From: "Mark S. Rzeszotarski, Ph.D."
Date: Wed, 20 Dec 2000 15:23:21 -0500
Subject: Re: [TSSP] Coils at high elevation
Hello All:
At 07:27 PM 12/20/2000 +0000, you wrote:
>Yes. f1,f3 and f5 on suspended coils of around h/d = 4 and
>h/d = 1 would do nicely.
>
>> > [+] Mark's coil, which exhibits a higher discrepancy
>> > in f1, has
>> > a Cint contribution of only 17%, since it has h/d=6
>> > which gives a
>> > smaller Cint to begin with. This leads me to believe
>> > that Cint is
>> > not to blame.
>
>> Becouse of high h/d ratio that is my thinking too.
>
>I hope so - Cint is the hardest to fix! Has anyone heard
>from Mark lately?
>
>Regards,
>--
>Paul Nicholson,
I have been out of town and am still catching up on posts. I may
actually have some time for coiling measurements next week. Can you outline
exactly what you want? I can wind appropriate H/D if needed. I have most
even wire sizes from 16 to 28 AWG and a few smaller than that.
The constraints at my end are equipment based: my vector impedance
meter works from 400 kHz to 10 MHz so I have to work with relatively small
coils with that unit (Fres > 400 kHz). It is useful for measuring odd
harmonic Zin. I can make a series of measurements around these values as
well, but not at the even harmonics, where the meter will not stabilize due
to voltage peaks at the drive point. Normally, I connect the meter ground
to my good RF ground and then drive the base of the coil with the vector
impedance meter active element. I could drive it from the top with the base
grounded if you thinbk anything can be learned from it. I can also take
some measurements versus height above ground outside if you like (if the
snow lets up).
Alternatively, I can use an inductive feed with low coupling to
energize the coil and observe it using a plane antenna a la Terry Fritz. In
this case I can measure resonant frequencies accurately, but not Zin.
Let me knowwhat might help sort things out.
Regards,
Mark S. Rzeszotarski, Ph.D., MetroHealth Medical Center,Radiology
Department, Cleveland OH 44109-1998
Maintainer Paul Nicholson, paul@abelian.demon.co.uk.