I've looked at some commercial "full size" G5RV's and the leg lengths
are about 51 feet long each, that seems a tad short for 80 meters.
Would I experience quite a bit of loss in the tuner ( External ) Or
maybe I should try and erect a dipole with leg lengths as long as I
can and feed it with 450 Ohm Ladder line or 300 Ohm twinlead and be
able to operate on 30 meters ? I understand the G5RV doesn't work too
well for 30 meters, and I need some place to operate during contests.
My primary bands of interests are 80 thru 20 CW.

Thanks in advance.

Gary K8IQ

On Tue, 28 Dec 2004 02:36:11 -0500, Gary wrote:

I've looked at some commercial "full size" G5RV's and the leg lengths
are about 51 feet long each, that seems a tad short for 80 meters.
Would I experience quite a bit of loss in the tuner ( External ) Or
maybe I should try and erect a dipole with leg lengths as long as I
can and feed it with 450 Ohm Ladder line or 300 Ohm twinlead and be
able to operate on 30 meters ? I understand the G5RV doesn't work too
well for 30 meters, and I need some place to operate during contests.
My primary bands of interests are 80 thru 20 CW.

Thanks in advance.

Gary K8IQ

Dear Gary,

When G5RV designed that antenna, it was designed for 20 meters.
What does that tell you?

Your own suggestion is a pretty good one. However, don't expect that
you will be lucky enough to have it tune to 1:1 on all frequencies,
just because you use a balanced feedline and a tuner. Usually, some
matching is necessary with discrete elements or transmission line
segments, stubs, etc.

If you want to take advantage of the extensive work of others on the
"all purpose" center fed dipoles, take a look at Cecil's web site.
Bob, W9DMK, Dahlgren, VA
http://www.qsl.net/w9dmk

On Tue, 28 Dec 2004 02:36:11 -0500, Gary wrote:

I've looked at some commercial "full size" G5RV's and the leg lengths
are about 51 feet long each, that seems a tad short for 80 meters.

That's because the "missing" portions are in the open wire section.
It still works at 80m and can be fed with 75ohm coax at the lower end
of the line via a 1:1 balun. Better still would be to bring the open
wire section into the shack and to an ATU.

From what I remember from using one of these many, many years ago, I
used 29ft 6 inches of 300 ribbon feeder as against 32 - 33 ft of open
wire (300 ohm ribbon has different velocity factor to the open wire
and 450 ohm ladderline)

Would I experience quite a bit of loss in the tuner ( External ) Or
maybe I should try and erect a dipole with leg lengths as long as I
can and feed it with 450 Ohm Ladder line or 300 Ohm twinlead and be
able to operate on 30 meters ?

Yes ... and use the 450 ohm ladder line

I understand the G5RV doesn't work too
well for 30 meters,

It was never designed for that band as we didn' have that allocation
when Louis, G5RV, introduced the antenna. That's why it's best to use
open wire right down to the shack. You can then use it on all of
todays HF bands via an ATU. The 102 foot "top" is also no magic then.
Make the legs as long as you can .... you might even be able to work
160 metres if you can get out enough wire!

BTW, please dont buy a G5RV !!! They are so easy to make and work out
cheaper. You also have the satisfaction that you made it yourself,
which is what amateur radio is (hopefully largely) about.

Have you considered putting up a 50 ohm coax fed inverted V 80 metre
dipole and then adding a 40 metre dipole to the same coax feed point?
It can come down at a sharper angle than the 80m one or run at right
angles to it. You'll then have 80, 40 and 15 metres since the 40m
dipole will work has 3 half waves in phase on 15. You can hang dipoles
for the other bands to the same feeder as well. Be prepared for some
cut 'n try of course! This system elimates the need for an ATU but
you'll find the usable bandwidth on 80m to be only just a couple of
dozen kHz or so. The open wire version will be tuneable across the
whole of each band via the ATU.

Good luck,

Peter, G3PHO

Gary wrote:
I've looked at some commercial "full size" G5RV's and the leg lengths
are about 51 feet long each, that seems a tad short for 80 meters.
Would I experience quite a bit of loss in the tuner ( External ) Or
maybe I should try and erect a dipole with leg lengths as long as I
can and feed it with 450 Ohm Ladder line or 300 Ohm twinlead and be
able to operate on 30 meters ? I understand the G5RV doesn't work too
well for 30 meters, and I need some place to operate during contests.
My primary bands of interests are 80 thru 20 CW.

Hi Gary, take a look at http://www.qsl.net/w5dxp/notuner.htm for some
information and ideas.
--
73, Cecil, W5DXP


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Peter wrote:

On Tue, 28 Dec 2004 02:36:11 -0500, Gary wrote:
I've looked at some commercial "full size" G5RV's and the leg lengths
are about 51 feet long each, that seems a tad short for 80 meters.

