[CQ-Contest] TS-940 heat problem

Eric Scace scace at uu.net
Sat Jun 20 05:09:37 EDT 1998

Has anyone encountered the following problem with a Kenwood TS-940 and
found a solution?

-- turn radio on cold.  radio works fine
-- after 10-15 mins, receiver starts squealing... at first intermittently,
then more or less permanently.
-- after 1-2 hours, squeals stop & radio seems fine thereafter, at least on

The squeals seem to be from an oscillator going haywire.  The oscillator is
in both the xmit and rcv chain, as no signal can be xmitted during

I suspect this is a temperature problem somewhere.  Time to onset of
squeals is delayed when top cover is removed, although the problem
eventually does start up.  Squealing begins before first power supply fan
cooling cycle starts, but does not stop when fan cuts off.

Changes in room temperature have no effect.

Blowing air across the top of the radio with a room fan seems to also
extend the time before squealing begins.

If someone has debugged this problem before, I'd like to know the details
of the solution.

Suggestions also welcomed!


-- Eric R3/K3NA

scace at uu.net

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