[Elecraft] K2 Only 30-metre Band Works

[VA1CQ]

Hi Geert,

Coincidentally, while troubleshooting today I was listening to relays! 
There is a different sound depending on whether one relay clicks or more 
than one clicks. Yes, there are relays clicking as I change the band. A 
different number of relays operate depending on which band you change 
to. The schematic shows which relays close as you change bands. I was 
suspicious that maybe the necessary relay contacts were not closing. If 
there is relay closing trouble, this could explain why the different 
bandpass filters are not working correctly.

Some history. I bought this K2 new in 2008. It sat unbuilt for about 10 
years. I then built the Control board only. After that a couple more 
years passed. Just this year I built the Front Panel and RF boards. 
Therefore all parts are at least 13 years old. I wondered if over that 
time perhaps the relay contacts may have aged through lack of use.

Today I now have 80, 30 and 15 metre bands working. I was able to tune 
the matching bandpass filters to get the correct transmit output power 
on each of these bands. But I still cannot get 40, 20, 17, 12 and 10 
metres to function. I did some resoldering and even took off the 
heatsink to examine the underside of the RF board.

I did more voltage checking today. I came to no conclusions but I still 
am wondering why the 8 volt bus is only 7.6 volts and whether this could 
be an issue or possibly cause unpredictable switching.

I will continue studying the relays further in my next troubleshooting 
session.

73,
Murray VA1CQ


-- 
This email has been checked for viruses by AVG.
https://www.avg.com