[AMRadio] Tuning motors

[Donald Chester]

Dave,

If you simply can't find replacement motors anywhere, and your primary
interest is restoring the function without necessarily being historically
accurate, one possibility would be to use modern stepper motors. They are
available in wide range of torques,  and as I recall, the steps are
something like 1.9 degrees each, allowing very precise control of the shaft
position. You might even be able to configure the stepper motor so that it
could easily be replaced with a stock motor if one ever becomes available.

I have entertained the idea of using one to remotely control the big rotary
selector switch for my antenna tuners at the base of the tower. That would
solve the critical requirement to make sure the switch landed at TDC in each
position. The biggest "if" factor is lightning, since the things use solid
state devices in both the motor and the control unit, so I haven't made any
effort to start on that  project. I didn't have my remote tuning system up
and running more than a month before lightning wiped out the very rare and
expensive indicator meter I was using, but fortunately someone was kind
enough to send me a replacement. Now, I completely disconnect the line
running out to the tower whenever the unit is not in use.

Do a Google  search for "stepper motors" for more information on how they
work.

Don