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 Capacitor testers
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 Return to top of page · Post #: 1 · Written at 10:38:23 PM on 19 August 2017.
Dalpets's avatar
 Location: Adelaide, SA
 Member since 17 August 2017
 Member #: 2154
 Postcount: 10

What reasonably priced modern capacitor testers are capable of test measurements with vintage high voltage radio equipment?

At present I have only a Der EE DE-5000 which I think might not be capable of such measurement.

Thanks for any recommendations.


 
 Return to top of page · Post #: 2 · Written at 12:01:00 AM on 20 August 2017.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 2747

Be careful: Capacitors require two tests. Apparently there is a really good capacitance & inductance meter (with no instructions) for under &10 out of China. Someone was going to send me data on it?

One of the issues with some meters is in the area of pF: No can do even if they claim they can. The voltage rating does not play a large part in measuring the capacity of the capacitors.

Non polarised capacitors in Valve radios can generally cop up to 500V in Filament rectifier sets, with heater valves. and then we have wax paper & oil filled caps. These can read good for capacity & still be useless. These suffer electrical leakage., in most cases these are just tossed as the probability of a good one, has very very long odds against.

The way I leakage test them (if I bother) is with a now superseded insulation tester I got from Altronics. This unlike the Tag & Test ones & others, has four ranges of voltage that gets you pretty close to the common "B" voltages used. The only info I have is that less than 50Meg for screen decoupling & 200Meg for coupling caps renders them unfit for purpose: Most times with Wax Paper types you are flat out getting one past 1Meg. I tested one this week (for a reason) and it was 0.7 Meg . 250VDC. Should be infinity. No longer in radio.

The Valve & circuit tester (VCT circa1938) uses a Neon tube in series with the cap. So simple: Blink as the cap charges & then the neon light extinguishes. If the cap leaks the intensity of the glow increases. These days if it glows you toss the cap.

Electrolytics are different. You do not use insulation testers the hand held meters will read their capacity, but operationally that does not tell you their condition either. They dry out & loose capacity, or they lose polarity (form) & can present as a short. They are meant to electrically leak, but there is a limit.

So do be aware of what you are being presented with & are trying to do. A lot of equipment is unsuitable for RF work & Valve radio.


 
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