[Elecraft] K2 Relay contact resistance

[Stewart Baker]

Having decided to join the melee trying to work 3Y0X on Peter One Island, I 
dusted off my FT1000MP. The only time that I use it are on occasions such as 
this when a separate receiver is useful when working split.

I noticed that the receive sensitivity was varying on 20 & 40m, and traced this 
to the HPF board at the front of the receiver. This board contains 8 miniature 
relays which do the filter switching. If I tapped the board the received signal 
strength varied. From notes I found on the web this is a known problem where the 
solution is to change all 8 relays. I didn't fancy changing these small relays 
if there was a better solution.

I remembered that the FT102 had big problems with people were changing relays by 
the bucket full. Yaesu don't seemed to have learned the lesson of the FT102 ! 
A local amateur came up with a fix which consisted of running a small DC current 
through the contacts to break down any oxide layer that had formed over time.

This morning I modified the HPF board to run about 1mA through the contacts.
10 resistors and 2 caps later - End of problem - Fixed.... 

The big relays in the KAT100 should not have a problem, but what about the 
smaller ones in the K2, KAT2 ? As far a I can tell a number of these have only 
very small AC signals passing through them. None have any DC current flow.

It took about 7 years before the problem surfaced with my FT1000MP, I would be 
interested in comments on whether in the same time scale I might expect to get 
similar problems with my Elecraft gear.

73
Stewart G3RXQ