RadioBanter - View Single Post

March 12th 06, 05:33 PM posted to rec.radio.amateur.antenna

wrote:
John Popelish wrote:

Thank you for posting the test results. But I see no information that
would allow me to reproduce it. What test equipment and what
measurement set-up was used to produce these results?

I used a HP8753C network analyzer with small current transformers
similar to those used in directional couplers.

I calibrated using normal proceedures, and verified calibration by
inserting known transmission lines. For example when I substituted a
very short jumper, time delay was a few picoseconds. When I connected a
10 foot RG-8X jumper, time delay was about 13.5 nS.

For my phase angle measurements I used a dual channel HP vector
voltmeter with a HP generator, and similar current transformers when
measuring current.

I suppose most people would want to use a scope, but it would not be
near the accuracy of a dual channel vector voltmeter or especially a
vector network analyzer.

I have regular test fixture built on blank PC boards, since I do this
stuff every week for work. It does not "fit" a large coil well, so I
had to support the coil on two tall blocks of styrofoam and clip lead
to it.

I do have a large fixture that is a four foot PC board "box" with
various test jacks for connections to probes I use with larger
components, but my bench is to cluttered to fit it right now. In any
event a groundplane several inches away doesn't seem to bother things.
The only thing that moved when I moved the inductor close to the
fixture was the self-resonant frequency came down a few MHz. Time
delays did not change much unless I added an extra foot of clip lead,
then they increased about 1nS.

If it's useful, I guess I could add some more stuff. But probably
nothing extensive until after Dayton.
(snip)

Thanks much. This helps me to visualize your method in a much more
complete way. I think a photo of the test apparatus would make a fine
addition to your web page documenting this result. I am especially
interested on how all this stuff was arrayed in space during the test.