[TenTec] OT: Openwire/Window Line and Bad Wx

[Rick - DJ0IP / NJ0IP]

It sounds as if you found their problem.
Maybe they did forget to multiply by 2.

I think more important than the absolute loss in openwire is how it fairs to
coax.
After all we don't really have any other choices.  We have to pick one of
these two.

If I ever inherit a ranch or farm, I will not use openwire.
I'll have coax-fed mono-banders for every band.
Until then I need as many bands out of each antenna as I can get.

Unfortunately I am unable to use openwire at this QTH.
Thus the current interest in OCFD.

73
Rick

-----Original Message-----
From: TenTec [mailto:tentec-bounces at contesting.com] On Behalf Of Steve Hunt
Sent: Monday, July 29, 2013 8:22 PM
To: Discussion of Ten-Tec Equipment
Subject: Re: [TenTec] OT: Openwire/Window Line and Bad Wx

ARRL literature has consistently underestimated the losses of ladderline.
For example, the matched losses quoted in the ARRL Antenna Book - at least
up to the 21st edition - are about one half the figure you arrive at from a
basic analysis of the copper losses.

The QST article "The lure of ladderline" also grossly underestimates the
ladderline losses. At 3.8MHz a 66ft dipole at a height of 30ft over average
ground has a feedpoint impedance of around 11-j964 Ohms; that would produce
a loss of 8.9dB in 50ft of Wireman 551 ladderline or 6.1dB in the superior
554, compared with 1.37dB quoted in the article. Even
600 Ohm open-wire line would have a loss of over 2dB with that load.

Don't get me wrong, I like balanced transmission lines; but be very wary
about any of the loss figures quoted by ARRL.

If you do the basic maths on the copper losses, you'll arrive at a matched
loss figure almost exactly twice the ARRL figure. Call me cynical but: did
ARRL forget that there are two conductors and failed to multiply by two?

Steve G3TXQ


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