New perspective? Re: [1000mp] Sticking relay problem

[W0UN -- John Brosnahan]

 >Therefore, I suggest that the relay/switching problem may be related to
 >excessive RF in the shack and/or ground-loop situations which may not be
 >enough to prevent loading and apparently successful operations - but may be
 >enough to affect the relays or their driving circuitry. This might also
 >explain why shops, using good antennas and/or dummy loads (and probably no
 >linear) might have difficulty recreating the problem observed by the
 >equipment owner.
 >

Scott--I appreciate all of the insights that might help me solve
my problem as well as the others who have a similar one (but I
wonder if it is the "same" problem).

In my case the radio was used as the K3LR 160 contest rig and
had a number of good years of intermittent contest weekend service.
I bought it from Tim when he upgraded to Mark Vs.  My plan was
to use it as the IF for some serious, weak-signal VHF/UHF transverters.

The radio was never used on transmit for the first year I owned it.
And the problem began occasionally appearing after the first year,
still before I had ever tried to TX with it.

The problem is on both RX A and RX B channels and is independent
of whether the antenna tuner is in or out as well as being unrelated
to the band selected.  And when I did a quick check a week or so
ago to see if the problem was also on the RX Input it appeared that
it was.  In re-testing the rig tonight I realized that to get to the RX input
that I had used a stereo cable and used one color on one end and
the other color on the other end.    OOPS!     So, when I hooked it
up correctly I DID have the RX working in the RX Input jack.

(My explanation for the screw up is that it is dark behind my rig and
impossible to get the rig out far enough to see what I was doing.
I managed to find the right phone jack by feel.  But my sense of
feel does not include COLOR.  So I plugged in the wrong color
cable of the stereo pair.)

This is great news since it greatly limits the area that needs to be
checked.  And since it is the same with either Ant A or Ant B and seems
to have no correlation with whether the Tuner is in line or not then
it appears to be in the T/R relay or closely associated circuitry.

Others have described how their rig works in Ant B but not in Ant A--
or it is at least intermittent in Ant A position.  It appears that all of
these relays are of similar design although the T/R relay is a different
model number than the others.

So the troubleshooting will include RL6016, the T/R relay, and the
associated driver, cables, circuit board traces, etc.  While there
are a LOT of relays on the LPF board(which includes the T/R relay)
most are used to switch in filters and do no pass the Occam's razor
test since MY problem is on ALL bands.

Maybe this weekend!

--John



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