Hi Paul,
Years ago I purchased an old Heathkit SB-102 transceiver as a back-up set, and
all was well until one day it stopped "hearing" on CW on a consistent basis.
There was an intermittent that drove me nuts!
I checked the schematic for all of the usual "suspects", and determined that
the issue was with the crystal oscillator/BFO stage---I even pinpointed (on
paper, anyway!) the exact area where I thought the trouble was coming
from...yet to the eye everything looked A-OK, & the components checked-out.
The design of the thing incorporated printed circuit mounted tube sockets. In
desperation, I re-heated just that contact point at the socket that I thought
was causing the intermittent. Lo & behold, I guess the heat caused enough
solder to flow in the socket that bridged the gab, & the intermittent was gone
forever.
I think re-heating those socket pins is probably a good idea.
~73~ de Eddy VE3CUI - VE3XZ
********************************************************
----- Original Message -----
From: ph...@aol.com
To: drakelist@zerobeat.net
Sent: Wednesday, September 15, 2010 3:49 PM
Subject: Re: [Drakelist] R-4A anomoly
Just to reiterate from the original email: Different tubes *WERE* tried
(including two NOS) and loosening/tightening the tube socket & PCB mounting
screws. More work on this tonight.
Meantime, I ordered a new 7-pin, bottom-mount-with-grounding-lugs socket
from Antique Elex and if worse comes to worse I'll just replace the socket. It
is possible that one of the socket pins has actually separated into two pieces,
upper & lower, that lose contact when the tube heats the socket and the metal
expands and changes shape. It's rare, but I have seen it before.
And I'll stick an extender in it tonight and compare voltages top &
bottom.
73/arf,
Paul, K4MSG
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