On 5/17/2015 6:53 AM, Helmut Wabnig wrote:
hello,
I am a newcomer in amateur radio shortwave and so far
have built a dipole antenna with ladder line.
Not a G5RV, not a ZEPP, not a DOUBLE ZEPP, not a DOUBLETT,
but a dipole, a non-resonant antenna, if you know what I mean.
Unfortunately the antenna feedpoint is 25 meters away.
Now I am searching for a remote automatic tuner
for balanced feed line, aka hen's ladder, and coax input.
Presently I am using a BG-430 military Generalstab radio tuner.
http://www.radiomuseum.org/r/zellweg...em_se_430.html
It is the lower right foto, the thing in the center with the 4 black
feet. Works only 80 and 40 meters.
In more detail:
http://www.radiomuseum.org/r/zellweg...geraet_ag.html
Look at the schematic, upper part.
The input coax connects to the "balun" transformer,
and two variometer coils connect to the antenna output.
I have not been able to find anything useable on the market.
SGC tuners are ruled out, they are strictly for long wires
and nothing else. They make their money with the UN and other
mobile militaries, amateurs are not existent for them.
Amateurs use dipoles and ladder lines.
No, you can't use an SGC on a dipole.
If you do, you are wasting your money.
What rermains are MFJ and LDG coax tuners in combination
with a 1:4 balanced transformer. Thus the 25 m coax line would see
a fine SWR and no losses due to reflections. The coax from the tuner
output to the balun input make very short to avoid reflection losses.
Very high voltages will oscillate there!
What I like less is the balun at the high end, would prefer
a symmetric tuner with a balun at the coax input and balanced
symmetric output, like the Zellweger tuner does.
The MFJ-974HB is also a fine thing.
Really symmetrical at the tuning circuits, but manual.
100 Watt are fine, 400 Watt are better. (Maximum in Austria)
Can you help me, please?
OE8UWW
I do not believe you need a remote tuner. If you feed the antenna with
some home made 600 ohm line it will have an extremely low loss. See
latest QST on this issue. I run a 75 meter loop fed with 600 ohm line. I
have had much better success with this than when it was run with window
line or before that a dipole fed with coax.
I use that loop for all bands. It works very very well. I need a loop
because I live in the middle of town. I needed to phase out local noise
coming in from the horizontal plane.
Your dipole will work quite will with a tuner of just about any brand
that has a balanced output. The losses in that 25 meter run will be too
low to matter.