Hi Tom,
U've received many excellent suggestions for "shortened" 80 meter antennas
but here is one I haven't seen mentioned. At several locations over the
years I have used a combination antenna by Alpha-Delta called the DX-A. It
covers 160, 80 and 40 meters. Many people see the ad and believe it to be
a dipole-inverted vee however it is actually 3 slopers (trap loaded on 160
meters).
The DX-A is a great value, I couldn't purchase and assemble similar quality
components and wire separately for anywhere near the price u can buy the
whole setup for (about $60 U.S. at AES et al). It works extremely well on
a 50 foot tower, or any tower with the connector of the DX-A attached near
40-50 feet. At 50 feet u get a nice vertical type pattern on 80 and 40
meters, very good for DX work in my experience. U have to make sure ur
tower, or other center support, is well grounded (I also use several
radials tied into the ground system, but the radials aren't critical).
I am recommending this antenna for 80 and 40 primarily. The 160 meter
section works as well as any shortened vertical on 160 but u definitely
need separate receive antenna for Topband. I have used the DX-A at 3 prior
locations. I have a new one ready to go up here once we get the tower and
beams finished.
The DX-A is very installation dependent as far as pattern is concerned...ur
tower or other center support...must be well grounded. However I have
friends who have excellent success with the center at 30 feet, on 3
sections of Radio Shack TV mast, and ends drooping to 10 feet. The pattern
remains omnidirectional, as far as anyone that I know can tell. Almost
certainly, at 30 feet, the pattern is much closer to a very stubby inverted L.
There are better antennas for 80 meter DX work, like a 3 or 4 square, or
full size vertical dipole. But for those of us with limited resources in
tower height, I have not found a better DX antenna. At 50 feet or
less--let me know if u find anything that will work better for DX, I'm
always looking, aren't we all?
By the way, whatever u decide about 80 meter DX work. I would never be
without the ladder line fed dipole, for an all band antenna. U just need a
way to support the ends and center, it's very easy if u give it a little
thought. W4COX makes and sells one he calls "the w4rqz" (it's another one
of those rare antennas that are very hard to build cheaper than u can
buy). The W4RQZ dipole fits easily into 80 feet of length, u run solid
dielectric coax like RG213 out to the matching unit at the base of the
ladder line. About 30 feet of ladder line runs up from there to the
dipole, here is his web site: <http://w4cox.hypermart.net/>
73 and enjoy ur search!
Frank, KB8XU
>On Sat, 18 Aug 2001 Tom Anderson <ww5l@gte.net> writes:
> >
> > After taking a lightnming hit I'm redoing the antenna configuration
> > on my crank
> > up tower. One question is does anyone know how efficient a
> > shortened 80 meter
> > dipole/inverted vee (80 ft) is versus the advertised "full size" 80m
> > dipoles of
> > 130 ft or so? The highest I can get the apex of the dipole/inverted
> > vee is 50
> > ft. (I have a TriEx WT51 with a Mosley Classic 33 WARC (the the 40m
> > kit on the
> > driven element) on top. The reason for investigating the shortened
> > dipole/vee is
> > my lot is just 100X150 Any help appreciated, or would I be doing
> > better by
> > putting up a vertical?
> >
> > Tom, WW5L
> > Colleyville, Texas
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