[Hammarlund] SP-600 Electronic Dial

[Kenneth G. Gordon]

Miles:

I have used one I bought several years ago with several tube-type receivers 
and transceivers: the coupling method must be very carefully worked out, 
depending on the rig, and so far it has been different for each one.

Coupling to a metal sleeve over the oscillator tube has worked, but I don't 
like that method any better than you do. I view it as a kludge also.

Mine has even worked with a receiver with a regenerative detector (RAL-7), 
but only on CW so far.

The main thing I don't like about mine (can't remember the name right now) 
is that the 10 MHz crystal oscillator in it is so loud that it pretty much wipes 
out 10Mhz WWV, and there is no way to "tweak" that oscillator to zero-beat 
with WWV. Although it is off only by a few parts of one Hertz, it is annoying.

Nonetheless, the unit does make it possible to tune the various rigs to within 
10Hz, and I like that.

It is also pretty informative to watch the HF oscillator drift back and forth a 
few Hz. None of those I have used it with are what I would call perfectly 
stable, although some are far better than others.

Ken W7EKB