K1 Transmitter Alignments

I was just about to panic when I first set the K1 into TUNE mode. I have hooked up the K1 to my variable power supply, set the current limiter to 1 amps (as instructed by the manual), turned the K1 on and set it into TUNE mode. The only thing that happened was that the K1 turned off and the current limitin led on my power supply was lighting up, meaning that the K1 wanted more current then it was given.

I tried to give it more current, but there seemed to be no limit on how much current the K1 wanted. Above 1.25 amps the K1 could stay turned on, but the behaviour did not seem normal at all. It should not draw so much current, since the transmitter is actually off with the initial power setting at 0.0 watts and the filter board missing. Something was very wrong. I tried to do one or two voltage checks but, of course, they were way out of range.

I started to look for bad solderings, misplaced and missing parts and suddenly I noticed that D11 was mounted reversed… I unsoldered it and remounted it, this time on the bottom side of the PCB because the top side got slightly damaged. Turned the K1 on and suddenly it looked much better…. phew….

Voltage checks were perfect and the transmitter alignment procedure went fine, too. The built-in instruments in the K1 are really priceless. The TX offset adjustment went good, too.

Unfortunately, I have to go to bed soon so I will not be able to do the final assembly now. Consequently, I won’t be ready for EQP 2006 but I gave that up anyway several days ago because of the cold weather; I would have to put up the DX-88. There are also a few fine tunings that I would like to do, before going on the air with the K1. These would include:

  1. Redo the TX filter alignments using a wattmeter, like the WM-2.
  2. If there is adequate power to spare on 17 meters, optimise the filter for RX as suggested by the manual. How to do this best? On the air comparing to another RX?
  3. Recheck the TX offset setting. Instead of listening to the two tones, I can try with an audio oscillosope as well.
  4. Calibrate signal strength meter?
  5. Measure crystal filter widths using the NG-2.
  6. do some general measurements, like power output, current consumption, etc.

Author: Alexandru Csete

Embedded software engineer in the satcom industry during the day. Radio amateur and SDR hacker during the night.