Cecil Moore wrote in message ...
Dr. Slick wrote:
So for most of the dipole based antennas (including Yagis), you
can use 6 turns of 4" diameter coils in the coax, to make an inductive
loop that is supposed to prevent current from moving down the outer
braid (non-radiating).

6 turns is probably not enough inductance to do much choking on 160m
or 80m.

If the dipole is non-resonant, 6 turns of coax may have very little
effect on any HF frequency.


What's up Cecil?

ok, you may be right about HF, but for VHF (30-300 MHz), 6 turns
in the coax is enough.

So have you made an inductive coil in coax for HF? If so, how
many turns did you need, and what was the diameter of the turns?

I may need to do this for an AM station one day, but maybe not
because most AM antennas are some sort of end-fed random length
wire with a tuner, where the wire length is greater than 1/4 wavelength.
In other words, i haven't seen any dipole antennas for broadcast band
AM....it would be too long!


Slick

Dr. Slick wrote:
So have you made an inductive coil in coax for HF? If so, how
many turns did you need, and what was the diameter of the turns?

I once made one out of a 2-liter pop bottle about 1/3 full
of turns of RG-8X. It worked pretty well on 40m, my favorite
band, but a thunderstorm destroyed it. I have no idea what
the choking impedance was.
--
73, Cecil http://www.qsl.net/w5dxp



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