Receiver Signal Attenuation When Keying The Microphone Or Rocking The Bandswitch; Vox Trip Problem; Maintenance Procedures; Vfo Lubrication - Kenwood TS-830 Survival Manual

7.24 Receiver signal attenuation when keying the microphone or rocking
the bandswitch
Question: I have a problem with my Kenwood TS-830S. After tuning up, when I key the
microphone, the receiver signals are sometimes greatly attenuated. When I rock the bandswitch
slightly, the signals come back at normal reception / sensitivity levels. I think I recall there was
a somewhat common problem with the bandswitches in these rigs. Or is this just a matter of
getting a cleaner on the bandswitch contacts. Any suggestions on what might be causing this,
and how to fix this? Also, any recommendations on a specific brand of contact cleaner to use for
switch contacts / potentiometers in general? (George N0GH)
Answer 1: Tech Spray and GC make some good contact cleaners that seem quite non-
destructive in general, and I've had good luck with them. They are available at many
TV/electronics repair/parts shops. Be careful when using any kind of contact cleaner with these
bandswitches, though. It's easy to do more harm than good, and some "horror stories" have been
reported. Might be best to try to isolate the particular section of the switch that's causing the
problem, using a small insulated stick (like a thin wooden "Q-tip," using the non-cotton end) to
gently press suspect contacts on the switch against the rotor of that switch section. If you can
find the specific wafer, or side of a wafer, that has the problem, possibly the bad contact can
simply be pressed back into proper position, or very gently cleaned using a Q-tip and isopropyl
alcohol, which seems pretty benign. (Steve WB2WIK/6)
Answer 2: Another likely candidate in the 830 for the type of problem you describe is the
transmit/receive relay. Pop off the clear plastic cover after unplugging it and gently clean the
contacts. Be very careful not to bend the reeds. A high resistance from a dirty contact here can
really attenuate received signals. A business card soaked with contact cleaner or alcohol works
nicely. Don't use anything abrasive. (K0RS)
7.25

VOX trip problem

Question: I recently acquired a TS-830S. I have made a few "enhancement" mods for CW but
have one problem that still needs a fix. When moving the mode switch between CW-W and
CW-N, the VOX frequently trips, even with the VOX gain in the minimum position. I know of
two other 830 owners that have this problem and live with it. I work 95% CW and the problem
is annoying so I would rather fix it. My initial inclination is to reduce overall gain of VOX amp,
regardless of impact on SSB VOX operation, but this might be taking the wrong approach. I do
not own a scope, so I am flying blind re transients. (N4EX)
Answer: I used to have the same problem with my TS-830S and was able to cure it by cleaning
the mode switch several times. This is easier said than done. The switch is pretty tightly sealed
and cleaning requires locating an opening into the case and injecting cleaner into the switch.
Operate the switch gently through all of the positions - 20 to 50 times is not too many, and let
the rig sit overnight to dry out. I apologize if this response seems overly simplistic, but time
takes it's toll and I've seen a lot of strange symptoms fixed by elimination of dirt, oxidation, and
poor connector contacts. (W8RDH)
8

Maintenance Procedures

8.1

VFO Lubrication

The factory does NOT lubricate the VFO tuning-shaft's concentric bushing-bearings or the
VFO-gearbox. In time, this will cause premature wear and play in the drive system. After
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