Higher Capacitance

[thadde]

Hello everybody

I am working with the AIM 4170. When I measure a single cap I discover, that the value of the cap is increasing, is getting higher with higher frq. I see that there is a resonant frq. There must be a hidden inductance. At low frq. it seems that the measurement is true or mostly correct (compared with the measurement with the L-C meter.

What does the AIM 4170 calculate for the changing value of a cap?

If someone knows more about it, I would like to hear from you.

Thadde HB9DNB Lucerne Switzerland EU [e-mail]

[kc0ws]

All capacitors have some inductance in their leads. The longer the leads, the more the inductance. That inductance series-resonates with the capacitor at some frequency. Below that frequency, the equivalent capacitance goes down, as the inductive reactance is cancelling part of the capacative reactance, and the cancellation increases with frequency. Less capacative reactance looks like a bigger capacitor.

Above the series resonant frequency, the capacitor becomes inductive, and looks like an inductor.

What kind of capacitor were you measuring, and at what frequency did you plan to use it?

Most parts have parasitic charactaristics at RF (especially VHF) and are quite willing to look like something other than what they are labeled.

Ted

[thadde]

Hello OM Ted

Mni tnx for ur kind answer. Is it possible to send a direct message via E-mail adress? So it is easyer to send information, written by hand. I dont do a inproprer use of your E-mail adress!!!! If you agree I would be happy, but I understand your oppinion, if you dont want.
Have a good time, with very 73, till later Thadde HB9DNB Switzerland Lucerne [e-mail]