We were speaking about using this transmission line at HF frequencies.
30 MHz is the highest frequency but for the vast majority of operations (on
the air time), you could even say 21 MHz is the upper frequency limit.
The study in that paper was showing 50 MHz and above.
It appeared to get rapidly worse as the frequency rose.
Can we not assume that it gets rapidly better at lower frequencies?
If so, then Joel's test results could be accurate.
If a non engineer measures losses on a line, then drags it in the mud and
measures again, and gets trivial differences in the results, shall we
discard his results just because he's not an engineer?
L.B. Cebik? As I recall he was not an HF engineer, yet we (or I) hold his
writings to be some of the best in existence.
To be fair to Joel, we should at least read the article, see what he
measured and how he measured and then criticize his results if something is
foul. I don't think it's fair to criticize the paper based on what kind of
Engineer wrote it.
It wasn't really rocket science he was performing.
It was simple tests that any good ham could perform.
We just never took the time to do it.
Unfortunately when I moved from the states back to Germany, I threw out all
of my magazines so I no longer have the article. Maybe someone else here
does and can recap what Joel reported. THEN we can beat it to death.
73
Rick
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Steve Hunt
Sent: Thursday, January 26, 2012 8:18 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Re. [Ten Tec] Grounds and balanced fed verticals
The article by Wes Stewart that I referenced earlier:
http://www.scribd.com/doc/7132619/Ladder-Line
was published in the ARRL Antenna Compendium Volume 6. It shows measured
losses for various commercial ladderlines when wet and dry. For example,
the loss of Wireman 551 increased from 0.33dB/100ft @ 50MHz to
5.8dB/100ft @ 50MHz; by contrast the loss of a home-made open-wire line
comprising #16 wire spaced 0.75" was 0.3dB and did not change when wet.
By the way, ARRL figures in the Antenna Book, and in their TLW software,
for ladderline grossly under-estimate the loss. If you do the basic RF
resistance calculations you'll get losses almost exactly double the
values they quote; I can't help think that whoever did those
calculations might have forgotten there are two wires :)
Steve G3TXQ
On 26/01/2012 18:20, Jim Brown wrote:
> On 1/25/2012 10:54 PM, Rick - DJ0IP / NJ0IP wrote:
>> He found when the window-line gets wet from rain or snow, its impedance
>> changes a little and you have to re-tune your matchbox - but the
efficiency
>> is still the same.
> In one of the excellent ARRL Antenna Compendiums, Frank Witt published
> the result of his research (including careful measurements) of loss in
> open wire line and window line when it gets wet. Frank is a real
> engineer. W1ZR is not -- he is a writer, and his writing in QST is full
> of technical errors.
>
> 73, Jim K9YC
> _______________________________________________
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>
>
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