Reg Edwards wrote:

The moral is - DON'T USE A G5RV.

Specially one with any coax in the feedline.

If you've bought one, you've been robbed.

It's a pretty good antenna for 80m, 40m, & 20m. My web page shows
how the "matching section" gives a pretty good match to coax on
80m and 40m. Mine also worked well on 12m.
--
73, Cecil http://www.qsl.net/w5dxp



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Hi:
That could be DON'T USE A 80M DIPOLE ON 160. I put up some dipoles for the
PAQSO party and I wanted something better than a 80m dipole and a tuner on
160m. So I put up a fan dipole with one of the dipoles a loaded dipole
(shortened to 200') for 160m.
Before I did that I had one of my local friends look at my signal strength
on my 80m dipole and tuner.
The new antenna was resonate with low SWR in the part of the band used by
the PAQSO party and when we did the same check, the new antenna was 25db
stronger. Why was that? Modeling the 80m dipole on 160m, it showed a Z of
9.2-J1127 Ohms at 1.85MHz. Using the program TL with a 9913 type feedline at
a length of 135' showed an excess loss due to the high SWR of 14.5db. Then
going to the tuner part of the TL program it calculated a loss of 6.8db
through the tuner for a total loss of 21.3db through the system. This is
very close to what we measured, completely in the within the margin of error
of the simple measurement like we did. More importantly I could hear band
noise that I could never hear before. Feeding it with open wire line would
have worked much better as the excess loss in the feed line would have be
1.8db with 5.2db loss in the tuner for a total loss of 7.01db. But with my
loaded dipole I need no tuner in the part of the band I operated in. The
losses in the loading coil are about 1db so my total system loss is less
than 2db, which is better than a 80m dipole and tuner, or even one feed with
open wire line and a tuner. It just shows there are no free lunches in
antennas and every chouse comes with a cost, in my case it's bandwidth and
loss in loading coils. I looked at the various kinds of antennas I could
use, picked what would work best for me.



--
John Passaneau, W3JXP
Penn State University


"Cecil Moore" wrote in message
...
Reg Edwards wrote:

The moral is - DON'T USE A G5RV.

Specially one with any coax in the feedline.

If you've bought one, you've been robbed.

It's a pretty good antenna for 80m, 40m, & 20m. My web page shows
how the "matching section" gives a pretty good match to coax on
80m and 40m. Mine also worked well on 12m.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote in message ...
Reg Edwards wrote:

The moral is - DON'T USE A G5RV.

Specially one with any coax in the feedline.

If you've bought one, you've been robbed.

It's a pretty good antenna for 80m, 40m, & 20m. My web page shows
how the "matching section" gives a pretty good match to coax on
80m and 40m. Mine also worked well on 12m.

I guess if a 2 S+ unit deficit compared to a coax fed dipole is
"pretty good", maybe so..."The average 2 s unit loss I saw was on 40,
not 80. 80 would have been worse. I remember a field day about 4-5
years ago where they used a G5RV on 80m. This particular one,
commercially made, was pitiful. My mobile antenna would have trounced
it...Was totally useless for us. I was so disgusted, I was gritting my
teeth. If I'm going to sit out in the sticks and eat bugs at night,
I'll be danged if I'm going to use a dummy load with wires attached.
:/ I decided that year, I'd never be stuck on anything like that
again. EVER! I have better things to do with my time otherwise. From
then on, I always bring the goodies along to build my own dipoles on
site. I have heard some on the air that seemed "ok", but the ones I've
ever seen and tried were horrible. 20 meters is about the only band
where I could see one being half decent, and even there, I bet the
average coax fed dipole would beat it. At least as far as overall
system efficiency. Who cares about a EDZ type pattern...
To each his own I guess....BTW, most G5RV's that sound "ok" on 75m,
have KW amps behind them...:/ Stick a barefoot radio on one,
and.......zzzzzzz. There are some exceptions, but most have been
converted to a total ladder line feed. MK

Mark Keith wrote:

Cecil Moore wrote:
It's a pretty good antenna for 80m, 40m, & 20m. My web page shows
how the "matching section" gives a pretty good match to coax on
80m and 40m. Mine also worked well on 12m.

I guess if a 2 S+ unit deficit compared to a coax fed dipole is
"pretty good", maybe so..."The average 2 s unit loss I saw was on 40,
not 80. 80 would have been worse. I remember a field day about 4-5
years ago where they used a G5RV on 80m. This particular one,
commercially made, was pitiful. My mobile antenna would have trounced
it...Was totally useless for us.

Of course, the quality of a G5RV makes a difference. Knowing all you do
about dipoles, I'll bet you could design a G5RV that is virtually
identical in performance to a dipole on 75m and 40m. The losses due
to SWR are pretty negligible using RG8x.

One note, however. The G5RV's null off the end of the antenna is about
6dB deeper than a 1/2WL dipole on 40m. Perhaps that explains part of
your findings.
--
73, Cecil http://www.qsl.net/w5dxp



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Cecil Moore wrote in message
I'll bet you could design a G5RV that is virtually
identical in performance to a dipole on 75m and 40m. The losses due
to SWR are pretty negligible using RG8x.

The only way to do that and keep a dipole pattern on both bands is to
run parallel dipoles on one coax. And thats what I run. If I only have
room for one wire, I'll make a dipole for the lowest band, and
"jumper" the higher bands, using insulators and clips to bypass them.
Still dipole performance for each band...

One note, however. The G5RV's null off the end of the antenna is about
6dB deeper than a 1/2WL dipole on 40m. Perhaps that explains part of
your findings.

Nope, don't think so. Wouldn't that be on 20m? We used it on 80m. The
pattern should have been about the same as the dipole, considering
it's shorter than the dipole by 20-30 ft. The problem with the one we
ran was feedline and tuner losses. It made my 100w feel like 10w at
the rate we were cutting through the summer noise. Worst antenna I've
ever used on that band. What I never could understand is why we
were using a "compromise" antenna out on field day, when we have
enough room for anything. That seemed to be the normal pattern every
year, until I put my foot down..."for me to use personally" I never
could fathom that, when a dipole is only 20-30 ft longer, and the
overall efficiency is usually a large magnitude greater. Like I said,
after that field day, and all my lost hair from pulling it out, I said
never, ever, again.
If anyone wants to run one of those compromise antennas, G5RV,
windoms, etc, etc, be my guest. But don't expect me to use it. I'll
run like anthrax spores are on the radio. I can't afford to lose
any more hair. MK