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Old March 11th 06, 05:30 PM posted to rec.radio.amateur.antenna
K7ITM
 
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Default Current through coils

I think Reg's estimate of both inductance and first self-resonance (or
is that self-anti-resonance?? ;-) are a bit high. Methods I trust all
predict about 97uH and self-resonance at very close to 8MHz, for a coil
wound with 16AWG to a 2-inch inner diameter. (Inductance would be a
bit lower if that's the wire center-to-center diameter.) Winding and
measuring one to see which estimate is closer is left as an exercise
for the reader, but I wouldn't trust either Reg's or my estimates on
this for building an inductance standard (and besides, I'd build such a
standard with a lower L/D).

A transmission line model shows 13.5 electrical degrees of line at
1.9MHz, at about 6140 ohms. You should probably look up an article by
John Mezak that appeared in "RF Design" some years ago before you to
applying that info willy-nilly, but I don't really expect you will.
Have fun.


Cecil Moore wrote:
Reg Edwards wrote:
A 100 turn coil, 10 inches long, 2 inches in diameter, has an
inductance of 102 microhenrys, a Q of aproximately 380 at F = 1.9 MHz,
and the self-resonant frequency is 12.0 MHz. Its radiation resistance
at 1.9 MHz is negligible.


Good stuff Reg. Modeling it as a transmission line, what would
be its Z0 and VF?
--
73, Cecil http://www.qsl.net/w5dxp


 
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