[Elecraft] KAT-500 Issue!

[G3RTE]

I have had the KAT-500 for many years and has been very reliable despite 
the abuse I have probably inflicted on which will become apparent.

Recently when using the KAT-500 I have noticed from time to time a 
fizzing noise. Wasn't sure where it was coming from. Then a couple of 
weeks ago I heard a load pop coming from it. However all seemed sort of 
okay. I took the top cover off and saw straight away that the 2 green 
wires. I think those are the ones in circuit diagram A-A, B-B, had fused 
together and possibly the popping sound was the wires short circuiting 
or flashing across. There was some residual burnt insulation on the 
board. It still seems to work apart from changing aerials. If for 
example I have been using Ant 2 say my 10m aerial and I switch manually 
to Ant 1, my 6m beam. When I apply power the aerial switches back to Ant 
2. When I manually switch it back to Ant 1 all is fine! In the grand 
scheme of things I can live with it. Getting Elecraft equipment repaired 
in the UK is nigh on impossible now and it has to sent off to Italy. Not 
easy as a friend of mine found out.

So any ideas as to what might be the problem?

73

Jim G3RTE