K1 - RTFM (or how jumping to conclusions can waste two hours)

See if you can spot my deliberate mistake. Today it was time to align the Filter Board for transmit. I rigged up a dummy load and power meter, and put the K1 into Tune mode, starting on 7MHz. Yippee! About 1.5W output versus the nominal 2W; so I followed the instructions in the manual, gently tweaked the relevant trimmer capacitors on the Filter Board and power came up to 2W plus. I moved on to 10MHz, where again power started out at above 1W and a bit of trimming quickly got me to 2W .

Next, I switched bands to 14MHz. Tune mode on and, oh dear, almost no power output; barely enough to nudge the power meter needle off its stop. Ditto at 21MHz.

Now, the troubleshooting instructions do cover a situation where 2 bands work and 2 bands don't. And this led me to 2 hours of checking the soldering, checking component values and getting my oscilloscope out to do some signal tracing. There were some big differences in the RF voltages all the way back down the transmit chain. But what was baffling was that (a) everything peaked up on all bands on receive, but (b) with no power output on just 2 bands, it felt like a "binary" problem, something to do with relays in the Filter Board not switching properly.

After two hours, and with a headache coming on, I decided to call it a day at the workbench and read through the manuals one last time; I wanted to draw up a list of "back to basic" checks and signal trace tests on both receive and transmit that I could run through tomorrow. While doing this, I noticed a comment about making sure that the trimmer capacitors are all properly peaked.

I must have looked at this same sentence 10 times during my testing today. But it suddenly struck me that, when I first measured zero output on two bands (compared with the 1W plus I had started with on the other bands), I had jumped to the conclusion that there must be a definite fault; so I had never actually tried adjusting the relevant trimmers to see if that would bring up the power.

Which, of course, they did when I went back to the K1. Oh well, put it down to experience, I guess. I'll finish the fine tuning tomorrow.