K1 Assembly Complete

I completed and installed the two coils in 50 minutes.  I then spent another 40 minutes doing the TX tests and alignment.  That brings the total time to 25.75 hours.

The initial transmitter testing went well, with coils almost peaked already from the RF alignment on both 30 and 20 meters.  After TX offset calibration, I was able to produce 7 watts out on 20 meters, and the signal sounded great on a monitor receiver.  At 7 watts output the K1 is consuming 1.0 amps.

However, things aren’t so rosy on 30 meters.  While the 2.0 watt calibration went without a hitch, I was not able to produce more than 3.0 watts output (measured by both the internal meter and an external QRP meter).

My K1 Filter Board kit was shipped with 2 small toroids and 2 larger toroids, rather than 4 small toroids.  Those toroids form the output filters, which is not adjustable.  I spoke with Elecraft about that, they were confused as to why, but said to use the larger toroids on 30 meters.  I ran the math, and the larger toroids needed 2 fewer turns.  Elecraft suggested removing only one.  So that’s what I did.  These larger toroids were used on the 30 meter band. My initial suspicion is that the lack of transmitter power is due to problems with L9 and L10, the output filter.  Since that time, I’ve purchased some replacement cores, so I may just wind them again on the correct size toroid (if there is enough magnet wire left).

I was hoping the mystery noise would go away when everything was tightly screwed together, but it hasn’t, and it appears substantially worse on 30 meters.  I reprobed EVERY component lead mechanically and was not able to produce any noise.  I highly doubt it is a solder connection for that reason.  I still suspect bad power supply noise.  Now that the kit is complete, I’ll start to chase that down.

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