[TenTec] SSB Problems - almost oscillating?

[Sam Bradshaw]

Hello TT reflector, I'm a new(ish) owner of an old TT Omni-A that I got
from a silent key sale.  While I really enjoy this rig, I've been having a
few issues with it that I wonder if anyone here has encountered and have
any starting points for me to check.

First off, my ALC LED is not functioning correctly(led is good).. I think I
may have found at least a partial issue with this(bad 1N748 diode on the
Low Level Driver board, labeled D5? showing current both directions), it
makes diagnosing my other issue a little more difficult.

  When transmitting SSB with my Shure 450 mic(on HI-Z), if I take the drive
past 1 or 2 on the scale(showing very little output on the watt scale on my
autotuner), I have recieved signal reports from checking into some nets on
40M that say it sounds like I have RFI entering my signal.  When this does
occur, I do notice that my frequency fluctuates by several Hz(there is an
AADE digital readout installed in place of the old analog scale). While I
am sure it is entirely possible that I am getting RFI from my antenna
situation or elsewhere (antenna is an attic-mounted MFJ G5RV Jr. fed with
RG-8), i never had an issue with my prior HF rig(an old Heath SB-100) with
the same mic/antenna setup.  The even more interesting issue is that this
unit seems just fine making contacts on FT-8 Digital mode(shows full output
on my tuner if i take it past about 1.5 on my drive dial!), which I know
uses SSB.

   The only test gear I really have access to is a DMM and the station
monitor from the Heathkit, so I'm kinda limited from what I can check out.
Other than that seemingly bad 1N748 on the low level driver board that I
having had a chance to change out, no caps appear blown/leaky and most of
the resistors I have been able to check have been just fine. Other things I
have done were to remove most of the boards from their connectors and
clean/reseat them and make sure all ground connections are good.  The only
other thing I can think to mention is that I currently do not have my
station grounded to earth.. I was basically told by many over on QRZ.com
that it probably wasn't worth grounding since I would need to run around
30ft. or so of wire from the shack to a grounding rod outside.

   Thanks for taking the time to read this and any advice/stating places to
check would be much appreciated!

      73 DE Sam,
          W8SJB.

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