Yes, I agree that true open wire line does not have that issue. However,
in as much as I have the feed-line from the antenna, standing off of the
tower some 18", entering through an eve vent, then through the attic
supported under the wood roof rafters, and dropping down through the
ceiling to my operating position, using true open wire line would be a
challenge. In my installation, I add 10 twists per 10 ft so as to
minimize any adjacent item causing unbalance plus minimize any wind
loading. With true open wire line, this would be a challenge.
I've used this system for more than 25 years with a great deal of
success and very little to zero issues. It is just ones understanding
the need for a slight adjustment of the ATU values to compensate for
weather changes. No different than frequency changes. The KPA500 or
the KAT in the radio handles any needed changes 100%. The currents in
each side of the line are balanced to 5% or better and there is no
measurable common mode current.
I wish more hams understood this and they would likely have better
antenna systems, as opposed to some of the haywire crap I've see at some
QTH locations.
Thanks
73
Bob, K4TAX
On 12/28/2021 11:46 AM, Lyn Norstad wrote:
Bob -
Should you ever feel the need to replace your feedline, open wire line will
solve that problem.
73
Lyn, W0LEN
-----Original Message-----
From: elecraft-boun...@mailman.qth.net
[mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Bob McGraw
Sent: Monday, December 27, 2021 7:36 PM
To: elecraft@mailman.qth.net
Subject: [Elecraft] Output power being eaten
I doubt that ice on the antenna would have any effect in terms of
increased loss. However, I would expect the resonant frequency to
change and thus the need to adjust the tuner. If it is and ATU /
automated tuner, then perhaps a bit too low power may cause the SWR
bridge to read incorrectly.
I use a KAT500 and my TUNE power is 20 watts. This assures the ATU and
SWR circuits have adequate signal to perform the desired function. As
to the SPE 1.3K amp, as fussy as they are, I'm surprised it didn't trip
off line.
My experience with antenna's changing due to moisture is with my
balanced center fed wire which uses window line for the feed. It
accumulates moisture, frost, rain, snow, and ice. The change I do see
is due to the velocity change of the balanced feed. My measurements of
a couple of years back indicated the length of the line changed
electrically thus a velocity factor change. Any loss, wet or dry, under
matched conditions was not measurable over a length of 100 ft on 20M.
Therefore, I would expect the mis-matched loss to be about as the book
say. Again, either wet or dry.
73
Bob, K4TAX
On 12/27/2021 4:10 PM, elecraft-requ...@mailman.qth.net wrote:
Message: 21
Date: Mon, 27 Dec 2021 14:10:25 -0800
From: Fred Jensen<k6dg...@gmail.com>
To: Elecraft Reflector<elecraft@mailman.qth.net>
Subject: Re: [Elecraft] Output power being eaten
Message-ID:<8c012d97-f62d-b342-4ec3-20db2e8f5...@gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
I doubt that pogonip or even solid ice on your antenna would have major
effects [well, except for weight].? Ice forming from water directly from
the sky is a pretty good insulator.? We had a very large Log-Periodic on
the roof of the hangar at my first USAF assignment in the remote
northern interior of KL7.? Lots of ice fog creating rime ice on the
elements in the dead of winter, much of which was -35 C or below.? In
the so-called spring, solid ice would form on them, and there was
essentially no perceptible change in the antenna performance.? If your
ATU wasn't getting enough power to tune, it was probably "eating your
power" rather than the ice on the antenna.
At home, I have an HOA "WOOF" antenna [Wire On Organic Fence] at about 2
m AGL.? We've been having a series of snowstorms, the top of the fence,
including the wire, was encased in snow yesterday for the 40 m ECN, and
it worked as good as it ever does.
73 & HNY,
Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County
Bill Frantz wrote on 12/27/2021 11:48 AM:
I didn't have a good night in the K1USN Slow Speed Test. I started
more-or-less on time and tried to answer CQs. None of the stations I
tried
could hear me. My SPE 1.3K amp said I was putting out about a kilowatt,
although the antenna tuning on my normally low SWR 40M dipole needed
to be
redone. I was receiving many stations, at normal levels.
After a few minutes, I started searching for causes, since operators
calling CQ weren't hearing me and sending CQ again. Some of these
operators had worked other stations, so I knew their radios were
basically working. I tried maybe a half a dozen stations.
Finally, in desperation, I raised the tune power in my K3 exciter to 15W
and retuned the dipole yet again. Things started working and I managed to
check into the Elecraft 40M CW net via KD5ONS in OR at 0050z. With only 5
minutes in the contest left, I managed QSOs with W6SX and VE5MX.
Thanks to
both of them.
My current theory about what was happening is that ice on the antenna was
eating transmit power, although receive seemed normal. Does ice seem a
reasonable explanation? What else could be the cause? I'd love to come up
with a believable answer. Even more so, avoid the situation in the
future.
73 Bill AE6JV
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