A tuning cap question - Printable Version
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A tuning cap question - morzh - 02-14-2014
What keeps (if anything) the rotor vanes connecting bar from connecting to stator when the vanes are fully in (or out)?
Or are they supposed to touch and the dial limit stops are what is intended to keep them from touching?
My oscillator group touches when fully closed.
I could put a piece of Kapton on the stator bar....but wanted to know.
RE: A tuning cap question - Chuck Schwark - 02-14-2014
Stator and rotor plates never touch from one end of rotation to the other.
Otherwise, you have a shorted component, not a capacitor.
On older var caps you had to carefully make sure bent plates were straightened. New types have a "bar/bridge" of insulating material like phenolic holding the "long" ends of the rotor plates in place.
Chuck
RE: A tuning cap question - morzh - 02-14-2014
OK, when I aligned the dial so the local station plays where it should (1140) the stop kept the rotor from touching....though I did think before that the cap should not touch anyway (and I always wondered why).
RE: A tuning cap question - morzh - 02-14-2014
Did not see the response:
Chuck, the plates are not bent and the gaps are quite large. It is not vane touching vane, I know it is that bar bridge that touches when fully close and it is aluminum. So what you saying, it should not touch?
RE: A tuning cap question - Chuck Schwark - 02-14-2014
If the mechanics of the dial mechanism are such that the var cap over-travels, then I would insulate that alum bridge plate. Couple layers of electrical tape cut to match the bridge's rectangular shape.
Chuck
RE: A tuning cap question - morzh - 02-14-2014
Yes that is where I thought of Kapton above....I have a roll at work.
But the mechanics of the dial when aligned propely, as I found out, keep the cap from over-travelling. So it is OK now even without the Kapton. I just never saw the cap by itself touching before. Even with aluminum bar bridges.....maybe I did not really tried.
thanks Chuck.
RE: A tuning cap question - Chuck Schwark - 02-14-2014
No problem. :-)
….and it's Friday…..
Chuck
RE: A tuning cap question - morzh - 02-14-2014
Oh yeah....!