Steve,
Without a doubt, Tom is 10x more knowledgeable than I am on antennas and
transmission lines, BUT...
He states: "Now in fairness I did not 'retune' the wet line with an antenna
tuner because the data was supposed to be for a 300 ohm line which we
generally *assume* is terminated in 300 ohms."
The devil is in the detail, but so is the answer: one should not make
assumptions. In real life we do "re-tune" the matchbox.
Engineers like to play with numbers, but we hams like to make contacts on
our radios.
We want to know how something works under normal circumstances, not how it
might behave in a hypothetical case.
If the line impedance changes due to anything, we retune our matchboxes.
If the antenna still works after that, good; no problem.
Joel stated that you had to retune the matchbox with windowline but not with
real openwire.
I guess the answer here depends on what you are looking for.
I've used windowline about 20 times in portable CQWW DX contest operations.
I've generally used homebrew (real) openwire when operating from home.
These contests are in the end of October / end of November.
Many of the years I was operating portable in Liechtenstein (with
windowline), and we got snow, rain, sleet, etc.
If my antenna's performance (after re-tuning the matchbox) had been losing
6dB, that would have been like turning the linear off. Believe me, in a
contest, in a pileup you notice 6dB difference. I never did, so I don't
believe the performance drops 6dB.
Joel's results support my field experience using this feedline at HF
frequencies.
We still have one big disconnect here: "frequency"
The only measured test results that I've seen while following this thread
were made at 50 MHz and above.
We all know that losses in transmission lines go up rapidly as frequency
increases.
Are there any published test results for 14 MHz or 21 MHz?
For this thread I'm interested in the HF apples, not the VHF oranges. :-)
73
Rick
-----Original Message-----
From: tentec-bounces@contesting.com [mailto:tentec-bounces@contesting.com]
On Behalf Of Steve Hunt
Sent: Thursday, January 26, 2012 11:06 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] Re. [Ten Tec] Grounds and balanced fed verticals
Rick,
When W1ZR's article appeared in the November 2009 QST it was *very*
controversial. Here's an example of the typical debate it engendered:
http://www.eham.net/ehamforum/smf/index.php?topic=44059.0
In that QST article Joel states that the loss measurements he made on
dry line "agreed with TLW predictions within a few tenths of a dB".
Given that a simple calculation involving Ohms Law will tell you that
the TLW predictions are wrong by a large margin, that must cast serious
doubt on his measurement technique.
73,
Steve G3TXQ
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