[Elecraft] Strange receive problem

[Geoffrey Mackenzie-Kennedy]

Joe N9JR wrote on Saturday, April 22, 2006 11:10 PM

>  I have an issue on 30m receive only.  When I transmit on 30m I get full 
> power, and it receives normal,  but after a while it loses most of its 
> sensitivity.  Transmit again and it will hear the other side of the earth. 
> I have noticed that once it goes partially deaf I can get a High Curr 
> indication on the first dash I send, but after that it puts out full power 
> with no complaints and of course after every transmission it is that 
> beautiful K2 receive.

I had the same problem with 40m 18 months or so ago and posted comment on 20 
November 2005 when Mark, KJ7BS, experienced a similar problem. In my case 
the problem was caused by a 'dirty' contact of K1 in the BPF. Although 
problems with bifurcated 'wipe clean' contacts in sealed relays very rarely 
occur, they can arise.

 >  I think we can eliminate the BPF as nothing changes in it for either 30 
or 20.

Perhaps. When your receiver goes partially deaf on 30m, have you tried 
switching to 40m (not 20m) and back to 30m to see if the receiver recovers - 
without transmitting? This would exercise K4 in the 20m / 30m BPF. If the 
receiver recovers then K4's contacts become possible suspects. If it does 
not recover, then the BPF assembly is likely to be OK.

73,
Geoff
GM4ESD