Variable vacuum capacitors

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Variable vacuum capacitors

Postby FatSam » Wed Dec 30, 2015 10:30 pm

Image
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Could anyone tell me anything about these? I have eight of them, three have 7,500 volts on them and five have 15,000 volts on them. Also what are they worth?
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Re: Variable vacuum capacitors

Postby FatSam » Wed Dec 30, 2015 10:34 pm

Also have various brackets and clamps with them.
Image
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Re: Variable vacuum capacitors

Postby JOHN IN YORK » Thu Dec 31, 2015 2:07 am

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Re: Variable vacuum capacitors

Postby FatSam » Thu Dec 31, 2015 8:13 am

Thanks John, Very informative.
Next question, is there any way of testing them?
As I would rather advertise them as tested and fully functional.
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Re: Variable vacuum capacitors

Postby JOHN IN YORK » Sat Jan 02, 2016 2:24 am

Regarding testing of the capacitors.
As I do not know what equipment you have,I suggest that you have a look around on the internet.
But these might give you an idea of what is involved.

https://www.youtube.com/watch?v=A8oo64ZwPZw

http://www.jenningstech.com/technotes/testproc.shtml

Regards,John.
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Re: Variable vacuum capacitors

Postby m0lsx » Sat Jan 02, 2016 11:07 am

First do you have any details of these?? As you are going to need to know what test voltage to apply.
Also given the high charges these can hold make sure you first safely discharge the capacitor & then check for shorts using a multimeter before applying any voltage. Then test using a low current (amperage) & slowly increasing the voltage, but I think you only load it to a percentage of the maximum peak voltage, but once there you hold it for a period.
What you are looking for is arcing.
If arcing happens I seem to remember that it is possible to repeat the above several times. That is discharge & voltage test, as that can improve things & I believe sometimes with the correct kit it is also possible to revive an arcing tube, even if several cycles of test fails.
The above is from memory. I have never seen it done, but I am sure I read about this recently in relation to maintenance of a broadcast transmitter.
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Re: Variable vacuum capacitors

Postby m0lsx » Sat Jan 02, 2016 11:20 am

OK..I have just seen the photo's one has 7,500 volts on it the other 15,000 volts.
Even testing at 50% load would require a minimum 3,750 volts...
I guess a little beyond most of us.
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