That's because the "missing" portions are in the open wire section.

Why the G5RV works well on 75m is explained using a Smith Chart on my
web page at: http://www.qsl.net/w5dxp/G5RV.HTM where it can be seen
that the series twinlead matching section transforms the antenna
feedpoint impedance of 36-j324 ohms to a resonant impedance of 17 ohms.
Even better is to install a 1000 pf cap across the line at the coax to
twinlead junction to achieve a near perfect match on 75m (remove for
use on the higher bands).
--
73, Cecil, W5DXP


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Peter wrote:


Have you considered putting up a 50 ohm coax fed inverted V 80 metre
dipole and then adding a 40 metre dipole to the same coax feed point?
It can come down at a sharper angle than the 80m one or run at right
angles to it. You'll then have 80, 40 and 15 metres since the 40m
dipole will work has 3 half waves in phase on 15. You can hang
dipoles
for the other bands to the same feeder as well. Be prepared for some
cut 'n try of course! This system elimates the need for an ATU but
you'll find the usable bandwidth on 80m to be only just a couple of
dozen kHz or so.

Should be wider than that...I usually get 200-250-300 kc "2:1 SWR" on
80m,
using common fed dipoles. About the same as a single dipole...I just
checked
mine out of curiosity, and I'm tuned at about 3910kc. Using the SWR
meter
in the rig, I hit 2:1 at about 3.810. Actually, I usually tune about
3850 or
so, but it seems to have changed a bit, probably cuz a large tree was
cut down,
and I had to change the antenna layout a bit. But anyway, I'm getting
3.810
to 4.000 usable with no tuner if you consider 2:1 the limit. I am using
an
MFJ 989c tuner, but usually only for the wattmeter...But I can use it
to go
off the beaten path.. Right now, I've got 160,80,40 on one coax feed. I
can
use the tuner for any of the other bands. Even with the coax loss, it
usually
works ok about anywhere. Works real well on 30m, even though the SWR is
about
5:1 or so..At that freq, and the rg-213 I use, 5:1 doesn't add too
awful much
loss. I get real good reports. Running the different dipoles at right
angles
is the best, with almost zero interaction. As they start to parallel,
the
coupling between them will increase, but is usually no big deal.

It's best to always start, and tune the lowest band first, and then add
and
tune each higher band dipole as you go along. Thats the fastest and
easiest
way. If you have coupling problems, it will almost always show up on
the
higher band dipole. Almost never on the lower. IE: An 80 and 40 dipole
on
the same feed, would usually show any coupling/tuning problems on 40m.
Often,
just moving one of the 40 legs a few feet farther away will let it tune
fairly
normally. Once set up, and tuned, the performance of the paralleled
dipoles
will usually outdo most tuner driven/ladder line fed single dipoles. No
tuner losses, no knob fiddling, and you have a normal dipole pattern on
each
of the bands used. It's been my preferred setup for years as far as my
"everyday" lower band antennas. The efficiency is in the 95%+- range
depending
on the band..."I use 213 coax" Can't really improve on that much..Even
lowly
rg-58 will be pretty low loss on the lower bands, as long as the length
is
not excessive. MK

On Tue, 28 Dec 2004 12:59:44 -0600, Cecil Moore
wrote:

Gary wrote:
I've looked at some commercial "full size" G5RV's and the leg lengths
are about 51 feet long each, that seems a tad short for 80 meters.
Would I experience quite a bit of loss in the tuner ( External ) Or
maybe I should try and erect a dipole with leg lengths as long as I
can and feed it with 450 Ohm Ladder line or 300 Ohm twinlead and be
able to operate on 30 meters ? I understand the G5RV doesn't work too
well for 30 meters, and I need some place to operate during contests.
My primary bands of interests are 80 thru 20 CW.

Hi Gary, take a look at http://www.qsl.net/w5dxp/notuner.htm for some
information and ideas.

Thanks to all that resonded. I'll have to do some antenna work when
the snow melts and we get some warmer weather in Michigan this spring.

Thanks again

73 Gary K8IQ

Dear Neighbor Gary:
Snow will melt over the next two days and it will be above freezing. Heat
wave in Michigan. Could be worse in the Spring.

with tongue-in-cheek, 73 Mac N8TT

--
J. Mc Laughlin; Michigan U.S.A.
Home:



Thanks to all that resonded. I'll have to do some antenna work when
the snow melts and we get some warmer weather in Michigan this spring.

Thanks again

73 Gary K8IQ