[Elecraft] K3 intermittent RX drop-out

[Stefan Heck]

Hi gents,

Since fall 2011 I am happy to own the basic version of the K3, with the only
extras being the KXV3A transverter interface, some CW filter and the KDVR3
voice recorder. I have been using the K3 once or twice each month only as IF
unit for a 2 m XVTR. So I am not using the SO-239 rear socket. The K3 worked
very fine for almost 2 years but started then to exhibit intermittent
drop-outs of the RX signal. The path was not completely gone, just had extra
attenuation of 30-40 dB. Transmission seemed never affected. Initially it
resembled a hanging contact of a T/R-relay, and could be cured by pushing
the PTT once or twice. 

 

But during the first hilltop operation after the winter the problem was
permanent. Back home in the shack the problem was still there but went away
by itself after some hours of warm-up. I tried to identify the failing stage
but never got to the bottom of it before it disappeared. But I found the
extra insertion loss is way down into the receiver, probably at the second
IF level. During a second hilltop operation the problem surfaced again. Back
in the shack the failure was present only for some minutes before it
disappeared. While it persisted, I could not detect any effect of tapping
somewhere on the chassis.

 

I have read some earlier reports of similar malfunction in this forum, and
will take a closer look at all connectors. I will also try to reproduce the
problem by using freeze spray, because I suspect it could be related to low
temperatures.

 

I would appreciate to hear if anybody else has observed such behavior and
was able to pinpoint the failing part or contact.  

 

73, Stefan (LA0BY)

 

Email la0by >at> darc.de