Id say that the amp was the recipient of excessive drive at some point as a
prior owner believed that another 200-300W would make a difference. Ive seen
that desoldering as well as crystalized solder joints in the bandswitch area
in several amps that were ridden hard and put away wet.
Im also a happy 76PA owner on the 2nd station. It was a former contest
station amp from one of the Carribean big gun multi-multis and required a
lot of TLC to get it back to its former glory. Thanks to my scrounging
ability it was rather painless (-; plus it came to me as payment for fixing
their Ten Tec Titan 425.
Carl
KM1H
----- Original Message -----
From: "Jeff Blaine" <keepwalking188@yahoo.com>
To: <amps@contesting.com>
Sent: Thursday, September 16, 2010 1:01 AM
Subject: [Amps] Famous Alpha plate clip desoldering issue
>I picked up an old 76pa which seems to be in otherwise FB condition. 2400v
>idle on the plate cooking away those pipes who have not been used in a
>couple of years prior to some initial power testing tomorrow.
>
> Only strange thing I noticed on the inspection was that every single one
> of the braid connections to the plate cap had delaminated. The braid is
> tarnished so I assume it's silver plated - hard to tell the condition of
> the solder connection otherwise. But the braid was lose enough that the
> cap could be removed from the braid just by bending the braid slightly.
>
> I got to thinking about what could have caused that. Came down to one of
> three possibilities:
>
> 1. The famous alpha plate clip desoldering issue, known world-wide to all
> Alpha owners but not to nubees who expect these things to be soldered in
> the traditional way. Not to worry though because....
>
> 2. The amp creates a virtual short when keyed down due to it's massive
> high power output only to have the joint break again with key up. A
> technology known only to Alpha and is top secret such that RF Concepts was
> unable to dig the secret from the ETO data archives. The secret sauce
> lost for all time.
>
> 3. OR - The dogs were whipped mercilessly at one time, so hard that their
> anode temp rose high enough to desolder, AKA SB220 pins can sometimes do.
> Say it's not so!
>
> Hoping some of the learned 76 owners may have some insight.
>
> There was some what appeared to be "melted" gasket material visible on
> each tube. Maybe 1/4 in long and a tiny fraction of an inch in height and
> depth. I say melted because it was stuck firmly to the tube and rounded
> and shiny on the exposed surface. Interesting because the sealing
> material will break with age but in that case it generally has a rough and
> "flat" appearance.
>
> 73/jeff/ac0c
> www.ac0c.com
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