[Hammarlund] SP-600 Electronic Dial

[k2cby]

Has anybody tried to couple a digital counter to an SP-600 to make a digital
dial?

I've tried a couple of methods and none seems to work very well.

I have had passable results on the lower three bands (below 7 MHz) by
tapping off the feed 
from the HFO to the crystal oscillator switch through a 50 pF capacitor,
although the 
HFO signal is full of harmonics.

If I try this on the bands above 7MHz the HFO gets pulled to far off
frequency (even with the 
coupling reduced to 10 pF) I can't even align the receiver. (The trimmer is
too small.) The only 
solution I've found is to wind a multi-turn coil around the 6C4 HFO tube.
The signal is strong 
and the waveform looks real good, but it's quite a kluge.

 

Miles B. Anderson, K2CBY
16 Round Pond Lane
Sag Harbor, NY 11963
Tel.: (631) 725-4400

Fax.: (631) 725-2223
e-mail: k2cby at optonline.net