Hi,

I used a multiband dipole G5RV 31M (100') with balun 4:1 during the last CQ
WW.
I also wrote a text about its uses so I understand quite well how it works,
excepting when it doesn t work...

I.e. For tests I tried to use it on the 160m band where the dipole is not
cut for with the hope to be able to work at least some near stations (over
the skip distance). Thay worked well with a longwire 30m long, so I
suspected that that could work with this one too. Negative.

At the output of my RTX the signal was strong, 100W PEP, but at first sight
no signal was emitting by the antenna.
I have found nowhere an information about this, no diagram or whatever.

What becomes all the energy sent by my TX on 160m ? What become de standing
waves and reactive load ? Is it possible than all 100W are lost in the coax
or the feeder without be emitted ?

Who could explain me this ?

Thanks

Thierry
ON4SKY

What becomes all the energy sent by my TX on 160m ? What become de standing
waves and reactive load ? Is it possible than all 100W are lost in the coax
or the feeder without be emitted ?

As I understand it, this is a very common problem if you try to feed a
doublet antenna which is quite a lot shorter than 1/2 wavelength. The
antenna presents a highly capacitive load to your tuner. If your
tuner does manage to match it, you'll end up with extremely high SWR
on the feedline, and very high currents flowing in the tuner's
inductive component(s). Most of your transmitter's power is being
dissipated as heat, due to the resistive losses in the feedline and in
the tuner inductor(s).

Trying to drive a too-short doublet has been the cause of more than
one thoroughly-destroyed antenna tuner - the heat dissipation can
crack toroid cores, melt the plastic forms in roller inductors, etc.

--
Dave Platt AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!

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.

Use a random length dipole, longer than about 1/3 of the wavelength at the
lowest frequency of interest. Choose a length which makes best use of the
size of your backyard. Take the 450 or 600-ohm balanced line all the way
back to the shack. You will need a tuner and a choke balun at the tuner.
For multi-band operation you will need a tuner whatever you do.

If you find it inconvenient to feed the dipole in the middle, and you have a
relatively low local noise level, then feed it at one end and make an
Inverted-L of it. It will then very likely work very well also on 160
metres.

And you will never think of using a G5RV again !

By the way - Louis Varney, G5RV, a real genuine English gentleman, now no
longer with us, designed his antenna to work most efficiently ONLY on 14.15
MHz, perhaps the best day-or-night, all-year-round, any part of the sun-spot
cycle, DX frequency. It's very good. And you may not need tuner even with
the coax. Works great with the old fashioned TS-520 with its built-in tuner
!
----
Reg, G4FGQ

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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"Reg Edwards" wrote in message
...
The moral is - DON'T USE A G5RV.


Yup! I bought one in the late 80s and found that it was the craziest acting
thing I had ever used! It most often
drove my Yaesu tuner bonkers; other times it would
settle down to an "acceptable" SWR. I fiddled with it
for a summer, and finally threw it out. I then made me a
75 M doublet fed with ladder line. .......it's still up there.

Jerry
K4KWH

Specially one with any coax in the feedline.

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

Use a random length dipole, longer than about 1/3 of the wavelength at the
lowest frequency of interest. Choose a length which makes best use of the
size of your backyard. Take the 450 or 600-ohm balanced line all the way
back to the shack. You will need a tuner and a choke balun at the tuner.
For multi-band operation you will need a tuner whatever you do.

If you find it inconvenient to feed the dipole in the middle, and you have
a
relatively low local noise level, then feed it at one end and make an
Inverted-L of it. It will then very likely work very well also on 160
metres.

And you will never think of using a G5RV again !

By the way - Louis Varney, G5RV, a real genuine English gentleman, now
no
longer with us, designed his antenna to work most efficiently ONLY on
14.15
MHz, perhaps the best day-or-night, all-year-round, any part of the
sun-spot
cycle, DX frequency. It's very good. And you may not need tuner even with
the coax. Works great with the old fashioned TS-520 with its built-in
tuner
!
----
Reg, G4FGQ

"Reg Edwards" wrote in message
...
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.

