Dear JA, LF group,
The basic idea of connecting the variometer coils in parallel seems to be
sound, but I made an error in the calculation. More careful calculation
shows that, for the parallel connection:
L = (L1L2 - M^2)/(L1+L2-2M),
Where L1, L2 are the inductances of the two coils individually and M is the
mutual inductance between them. In this case, L1 = 3.38mH, L2 = 1.33mH, M is
between -0.95mH and +0.95mH, making the adjustment range for JA's variometer
with the coils in parallel 0.54mH - 1.28mH, which is still OK. Calculating
inductances of coils is often not very precise, so it would certainly be a
good idea to check the inductance as Peter describes, to make sure you are
in the right range.
Cheers, Jim Moritz
73 de M0BMU
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of James Moritz
Sent: 05 July 2006 09:24
To: [email protected]
Subject: LF: Re: Antenna Tuning
Dear JA, LF Group
...
Connecting outer and inner coils in parallel instead of in series will give
an inductance range of 0.32 - 1.49mH, which would be good. I am not quite
sure if this is correct, so will have to check.
Cheers, Jim Moritz
73 de M0BMU
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