[TMC] GPR90

[Ed Tanton]

RESTORE IT Mike-it's a GREAT piece of gear!!!

FIRST: Do NOT just plug it in and turn it on. Bring it up on a variac over 
a period of time. Start at 20-30VAC, and bump it by 10V no more quickly 
than once an hour. Let it sit at that new voltage another hour... etc. This 
should reform any electrolytics that need it. Sometimes they do, sometimes 
they don't. The hard way to find out is to have one short and take your 
power transformer with it. Listen for frying noises each time you step that 
voltage up. It's easily recognizable.

After that, it's a matter of replacing any bad components-such as (although 
I have never heard them specifically associated with GPR-90s... but it's 
the same timeframe)-Sprague 'Black Beauty' Tubular Capacitors in it-replace 
them ALL with 'Orange Drops'. Many of the resistors will have changed 
value-but I'd start with the tubes and see just how it is performing, 
before I'd get too deep into component values. You can buy tubes and parts 
from Antique Electronic Supply (<http://www.tubesandmore.com>) and I 
imagine you know of others.

Please let me know how it goes, and if there is any way I can help.



73 Ed Tanton N4XY  [TMC] Reflector Manager

<n4xy@earthlink.net>

Ed Tanton N4XY
189 Pioneer Trail
Marietta, GA 30068-3466

website: http://www.n4xy.com

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LM: ARRL QCWA AMSAT & INDEXA;
SEDXC NCDXA GACW QRP-ARCI
OK-QRP QRP-L #758 K2 (FT) #00057

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