wrote in message
...
On Jan 11, 8:59 am, Cecil Moore wrote:
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
The 4:1 balun in the 989c is not a voltage balun. It's fairly
hefty current balun wound on a big toroid.
I've used the same one when I'm using mine for ladder line.
I got my 989c free because of heat damage. But it was
fried coil forms, rather than the balun.
I tediously repaired the coil, and have been using it ever
since. The coil in it is actually the second one.
The guy burned up two of them, and finally decided
to buy a big Nye Viking, and gave me the 989c as
junk trash.
But he abused the tuner by trying to run a 1/2 size
dipole on 75m, and also running a 8877.. :/
Not a good idea when using a T network tuner..
I guess the Nye Viking was a bit stouter, as I
don't recall him killing it. But I bet even it got a
bit toasty at times.
Anyway, being he never managed to kill one of
the baluns with his torture tests, I imagine they
are fairly stout. It is a "3 KW" tuner.. wink,wink.. :/
-----------
Yeah, it's a 3kw tuner when the SWR is 1:1. Lots of folks don't understand
that at all.
I don't mean to sound like a smart ass, but all of the techno-babble (which
I too have memorized) such as current balun - voltage balun -
blah-blah-blah, does not help me do what I am trying to do. I've read all of
that a thousand times at least, memorized it, passed tests on the
fundamentals, etc. It doesn't apply directly in this instance.
I'm looking for a way to multiply the range of impedances that can be
matched.
Yeah, I know. This is not in the handbooks, but it is what I'm trying to do.
And, it has been done with the MFJ-989C balun, so I know that it CAN be
done.
Don't believe me? Operate the 989C direct from a coaxial output into an
external balun and then run it through the wire output which has the alleged
4:1 balun in line. The difference in the loads that can be matched is
astounding.
Problem is, I can no longer enjoyably tune the MFJ-989C due to arthritis. I
am looking for a balun that will multiply the impedances that can be matched
so that I can use my MFJ and LDG high power autotuners. The stock baluns I
have used do not provide this ability with these autotuners. Nor can they be
equalled using the MFJ-989C straight thru, without the internal balun in
line. Pardon me if I'm repeating myself. Need sleep.
What doesn't help is that I'm only using about half of the 100' of 450 ohm
twinlead feedline that came with my Van Gordon All Bander. I just have no
other way to lengthen it, so I'm stuck using almost fifty feet of the
twinlead. I'm sure this compounds the problems that I am having.
On top of all of that, I want to be able to run about 600 watts output from
my amplifiers (one upstairs/one downstairs). Any thoughts/ideas would be
appreciated. I have thought of going with a fan dipole, but that will reduce
my operating bands by nearly one half.
Ed, N2ECW