[Collins] re. Collins 30L-1 misbehaviour

[Hans Zimmermann]

Peter:

are you really sure it is the 30L-1 that causes the loss of the RX signal ?
Does it never occur when the 30L-1 is not connected ?  

I am asking, because I faced a very similar problem just recently: RX
signals were extremely weak (no change if antenna was connected or not), but
got suddenly better each time after tuning the 30L-1. This looked like a
corroded-contact-problem, so I located, checked and cleaned all the 30L-1
and also the KWM-2A relays (quite a job to get to all of them), only to find
out that the real cause was a microscopic crack in a solder joint in my
outside (antenna) coax switch (apparently caused by mechanical metal fatigue
at one jack). I re-soldered the joint and now it's all ok. The tuning or
transmit signal apparently "welded" that crack temporarily, but after a few
days without operating it was again open. 

Another idea: Is the AC line voltage marginal, and switching on the 30L-1
reduces it so that a possibly corroded rely contact in the transceiver (not
in the 30L-1) is no longer pressing hard enough ?  I had such an effect with
a coax relay used with another rig a long time ago, in a qth with
occasionally marginal line voltage.

These might not be the problems in your case, but I learned from it how
important it is to have a very close look at absolutey everything in the
signal path...

73
Hans, HB9AQS

You wrote (Digest 312):

...
My 30L-1 developed an intermittent nasty habit in attenuating my receive
signal badly as soon as the power switch is on, even without keying the
amplifier.
I suspected dirty relay contacts, but why would this happen by only
switching the power on, without keying the amp ? The drop in receive signal
strength is very noticeable and returns to normal as soon the on / off
switch is in the off position.