KAT500 single band fault
Consulting the hive mind:
I have for many years used the K3/KPA500/KAT500 combination at home and on 6Gs DXpeditions. It has been faultless until this week.
Setup: On all bands 20-6m I use an Ultrabeam antenna (same principle as Steppir) so the KAT500 is set to Bypass. SWR ranges up to 1.2:1 depending on frequency and band
Symptom: the KAT500 and KPA500 fault with High SWR. The LEDs show 3:1. This only happens on 12m; other bands work as expected
Fault finding so far: antenna analyser on the Ultrabeam on 12m shows SWR of 1.2:1.
Suggests antenna OK, so replaced antenna with dummy load: KAT500/KPA500 fault as before on 12m only.
Antenna had been connected to Port 2 of the KAT500; dummy load also connected to Port 2.
Moved dummy load to Port 3. Setup runs as normal. Moved antenna to Port 3. Setup runs as normal across all bands 20m-6m.
Conclusion: there is a problem with Port 2 of the KAT500, but only on 12m.
Suggestions of how to troubleshoot this Port 2 issue with KAT500 gratefully received!
BTW, I built all my Elecraft products from kits, so happy to open up the box and do board or component level troubleshooting/replacement; I just need guidance on how to nail down the problem.
73, David G3WGN M6O