In article ,
Fred W4JLE wrote:

Again, what I am looking for is a simple chart that says for a 10, 15, and
20 meter beam a solenoid of 8 turns on a 4 1/2" pvc coil form will provide
the following impedances ...

http://www.bcdxc.org/balun_information.htm#Ed,%20WA2SRQ has some of
that sort of information, for a few specific combinations of turns,
diameter, and winding style.

Also most people will tell you that just looping the coils together will
cause problems because of capacitance. I don't see that as a bad thing.
Again I need to see data to confirm or discount my assumptions.

What I have heard is that scramble-winding the turns tends to create a
higher distributed capacitance, and lowers the frequency at which the
balun exhibits self-resonance.

This appears to be born out by the table in the URL I gave above.
Compare the "8 turns, 6-5/8" columns for single-layer and bunched
windings. The single-layer coil has its peak impedance at 12 MHz.
The bunched-turn coil peaks somewhere between 6 and 7 MHz (highest
displayed impedance is at 6 but the phase is still very positive, so
I'm inferring a higher-impedance peak between 6 and 7 MHz).

The impedance of the bunched-turn coil seems to drop faster, on either
side of resonance, than that of the solenoid-would coil.

This suggests to me that the bunched-turn coil, measured and trimmed
carefully, might be a convenient choice for a low-HF monoband
antenna's choke, since it'd need fewer turns of coax to achieve a high
choking impedance. The solenoid-wound coil appears to have a somewhat
broader effective frequency range, and thus might be a better choice
for a 10/15/20 tribander.

--
Dave Platt AE6EO
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