[UK-CONTEST] K3 working again

[Chris G3SJJ]

Firstly thanks for all the comments and suggestions. Here is the story for any other K3 owners who experience the problem. Initially I was hesitant to 
accept that the fault might be a poor contact on a connector pin, however I called in at the local Maplin store and bought a £3.50 can contact 
cleaner. Spread the ESD mat out and wired myself up to it! Removed both KSYNC3 boards and the KREF3 board, examined the surface mount soldering 
carefully and then sprayed the pins on the PCB connectors.

On re-assembly the fault was still there! That is, no rx /tx and PLL1 & 2 display showing either 7.4 or 0.0. By chance I happened to tap the TXCO, 
which is the metal can component on the KREF3 board, and the fault cleared. The pins were quite sloppy in the DIL carrier so I bent them very slightly 
to make a more solid fit. I have had the radio on soak test now for several hours now and it is very stable.

Gary at Elecraft suggested checking the output from the KREF3 board. You should see about 2v pk-pk at 49.380MHz. I checked this on my ageing frequency 
counter and Tektronix 435 scope. The signal disappeared when the fault occurred confirming the TXCO wasn't oscillating.

A tip - Instead of trying to get the scope probe down the TMP mini coax sockets, I used a spare patch lead supplied with the 2nd rx kit. Plugged one 
end into the socket and clipped the probe on to the other end.

A satisfactory conclusion all round!

Chris G3SJJ