[Hammarlund] SP-600 Electronic Dial

[Les Locklear]

Miles and Group,

I used one from Electronic Speciality Products : 
http://www.electronicspecialtyproducts.com/index.html

The John R. Leary SP-600 I have has an rca jack by the hf oscillator 
tube (6C4), it worked, but the readout was about 70 kc low on the SP-600 
dial, there was a capacitance problem, I never pulled the rf deck cover 
to try different caps to correct it. There are other methods to connect 
it, such as the tuning cap, but I didn't try those methods. I did have 
one of their other dials in place of where the clock goes on a HQ-180A 
and it worked superbly. YMMV

Les
----- Original Message ----- 
From: "k2cby" <k2cby at optonline.net>
To: <hammarlund at mailman.qth.net>
Sent: Thursday, February 24, 2011 1:07 PM
Subject: [Hammarlund] SP-600 Electronic Dial


> 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
>
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