Reg Edwards wrote:

"Roger Adam" wrote -

I don't see any mention of a fixed or variable capacitor. I take it that
there is one fitted!



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

Neither is there any mention of frequency. Where is the antenna analyser
connected? What parameters are being measured. How long is the feedline,
etc. ?

The frequency I chose for the *coupling* loop size was around 7 mhz in
the 40 meter band. I chose this because of the wide variation in loop
sizes called for by the program.

the antenna overall is designed to hit 75 meters, and at the other end,
17 meters. But 40 meters is the mainstay of this antenna.

The analyzer is connected to a piece of coax that is connected to the
coupling loop, which is a Faraday loop.

The feedline for the testing is around 5 feet of 50 ohm cable. I don't
doubt that my proximity to the antenna might have some effect, but I
don't expect it to be that extreme.



Does the antenna work when connected to a transmitter or receiver? If it
doesn't what are the symptoms?

Haven't connected it yet. I wanted to see if I was in the ballpark.
Initial tests suggested I probably aren't.


A magloop has an extremely high Q and narrow bandwidth. Behaviour
approaches that of a quartz crytal. If you don't get the expected
measurement results then the most likely reason is the limited capabilty of
the analyser. A precision, scientific-grade instrument is needed.

Now I am really perplexed! If I need an instrument such as you
describe, how will I ever get this thing to tune with my lowly IC-745?
It certainly isn't a scientific instrument. What I used to test the loop
was a MFJ-259 analyzer. Not "lab grade", for sure, but not at the bottom
of the barrel either. It has worked competently for everything else I've
used it for.

- Mike KB3EIA -