Hey Steve,
I've been using the 265' OCF Carolina Windom with a 22' vertical
radiator at 80' and it has been a good antenna on 160, 80 and 40...less
so on 20M up. The more poorly defined pattern which people point to as
a limitation of these OCFs is the very thing which makes it a good
antenna for these bands when you can only have one. I perceive fewer
directional nulls than I did with a 135' center-fed dipole in the same
place at the same height. I've placed very well in several 160M
contests using it for a transmit antenna and beverages for receive, and
heck even have over 100 countries on 10M with it, not that I consider it
a great antenna on 10M...it's pattern on 10M looks like a porcupine!
There are a few issues to keep in mind using an OCF:
I am using a Radioworks Carolina Windom OCF and it does have power
limitations. It can suffer from gradually rising SWR on CW at 500W at
certain frequencies which stress out the 9:1 transformer and CM choke at
the feedpoint even though it is rated for 1.5KW in this mode. It is
only rated for 100-200W in RTTY or digital modes, which is usually
adequate, but if one wishes to use higher power in these modes I suggest
they look for a more robust OCF.
For sure one needs a good ATU when using one of these antennas, I am
using the Elecraft KAT-500 which has always found a match on all bands
160-6M with this antenna.
Given the inherently unbalanced nature of an OCF and a Carolina Windom
in particular with it's vertical radiator, you MUST have several good CM
chokes on the feedline to isolate that radiator from the feedline. I
find the one supplied with the Radioworks 160M to be inadequate, and
have used K9YC's designs with two stacked 2.4" mix31 cores at the
feedpoint and at the house entrance in addition to the one supplied.
This has stabilized the SWR at higher powers somewhat, and my
house/wifewakey alarm now behaves itself when I'm doing 160M contests.
Sure there are better antennas, but considering how inexpensive/simple
the antenna and install is I think it is a good value.
Just my 2¢ worth...
Howie - WA4PSC
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