[Elecraft] K1 - low DC voltage readings, AC hum when peaking caps, low output power

[David Swain]

When performing DC voltage tests on page 46 of the K1 User's Manual, four test points measured lower than the values specified in the manual:
J7 pin 1
U9 pin 3
U9 pin 6
U9 pin 7

Also, I noticed quite a bit of hum coming through my headphones when I peaked the 4-band filter board for transmit using TUNE mode. The hum was only at the very peak. I did not hear any hum in receive mode.

Finally, on page 19 of the KFL1-4 manual, I read "Set power output to 5.0 watts using the OUT menu entry, then exit the menu. Enter TUNE mode briefly on each band. The wattmeter should indicate approximately 5 watts." I never read 5 watts. My power output as shown in the OUT menu was getting reset to a much lower value. Inspite of exiting and reentering the TUNE mode, I couldn't get a 5 watt reading. My output kept getting reset.

I wrote to Elecraft Tech Support and Gary pointed me toward my cheapo power adapter. He advised using: "a well-regulated DC supply of at least 2A capacity, since the rule of thumb for most DC supplies is to use one with some reserve current capacity to insure long life, good regulation, and good filtering."

I searched the Elecraft email reflector for power supply recommendations, and found many excellent suggestions. Finally, I chose what I felt best suited my immediate needs (RadioShack 22-504, 3-Amp Regulated Power Supply, 13.8 VDC). After I connected it to my K1 all the problems mentioned above vanished. I now have correct voltage test readings, no hum on trasmitter peaking in TUNE mode, and approx. 5W output readings.

Thanks again to Gary, and to all those who posted their ideas on power supplies for the K1 and K2.

73
David KC9AWM

-- 
David Swain




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