[Milsurplus] not a capacitor

[J. Forster]

Hmmmm....

There is no doubt that ceramics can have a high voltage coefficient of
capacitance. This is due to the piezoelectric properties of the ceramic.
It's easy to measure and demonstrate at DC and low frequencies.

However, I am unconvinced that this effect continues to RF frequencies.

It is certainly possible that, if you measured the impedance v. frequency
of the capacitor, there could be a peak in the MHz region. The thing could
well act as an electro-mechanical resonator.

As to a harmonic generator at RF, I am doubtful.

FWIW,

-John

==============






> At several of my jobs we have had troubles with performing AC hi-pot
> tests on equipment using ceramic disc capacitors as line to ground
> filters.
> They often have a horrible voltage coefficient of capacitance. At power
> frequencies the resulting high peak current either trips the current limit
> on the tester or sets up resonance effects with power limited (neon sign
> type) HV transformers to produce ugly waveforms and destructive voltage
> peaks. They pass a DC test with no problems at full rated voltage.
>  
> They should make nifty harmonic generators at RF.
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