Topband: Elementary Inverted L questions

[Jim Brown]

On 3/25/2021 8:07 AM, N4ZR wrote:
> My feedpoint arrangement has 17 turns of RG-400 as a common mode choke, 
> with the radial field connected to the RG-400 shield at the antenna end.

Hi Pete,

I hope those 17 turns are wound around a #31 Fair-Rite core.

 > I connected the radial field (8 X 70-foot radials on the ground) and
 > that's when I saw the 1977 KHz resonance (X crossing zero).

The radials are part of the antenna -- that's why you had to connect 
them to see resonance, and it's probably why resonance is higher than 
predicted by the length of the L part of the antenna.

Resonance of an antenna like this doesn't make it work better, but it 
can make the power amp able to put power into the feedline, and it can 
reduce feedline losses. But loss in big coax (RG8/213) is pretty low on 
160M, so unless the feedline is pretty long (> 150 ft) SWR < 3:1 doesn't 
matter as long as the amp is happy.

73, Jim K9YC