I totally agree. Your measurements are "real world" and correct!
I've used ladder line of various types for years and very successfully.
Even at one time I used it, actually the open wire version, to feed the 144
MHz EME array. Even in a matched condition, it beats the pants off of coax
line in terms of lower loss and higher power handling ability.
It is as Will Rodgers once said; "Its not what folks know that concerns me,
it's what folks know that isn't correct that gives me concerns". There is
a LOT of incorrect information, published, written and said about these
lines that IS NOT correct.
Thanks, I'm with you on this one!
73
Bob, K4TAX
----- Original Message -----
From: "Steve Hunt" <steve@karinya.net>
To: "Discussion of Ten-Tec Equipment" <tentec@contesting.com>
Sent: Saturday, August 03, 2013 9:50 AM
Subject: Re: [TenTec] OT: Openwire/Window Line and Bad Wx
Bob,
Perhaps I had better explain clearly why I am carrying out these
ladderline tests.
I believe that the "wet" ladderline losses reported by Wes Stewart, and
those predicted by at least two of the popular on-line calculators, are
sufficiently high that some folk could be put off using the stuff. It
seemed to me important to understand: how Stewart arrived at his figures;
why Stewart's figures are so different from the ARRL measurements; what
sort of losses can be expected in practice.
That's all :)
73,
Steve G3TXQ
On 03/08/2013 14:37, Bob McGraw - K4TAX wrote:
Steve et al:
I'm not saying that loss does or does not change with the vinyl type
window line between wet and dry. I do agree with your results in that
loss does increase with a wet line as opposed to a dry line. I also
agree that loss is greater per unit at 28 MHz vs. the same length of line
at 1.8 MHz or 3.8 MHz regardless if the line is wet or dry.
My point, with today's receivers, in most all cases the atmospheric noise
and man made noise will mask any receiver internal noise and will easily
overtake any loss in the transmission line. However, the loss in the
transmission line will affect the NF of the receiver, which on HF is of
little significance. In many cases, we worry about 2 or 3 dB loss in
the transmission line but run the attenuator of 10 dB to 20 dB at the
input of the receiver. Now on transmit, that point makes a different in
the power arriving at the antenna. Again, typically less than 1 S unit
on the other end. To that point, most of the time I run the Argonaut VI
at 10 watts and can work about any station I hear, regardless of line
loss.
True open wire line, by definition, is two conductors supported only at
the source end and the termination end, drawn taught, and without any
spacers. This of course is a real challenge to make work reliably in
practice unless one uses large conductors and spaced at 6" to 18" and
used at lower frequencies and typically with very high power in the near
megawatt range. We used this feed line approach in some of the commercial
SW stations to which I attended. Some of these feed lines were each
several thousand feet in length. All of this is far beyond the scope of
most ham installations.
I would like to see more data on dry line vs. wet line from natural cause
as opposed to "wetted" line. I use the vinyl covered line with 66% of
the web spacers removed. {Remove 2, leave 1, remove 2, leave 1.} I see
little change from wet to dry on HF.
73
Bob, K4TAX
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