[Antennas] Carolina Windom

Sat Jul 16 14:06:12 EDT 2022

[This is a resend because the list appears to have silently dropped my
message, perhaps because the earlier copy was signed with OpenPGP.]
"Steve H" <teknoskillz at comcast.net> writes:
> Was given one of these a while back, (I think its the jr) and it is
> basically an 80m OCF dipole with about 25 feet of 300 ohm 18 ga window
> line at its feedpoint , terminating with a W2AU 4 to 1 balun. I ran
> some 50 ohm coax on the other side of the balun and someone had said
> that the balun was only 300w rated. Its up in a tree almost 40 feet.
> As per a sugguestion, to make the dipole a better radiator I removed
> the balun and spliced in more window line, it turned out to be about
> 50 feet 20 ga, which was all I could dig up.

I have a "Carolina Windom 80", from:
 http://www.radioworks.com/
 http://www.radioworks.com/ccw80.html
Despite the web site having a buy button, I do not have the impression
that they are still in business (an email question a few years ago was
not answered, and note the front page). If you have a radioworks
product, see:
 http://www.radioworks.com/2006%20product%20manual.pdf
On mine, there is a 4:1 balun at the 1/3 point of the OCFD, and then
coax to a balun. It is indeed part of the design that the 22' vertical
section radiates, and I acknowledge that this might be bad or good
depending on how your local noise is and where you want radiation any
given minute.
Yours seems to not have a balun at the OCFD 1/3 point, and to have a 4:1
balun (which perhaps is a current balun that will choke off current in
the coax shield, and perhaps not. By extending the 300 ohm line, you
have very likely created a radiating feedline all the way back to the
shack.
I don't follow the suggestion to use balanced line all the way in the
first place; there are three separate issues:
 actual radiation by the dipole element after matching
 matching issues
 vertical element and feedline radiation
I would suggest getting something that can measure current on the
outside of the feedline; I've seen various articles about how to do this
and don't remember the details, but a sense transformer seems plausible,
or near-field probes. You can also add a common-mode choke and see how
that changes things; if it does, you had current without it. In
particular, see if noise is decreased.
73 de n1dam