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Old January 11th 09, 02:59 PM posted to rec.radio.amateur.antenna
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First recorded activity by RadioBanter: Mar 2007
Posts: 3,521
Default Installing a Ladder Line to the house

Ed Cregger wrote:
I have an LDG 1:1 200 watt
balun that will tune my Van Gordon All Bander from one end to the other of
the HF spectrum, using just the internal tuner of my Yaesu FT-890AT. Go
figure.


If this is the 80m dipole with 100' of ladder-line, one
can look at my notuner all-band-HF antenna to see why
100' is a good fixed length for the ladder-line. 100'
is near a current maximum point (loop) on all HF bands.
If one varies the length of the ladder-line from 90' to
115', one doesn't even need a tuner and a 1:1 current-
balun-choke is ideal.

http://www.w5dxp.com/pnts130.gif

To my way of thinking (which is probably incorrect), using the 4:1 balun
would broaden the impedances that I could match versus the 1:1 balun. What
you are saying is just the opposite. Please elaborate. I will be most
grateful.


A 4:1 balun is a very good transformer over a narrow range.
Most are voltage baluns that do not balance currents and
therefore do little to discourage common-mode currents. Test
a balun looking into 2000+j2000 and see what happens. One
of my 4:1 baluns got so hot I couldn't touch the case. The
best balun design, IMO, is one where flux in the ferrite
is caused only by common-mode current and not by
differential-mode current.

Here's some useful information:

http://www.dxengineering.com/TechArticles.asp?ID={3E5220F7-2D0F-45B5-85F7-3B654F804C4F}
--
73, Cecil http://www.w5dxp.com
 
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