Re: How to repair a fine coarse tuning poti ?
Systron Donner 6057 Counter. VFO tuning potentiometer.
It is a dual 1k for the fine tuning and a single 16 turn 100k for the main tuning, all balanced across the +15v and -15v lines.
Your chances of finding a suitable complete replacement are nil I am afraid. And a specific replacement part from the makers would cost more than you paid for your unit or perhaps it's original cost in 1973.
But a standard 10 turn 100k wirewound pot would be possible, or perhaps better as it will be smoother, an end adjust rectangular cermet pot with panel mounting and some experimenting to fit a knob would work very well.
I have had a look at my unit, and there is not a lot of space, so the cermet pot might be a better alternative.
But I tend to agree with David factory and the fault is more likely elsewhere. Put your meter of the lead to pin 2 on the oscillator board A2 and see if the voltage changes up to +-15 v.
The manual is now scanned and will be on its way to you shortly.
wme_bill
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