[SOLVED] Why use a Boonton 34A Resonant Line?

[chiques]

If I wanted to measure ESR of a capacitor at lets say 130MHz, I would need at least 0.57m resonant line.

Why not just use a high quality coax cable versus the Boonton 34A?

 

[krp]

Because the 34A has very high Q.

This should explain it;

https://sites.google.com/site/markwingalls/resonant-lines

 

[chiques]

Because the 34A has very high Q.

This should explain it;

https://sites.google.com/site/markwingalls/resonant-lines

I see now. So because this is typically used to measure "High-Q" devices, the component itself might out perform typical measuring equipment (such as an HP 4278A Cap meter) used in industry. Hence, a VERY HIGH Q resonant line is needed.

 

[Mark W. Ingalls]

krp,

Thanks for the boost. :smile: But I think there is more to say about chiques question, "Why use a Boonton 34A Resonant Line?"

There is nothing magical about the technique, and thus you can make your own high-Q resonant line. you don't need to use that old thing.

We have even had past success using loosely coupled microstrip lines. So let your imagination loose and live a little!

Mark

 

[krp]

OK on the "boost"; I found your articles very informative and I'm considering making a line as I have machining capability.

I've been idly thinking about using a helical-resonator structure; it may not have as high a Q as the line but it would be much smaller.

There is certainly lots more to say on this subject but my usual response to a question is to point the questioner to a source or sources that will allow him/her to find the answer.

Chiques; here is a good basic paper on Q measurement; it addresses lumped components, not the 34A, but it's a very good paper.

**broken link removed**

 

[Mark W. Ingalls]

YES! A helical resonator is a very viable choice, especially for low frequencies. (Basically, you want to avoid a magnetic component that radiates power.) You can use soft copper tube inside a cardboard "sonotube" lined with copper foil, even! Computation of DUT parameters might get a little interesting, but i think it had been done in the distant past...

 

[chiques]

Thanks for the insight!