I assume the article is referring to the coil dimensions in the _ARRL
Handbook_. Each coil works best over about three bands. I highly
recommend both the _ARRL Handbook_ and the _ARRL Antenna Book_. Not all
the world's knowledge is on line yet.

If you have an antenna analyzer, you can measure the impedances of your
experimental chokes. Twist the center conductor and shield together at
both ends of the coax. Connect one end to the center conductor of the
analyzer, and the other to the analyzer body. Adjust the coil for the
highest impedance at the frequency or frequencies of interest.

Roy Lewallen, W7EL

Jack Twilley wrote:
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It's a good weekend for home improvement, so I thought I'd tune my
antennas and replace my coax with longer runs to suit where I'd like
to place my station. I figured now was a good time to build in an RF
choke in an attempt to remove interference and hopefully be able to
receive HF, but there are no online resources with formulas or
anything. I was hoping for something like the innumerable dipole
calculators out there -- something where I could input a frequency and
a diameter, then select a type of coax, and hit a button to find out
how many turns.

Most online references are very vague, so I'm just going to
experiment. I was hoping, though, that someone could direct me to a
useful reference. I have an PDF of an old QST article which says that
W7EL has a table in the Antenna Handbook. A friend of mine has a copy
of the Antenna Handbook, but she may have lost it in the move.

Any suggestions? Right now, I'm going to experiment with different
values and see what I can discover, but it can't hurt to hear about
what others have done.

Jack.
- --
Jack Twilley
jmt at twilley dot org
http colon slash slash www dot twilley dot org slash tilde jmt slash
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