Gary wrote:
Thanks Gary. I hadn't heard of a "center fed Zepp" before either and
your description of them being end fed and hanging down from airships
of WW2 correlates with what I'd heard.

The Zepp is an end-fed 1/2WL antenna. The Double Zepp is a center-fed
one wavelength antenna. An Extended Zepp is a 5/8WL end fed antenna. An
Extended Double Zepp is a 10/8WL center-fed antenna.
--
73, Cecil http://www.qsl.net/w5dxp

On 5 Jan 2005 16:57:56 -0800, "Cecil Moore" wrote:

Gary wrote:
Thanks Gary. I hadn't heard of a "center fed Zepp" before either and
your description of them being end fed and hanging down from airships
of WW2 correlates with what I'd heard.

The Zepp is an end-fed 1/2WL antenna. The Double Zepp is a center-fed
one wavelength antenna. An Extended Zepp is a 5/8WL end fed antenna. An
Extended Double Zepp is a 10/8WL center-fed antenna.

Thanks Cecil and to all who responded, I think I'll just put up a
center fed dipole and feed it with twinlead or ladder line and then
use the 4:1 balun in my antenna tuner.

73 Gary

Gary wrote:
Thanks Cecil and to all who responded, I think I'll just put up a
center fed dipole and feed it with twinlead or ladder line and then
use the 4:1 balun in my antenna tuner.

That is a very popular configuration and works for a lot of hams. You
may need to change the length of the feedline for optimum operation.
Some ideas and information are available on my web page at
http://www.qsl.net/w5dxp/notuner.htm

One case where a 4:1 balun doesn't function well is on dipoles that are
less than 1/2WL long. For instance, the impedance looking into the
feedline for a 102 ft. dipole used on 80m may range down to 10 ohms. A
4:1 balun tries to take that 10 ohms down to 2.5 ohms. Antenna tuners
are inefficient when trying to match such low impedance values.
--
73, Cecil http://www.qsl.net/w5dxp

After reading numerous posts, I built an EDZ for 20 using the '450 ohm'
ladder line and coax balun approach. Maybe I got lucky, I don't know but
when I hooked up the antenna analyzer I was surprised to see an SWR of 1.3:1
at 14.030 and the impedance was around 51 ohms. So far it does outperform my
old G5RV by a fair amount to it's favored direction (SW or NE). The antenna
is at 35 feet (wish my trees were higher, but they aren't). The only
downside I can see is this antenna has a very narrow beamwidth and the nulls
are quite pronounced, but that's what the G5RV is now for.


"Cecil Moore" wrote in message
oups.com...
Gary wrote:
Thanks Cecil and to all who responded, I think I'll just put up a
center fed dipole and feed it with twinlead or ladder line and then
use the 4:1 balun in my antenna tuner.

That is a very popular configuration and works for a lot of hams. You
may need to change the length of the feedline for optimum operation.
Some ideas and information are available on my web page at
http://www.qsl.net/w5dxp/notuner.htm

One case where a 4:1 balun doesn't function well is on dipoles that are
less than 1/2WL long. For instance, the impedance looking into the
feedline for a 102 ft. dipole used on 80m may range down to 10 ohms. A
4:1 balun tries to take that 10 ohms down to 2.5 ohms. Antenna tuners
are inefficient when trying to match such low impedance values.
--
73, Cecil http://www.qsl.net/w5dxp

Jim Leder wrote:
After reading numerous posts, I built an EDZ for 20 using the '450 ohm'
ladder line and coax balun approach. Maybe I got lucky, I don't know but
when I hooked up the antenna analyzer I was surprised to see an SWR of 1.3:1
at 14.030 and the impedance was around 51 ohms.

Odds are that your feedline is a multiple of half-wavelengths
plus 0.2 wavelength. If you know the VF and length, it would
be interesting to calculate how close you came to N.2 wavelengths.
--
73, Cecil http://www.qsl.net/w5dxp


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