[Elecraft] K1 1408 passed the smoke test, but the VFO will not change frequency

[Jess Gypin]

Hi all,

I am at the point where I need to set the upper and lower frequencies of the
VFO and it will not change frequency. The oscillator shows 3093 hz. The VFO
will not change frequency. I have traced the 10 turn pot to P1 of RP-2 and
verified the xtals on the filter board. The problem appears to be that the
voltage at D3 is not changing. With the change in resistance of the tuning
pot, the voltage at P2 of RP-2 and at the cathode of D3 never changes from
5.91 volts unless I hit the clockwise stop and the pot resistance almost
goes to 0, then the VFO will jump and change frequency. Also the voltage at
the cathode of D4 never goes below 2.91 but that is to be expected if the
voltage at the first varacter is not changing.

I ohmed out the varacters for D3 and D4, and they measure about 600 ohms one
way and infinite the other. I would assume that since I am getting a voltage
change with the pot at the stop and the frequency changing, that the VFO
works, but the voltage at the varacters in not changing with the change in
resistance at the 10 turn pot.

This is driving me nuts. I had hoped to have this finished in time for my
trip to Boston on Monday to pass the nights in the hotel. Any clues or
insights would be greatly appreciated.

Jess AE0CW <><