The problem is the tube socket itself. Upon magnified examination I
observed that the inserts for the tube pins have been mangled by someone
pushing
something down into them that spread and twisted them and all but
eliminated the nice "friction fit" around the tube pins. As a result the tube
fits
too loosely and occasionally loses contact.
I have it working on a semi-reliable basis (which allowed me to
complete the alignment.....and how far that was off is a story in itself) but
since I have a replacement tube socket already on the way I'll leave the
receiver on the bench until I can do the swap-out.
SIDE NOTE: I bought four receivers over the past 2 months but *ONLY
ONE* has operated flawlessly from Day 1 with no work having been done on it,
and that one is the 1961-vintage 2B, s/n 2052, which means it was the 52nd
unit built. All three of the R-4A's have problems, problems......... ;-)
Hmmmm, from a longevity standpoint maybe Drake should have quit while
they were ahead..... ;-)
73/arf,
Paul, K4MSG
In a message dated 9/15/2010 8:22:21 P.M. Eastern Daylight Time,
gswy...@durham.net writes:
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_ (mailto:ph...@aol.com)
To: _drakel...@zerobeat.net_ (mailto: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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