On Wednesday, December 17, 2014 6:34:22 PM UTC-6, Ralph Mowery wrote:
I have a home buit version of the Carolina Windom. An off center fed
antenna about 120 feet long with a 4:1 voltage balun and from the feedpoint
it goes to an inline ferrite bead choke 20 feet from the feed point, then 80
feet of rg-8 to the shack.

The balun is suspose to be rated for 3 kw. It does have 2 cores in it.
By tests, I know if I run ssb at over 800 watts the balun will heat up and
change the swr.

I have noticed lately that running just 100 watts ssb on 80 meters the swr
seems to be going up to about 2:1 and the rig cuts the power back as
expected as I talk from a starting point of 1:1. That has hapened for the
last two mornings. I don't recall it doing that before. The antenna has
been up for several years. It is just over 1:1 when normal on the frequency
I most often operate on. Today in the afternoon when 80 meters was dead I
transmitted a carrier for about 5 minuits and let off to ID, then another
carrier for about 5 minuits and the swr did not change.

Any ideas why the swr went up for the last two mornings, but did not seem to
go up this afternoon ?


Hard to say really, but sounds sort of moisture related..
Maybe moisture freezing, and then melting, or wet moisture that
later dries out. Just a guess though..
If that balun warms up, it's adding a substantial amount of loss.
Not really related to your problem, but I hate to see perfectly useful
RF turn to heat. :|
Also kind of verifies my theory of the cause of the loss I saw when
using one of those antennas at a field day several years ago.
I had compared it to a regular coax fed dipole, and it was way
down from the dipole.
I always blamed the voltage balun it used, and your experience sort of
verifies that assumption.

wrote in message
...
Hard to say really, but sounds sort of moisture related..
Maybe moisture freezing, and then melting, or wet moisture that
later dries out. Just a guess though..
If that balun warms up, it's adding a substantial amount of loss.
Not really related to your problem, but I hate to see perfectly useful
RF turn to heat. :|
Also kind of verifies my theory of the cause of the loss I saw when
using one of those antennas at a field day several years ago.
I had compared it to a regular coax fed dipole, and it was way
down from the dipole.
I always blamed the voltage balun it used, and your experience sort of
verifies that assumption.


While some of the RF is converted to heat, I also have a 80 meter dipole at
the same height and at right angles to the OCF antenna. Switching back and
forth between them, the OCF is usually beter. In a few cases the plane 80
mete dipole without a blun will work beter on 80 meters.

Just a few months ago I hung an 18 and 24 MHz dipole about 6 inches bleow
the 80 meter dipole and fed off the same coax. Still the OCF is usually
beter.

The ends of both antennas are about 50 to 60 feet off the ground and not
suported in the middle or at the feed point.



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On Thursday, December 18, 2014 5:05:35 PM UTC-6, Ralph Mowery wrote:

While some of the RF is converted to heat, I also have a 80 meter dipole at
the same height and at right angles to the OCF antenna. Switching back and
forth between them, the OCF is usually beter. In a few cases the plane 80
mete dipole without a blun will work beter on 80 meters.

Just a few months ago I hung an 18 and 24 MHz dipole about 6 inches bleow
the 80 meter dipole and fed off the same coax. Still the OCF is usually
beter.

The ends of both antennas are about 50 to 60 feet off the ground and not
suported in the middle or at the feed point.

I was thinking in terms of 80m. I suppose it's possible the windom
could be better on some of the other bands. IE: a 80 dipole is not
going to be too good on 40m unless you use a low loss method of feeding
the high Z antenna.