, 2014 3:48 PM
Subject: [Amps] Alpha 78 with 8874 Triodes


Hello the Group:



I am working on an Alpha 78 with three 8874 triodes, that are still in good
shape.  This particular amp was one that was built in late 1980, and the
interior is in like new condition.  However, it was one of those that was
built with the "SCRATCH PROOF" paint. The catch is the paint broke down on all of the Alpha amps that used it and is sticky like a coating of honey was
applied to all surfaces.



I was able to obtain a brand new front panel and I stripped and repainted
the sheet metal cover.  The cover turned out beautiful, just like the new
front panel is, using a color coordinated paint my wife picked out, I am
really bad at selecting complimentary colors!



So here is the question. If an owner would want to run the amps for a long
time, you have to consider tube availability.  The 8874/3CX400A7 is listed
at $895 each at RF Parts, so I was wonder about re-tubing?



I searched the archives and found a discussion/argument from February of
2002.  There a GI-7B was being discussed, but no results were ever posted.
Now, 12 years later, have any on the list come across a tube that can be
considered an available replacement with new sockets, for the three 8874's
currently in place?



I would greatly appreciate any advice available,  Thank You



Chuck  W9KR

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