[TowerTalk] FW: In Shack Tuner Vs. Remote Tuner for Multi-Band Antennas

[Jim Brown]

On 5/3/2014 6:49 AM, Jim Lux wrote:
> With coax, if you find that the shield is picking up RF current and 
> re-radiating, you can throw a choke on it to stop that. 

But ONLY if the SWR at the feedpoint is in the reasonable range (5:1 or 
better), and only if it is a serious choke (high choking Z). N6BV has 
shown (and I have verified his work) that in extreme cases -- for 
example, an 80M dipole loaded on 40M -- high power will very quickly fry 
a choke at the feedpoint.

Bottom line -- all band dipoles and OCF antennas are a very bad idea in 
today's world where RF trash is everywhere. I view them as an unnatural 
act. Yes, you can load a random dipole fed with high Z line and get it 
to accept power, but the pattern will vary widely with frequency (lots 
of nulls), and because you can't choke the feedline, it will pick up 
lots of noise.

There ain't no free lunch. Resonant antennas fed with coax rock. The 
others "roll."

73, Jim K9YC