[Elecraft] K2 - VCO-Test (Alignment an d Test, Part II)

[Masleid, Michael A.]

Hello David,

>When I measure the voltage between junction of d21-d22 and ground I get =
7.7
>volts the frequency rises up to 8.9 MHz - so strange!

(I don't know if this matters - normally the frequency probe is not =
connected
 for this part of the VCO tests.)

I can't figure between Q18 having too much feedback - value of C68 too =
high.
Or else not enough gain, perhaps, Q18 bad.  Poking around places that =
are
carrying the VFO signal could add feedback, or load down the circuit and
reduce feedback, or do both at the same time.

Put a 2.2 kOhm resistor across terminal 1 and 2 of T5 as a test.
This should drop the Q to 50, loading it down real good.  If that
makes things better, then C68 must be too much feedback, too
large a value.  Perhaps reduce C68 to 4.7 or 5 pF as in the
pre-160 meter kits.

Or the other possibility:

Put 5 pF in parallel with C68 as a test.  This should increase feed =
back.
If that makes things better, then C68 is not enough feedback,
so perhaps Q18 is sick.

73 de Michael AB9GV