"Cecil Moore" wrote

Wouldn't the resonant circulating currents be at their
highest magnitudes at the parallel resonant point and
therefore the I^2*R losses in the coil be greater at
that frequency than on either side of self-resonance?
(I explained that avoiding self resonance is only a
personal preference.)
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Hi Cec,

The exceedingly small power loss in the choke depends on the impedance
of the power source which is driving it. It is a question of
non-conjugate mis-matching. But at self-resonance, and indeed
anywhere else, you can forget all about power loss. Especially as no
ferrite material is involved.

If you have bothered to check your "rule-of-thumb" and
"turns-per-metre-of-wavelength" against program SELFRES3, then,
provided results are in the same ball-park, all will be more than
satisfactory. SELFRES3 is itself only approximate. The choke's
self-resonant frequency is somewhat indeterminate as soon as anything
is connected to it.

A hank of a bunched number of turns is quite good enough as a coaxial
choke. It is only necessary to know the number of turns and the
diameter. Construction neatness helps with estimating the number of
turns but has hardly any effect on performance.

Coaxial chokes are a relatively unimportant circuit component.
Exactly what they are supposed to do is aways doubtful unless they are
used as baluns. I wonder why I am spending so much time discussing
the subject. Praps it's because I have nothing better to do.
smiley
----
Reg.