OK so with a center fed dipole fed with coax we have a balanced antenna fed
with an unbalanced feed. A 1:1 common mode choke is suitable to be placed
at the antenna feed point.
Now, since the antenna radiates, and the coax will be in the near field,
thus the shield will have some amount of RF induced on the outside or
shield. Therefore one needs some form of Common Mode Choke at the radio.
If one chooses to use only one Common Mode Choke or Line Isolator, best
first placed at the radio.
73
Bob, K4TAX
----- Original Message -----
From: <k4elo@fastmail.fm>
To: <tentec@contesting.com>
Sent: Sunday, June 01, 2014 11:42 AM
Subject: Re: [TenTec] Trading radios
Disagree Bob. Put the choke at the feedpoint of the antenna or your
coax will be radiating rf all the way down to the rig. If you can't
move the antenna, this is the most effective rfi fix.
73
Wayne
K4ELO
For starters, as to RFI issues, yes antenna to radio spacing, increasing
same, will usually improve the issue. Be sure all equipment is each
bonded to a common point such as the PS ground. Omit the external
ground but keep 3rd pin ground intact. Use a common mode choke on the
output of the radio.
73
Bob K4TAX
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