Amerigo Vespucci wrote:
"Cecil Moore" wrote in message
t...
Amerigo Vespucci wrote:
The way I understood it was the best way to feed it was with ladderline
or something equal to it.
Did anyone tell you that the matching section needs to be
about 0.2 wavelength?

Explain?

To make an EDZ system resonant, i.e. a resistive impedance
looking into the feedline, the ladder-line needs to be
about 0.2 wavelengths long (plus N*1/2 wavelengths).
--
73, Cecil http://www.w5dxp.com

wrote in
ups.com:

On Jul 15, 9:41 am, "Amerigo Vespucci" wrote:
I constructed an extended double zepp for
10 meters out of #12 solid house wire .
I didn't have any ladder line laying around so I decided to make my
own but all I had was some #10 stranded wire. I made the spacers 1"
apart and and put about one per foot and the total feedling is
approximately 25 ft. and it's going through an MFJ 941E Versatuner .
I can't get my SWR's below 2 . I'm sure there are a lot of varibles
here but I was hoping someone could point me in the right
direction.My first guess is that I should have used the #12 for the
feedline and the #10 for the antenna .
Thanks in advance ,
Will

Seems kind of strange the tuner would not match it..
The spacing probably has more effect on the feedline Z
than the wire diameter. Shouldn't really be that critical.
The wider the spacing, the higher the Z..
I guess you could try a different length of line..
Or scrounge up some other ladder line, maybe with a
different length. Even 300 TV line would be ok if it's
not wet.
Myself, I used to feed them with coax, and coax
series transformers. I imagine you could also feed
with coax and use twin matching coils at the feedpoint
for both sides of the element. Same as matching a
5/8 GP, you are just doing the same with a complete
antenna. I've never tried it, but it should work.

My very first antenna project was a straight 20m zepp, end fed with
homebrew 600-ohm line 1/4 wave long just like in the books. I never ever
measured the SWR or even transmitted on it, but it was one GREAT
receiving antenna for 20m (that was in my SWL days).


--
Dave Oldridge+
ICQ 1800667

On Sun, 15 Jul 2007 14:41:33 GMT, "Amerigo Vespucci"
wrote:

I constructed an extended double zepp for
10 meters out of #12 solid house wire .
I didn't have any ladder line laying around so I decided to make my own but
all I had was some #10 stranded wire. I made the spacers 1" apart and and
put about one per foot and the total feedling is approximately 25 ft. and
it's going through an MFJ 941E Versatuner .
I can't get my SWR's below 2 . I'm sure there are a lot of varibles here but
I was hoping someone could point me in the right direction.My first guess is
that I should have used the #12 for the feedline and the #10 for the antenna
.
Thanks in advance ,
Will

For what it's worth, a graph in one of my older ARRL antenna books
says #10 wire at 1-inch spacing should have a characteristic impedance
a little under 400 ohms.

bob
k5qwg