[TenTec] SSB Problems - almost oscillating?

[Rick at dj0ip.de]

Hi Sam

The VERY first thing you need to do is put the radio on a dummy load and see
if you still have the problem.
Of course if you rely on someone elsewhere listening to your signal, then
you will need someone very close by with a receiver.

With an antenna under the roof, you should automatically that you have RF in
the shack.
You must use an RF choke.  Insert it as close to the radio as you can
(direct attachment).

You will probably be OK just using a Maxwell choke from THE WIREMAN (Model
8232), but a home-brew Guanella choke would be better.
You didn't say what band(s) you are on but if it includes 80m then wrap 17
turns of RG-58 onto an FT-240-43 Toroid.
You should cross-wind using the Reisert method.  This puts 8 turns on each
half of the core with the 9th turn being the fold-back winding.

AND (simple), for whatever band you are trying to work, cut yourself a 1/4
wavelength of hook-up wire to use as a counter-poise.
Simply connect one end to the chassis (GND terminal) of your Omni, and run
it around the room, directly on the floor.  (Insulate the far end with tape
or nail-polish).  DO THIS FIRST!  (Even though I listed it last.)

73,
Rick, DJ0IP
(Nr. Frankfurt, Germany)

-----Original Message-----
From: TenTec <tentec-bounces at contesting.com> On Behalf Of Sam Bradshaw
Sent: 10 March 2018 17:15
To: tentec at contesting.com
Subject: [TenTec] SSB Problems - almost oscillating?

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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