[Elecraft] [K2] POWER control has no effect on actual transmit power

[Ben Byer]

I've had fun putting together K2 #7373, and am finally at the point of doing the 40-Meter Transmitter Alignment (manual, p.78).   I have the unit connected to a 50-ohm dummy load, and am trying to tune L1 and L2 to show 2W on the internal wattmeter.   When I press TUNE, the measured power ranges from 0.2W-0.4W.

I can adjust the POWER knob to show 0.1W - 15.2W while the unit is idle, so the knob reading circuit works -- but adjusting the knob doesn't change the reported transmit power even slightly (remains 0.2W-0.4W), and neither does adjusting L1 or L2.

I suspect that the measurement is correct, because the overall unit power consumption is measured as 11.9V 0.20A when idle, and 0.42-0.44A when in TUNE mode (regardless of what I set POWER to before enabling TUNE -- same result with 0.1W vs 15.2W)

I already checked the voltages on RF Q5, Q6, Q7, and all seem reasonable.  (Actually, initially I measured 0v on the Q6/Q7 collector during transmit, and discovered that I had swapped two wires on T3.   Fixing that brought the voltage up to almost 12v, but did not change the transmit power).

Any suggestions?

Thanks,
Ben (KJ6ZGJ)