[Elecraft] K2 #4028 VFO moving in "steps".

[James T. "Jim" Rogers]

	Alignment and Test Part II -VCO Test
	Unable to adjust L30 and achieve 6.0V at R30.
		Verified turns counts on T5 as 16T and 4T.
		Verified c72 in in circuit (measured K13 continuity pin 3 to pin 4).
		Verified L30 is correct component.

	Additional Information
		- Reference Osc range test was satisfactory, 16.59khz.
		- VCO frequency test was within the specified values of 8 to 10 MHz at
8923.66khz.
		- As L30 is adjusted voltage at R30 does change.
		- Low pass filter U6B shows 4.05 V on pins 5 and 6 and an output of 1.5V
on pin 7(max approx 2.7V).
		_ I set the voltage at R30 to 1.5V using L30 as a reference and tuned from
3.5MHz To 4.0MHZ. The voltage at R30 changed - from .3046V at displayed
3.500MHz to 1.499 at displayed 4.000MHZ, however I discovered it is moving
in "steps". This leads me to believe U5 (DAC LTC1451) is not doing its
thing. Pin 7 of the DAC reads 4.01 volts and never changes. Reheated SC0,
SCK, and DAC2CS joints at connector J8. Reheated pin connections at DAC
itself. Checked signal origins on controller board from MCU to associated
pins on P3 (ain't much can go wrong there, straight shot).

	Anyone got any ideas of where to look next? I have a few hours to get as
far as I can before panicing and e-mailing or calling Gary. Meanwhile I am
off to the local Radio Shack to see if I can find the pieces to build a
logic probe so I can really verify I am getting wiggles on some of these
lines.