K2 VCO Alignment Issue

Posted by John Wingard on Apr 27, 2019; 5:32pm
URL: http://elecraft.85.s1.nabble.com/K2-VCO-Alignment-Issue-tp7651214.html

Working on my 2nd K2 (S/N 7869) and have run into a problem with the VCO
alignment. I'm getting a constant 8.37 V at R30  at 4.000 MHz.. I cannot
change it with the full range of L30. Correct type inductor is installed at
L30.  Dropping the VFO down to 3.500 doesn't change it either. I have gone
back through the archives and read just about every post concerning this
problem but nothing I have tried has made any difference. I have double
checked all correct parts placements and orientations, re-flowed all
connections in the quadrant of the board around the VCO section. T5 is
wound as per the manual (from the Toroid Guy) and installed correctly. I
have tried both spreading and compressing the turns on T5 with no change
either way.

Regarding the thermistor board,  I have 4.18 V on pin 5 of U6.

Test in the previous section were within specs:

4 MHz Oscillator Cal using CAL FCTR was 12099.61 and confirmed with an
external counter.
Range of the PLL reference oscillator: 12099.61 - 12086.01 = 13.59 kHz
VCO oscillator test: 8162.60 MHz

I'm about out of ideas at this point. What should I start checking next?

Thanks for any help!

73 de John, WB4GLJ
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