Yesterday afternoon 15-meters opened and I started to call a station only to
find that I had very little transmitter power out. Everything seemed to be set
properly so I cycled the DC power and bingo I had proper output. I chalked it
up to cosmic rays (W8JI knows what I'm talking about) and went on the make the
QSO. I tuned around a bit and found that 12-meters was open, found another
station and started to call him and once again very little output.
I did briefly notice on the display an ERR message indicating a TX gain
failure. Going into Tune, I could only get about 40 W out while calling for
100. This varied from band to band, with the lower bands actually being worse.
So I decided to run the TX Gain calibration. The first step on 160-meters
failed at about 3.7 W.
Since I had the latest beta firmware installed, I decided to roll back a couple
of versions. No joy. Time to take the lid off and look around. I poked at
all of the cables and the lead from the KANT3 board to the coax connector,
which all seemed to be well-seated.
I contemplated removing the 100W PA, but logic said that it should be okay
since it did make output more-or-less proportional to the apparent drive
available. Time to run the TX Gain cal one more time before going further.
This time it failed at 2.4 W on 1.9 MHz. Taking the lid off and poking around
had made a difference.
I won't bore you with the rest of the two hours I spent investigating this and
will cut to the chase. Removing and replacing the KANT3 board fixed the
problem. Apparently, there was a problem with the interface connector between
the KANT3 board and the main r-f board.
I had a similar problem with my old TR-7 years ago. The digital display would
get intermittent and required accessing the daughter board and moving it up and
down on the interface pins to scrub off the oxidation. This would last about
three or four months until I had to do it again.
I hope this isn't going to be a recurring issue with the K3.
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