I like the 76 family, own a CA 3 holer and have worked on many for
customers.
New HV electroytics would be cheap insurance plus the ones in the 28V and
time delay (tantalum, replace with low ESR electrolytic) circuits. Check the
tolerance of the equalizers and a few other resistors on the PC board that
tend to drift or cook, especially R-116 (use a 1W) and a 3.3K 2W right in
the middle of the board, forget the R #.
The main power relay likes to weld contacts, its cheap but a PITA to
replace.
Another weak point is the bypass caps at the base of the plate choke and the
"VHF" choke. Use .01/6KV discs if 160 will be used a lot or .0047 otherwise.
Replace the VHF choke with a 15 Ohm 20W real wirewound which will both act
as a VHF choke as it has the right nichrome inductance and as a surge
suppressor in case of a tube arc. Ive been stressing that resistor ever
since I was told its purpose back in 1963 on the NCL-2000. Very few amps use
it but its finally starting to be picked up by some ham amp manufacturers
who must read this forum for ideas (-;
Thats enough for now. There is a potential band switch problem but lets
leave that until you get the amp and do the basics.
Carl
KM1H
Amp repairs and 6M conversions since 1964.
----- Original Message -----
From: "Charles Hedrick" <cchedrick@gmail.com>
To: <amps@contesting.com>
Sent: Tuesday, August 30, 2011 6:43 PM
Subject: [Amps] Alpha 76
>I just purchased an early single meter Alpha 76 and await it's arrival.
>I'm
> informed by the owner the amp was stored some 12 years ago in his home and
> had only about 30 hours of use since he bought it new. He sent me
> pictures
> showing the voltages are correct still! Well, I figure new caps, and a
> disassembly/cleaning of the blower. Any other suggestions? Oh he's
> shipping in three boxes....hopefully it will still be 9/10.
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