Hi,
At first sight you never uses a G5RV. You opinion is completely false and
will induce novices (and other if I beleive you) in error.
So read this and learn from the master, G5RV himself :
http://www.astrosurf.com/lombry/qsl-g5rv.htm

I confirmed over 250 DXCC in one year with the G5RV at less than 100 W PEP
from 80 to 10m, including WARC. It works ! Not as a beam of course. But very
well for what it cost (about 100 euros). That stays an excellent
investissment, not necessary if you are hunting DX (away that to say 8000 km
in low solar acticvities like now) or want to participate in all contests
(that stays a dipole than I work barefoot) but for ragchewing in local QSO
(inside a radius of to say 5000 km) it is perfect. With an average emitting
power of 50W or so, most hams receive me in voice 59 or more, even 57 up to
VE, east K, VP5, FY, YB. More far the signal decreases (53 and less). But
this is a beam after all.

Thierry
ON4SKY, LX3SKY



Use a random length dipole, longer than about 1/3 of the wavelength at the
lowest frequency of interest. Choose a length which makes best use of the
size of your backyard. Take the 450 or 600-ohm balanced line all the way
back to the shack. You will need a tuner and a choke balun at the tuner.
For multi-band operation you will need a tuner whatever you do.

If you find it inconvenient to feed the dipole in the middle, and you have
a
relatively low local noise level, then feed it at one end and make an
Inverted-L of it. It will then very likely work very well also on 160
metres.

And you will never think of using a G5RV again !

By the way - Louis Varney, G5RV, a real genuine English gentleman, now
no
longer with us, designed his antenna to work most efficiently ONLY on
14.15
MHz, perhaps the best day-or-night, all-year-round, any part of the
sun-spot
cycle, DX frequency. It's very good. And you may not need tuner even with
the coax. Works great with the old fashioned TS-520 with its built-in
tuner
!
----
Reg, G4FGQ

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

"Jerry" wrote in message
.. .

"Reg Edwards" wrote in message
...
The moral is - DON'T USE A G5RV.


Yup! I bought one in the late 80s and found that it was the craziest
acting
thing I had ever used! It most often
drove my Yaesu tuner bonkers; other times it would
settle down to an "acceptable" SWR. I fiddled with it
for a summer, and finally threw it out.

Hi,

Sorry to say that but you experimented a bad experience or have not enough
knowledge to use it properly.
I know several OM in ON that use G5RV, W3DZZ and alike, and even longwire of
about 20-30m that have similar results than mine.
And if the G5RV is always sold (thare a dozen variantes, see my website)
after decades, there is a good reason : this is because it works well !

Never hear on bands OM working with dipole and G5RV ? There are a lot !
better, G5RV offer you the best quality/price ratio !

73's

Thierry
ON4SKY

I then made me a
75 M doublet fed with ladder line. .......it's still up there.

Jerry
K4KWH

Specially one with any coax in the feedline.

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

Use a random length dipole, longer than about 1/3 of the wavelength at
the
lowest frequency of interest. Choose a length which makes best use of
the
size of your backyard. Take the 450 or 600-ohm balanced line all the way
back to the shack. You will need a tuner and a choke balun at the tuner.
For multi-band operation you will need a tuner whatever you do.

If you find it inconvenient to feed the dipole in the middle, and you
have
a
relatively low local noise level, then feed it at one end and make an
Inverted-L of it. It will then very likely work very well also on 160
metres.

And you will never think of using a G5RV again !

By the way - Louis Varney, G5RV, a real genuine English gentleman, now
no
longer with us, designed his antenna to work most efficiently ONLY on
14.15
MHz, perhaps the best day-or-night, all-year-round, any part of the
sun-spot
cycle, DX frequency. It's very good. And you may not need tuner even
with
the coax. Works great with the old fashioned TS-520 with its built-in
tuner
!
----
Reg, G4FGQ

Thierry wrote:
But I wonder that having a SWR 1:1, nothing looks wrong (not heat, etc at
first sight), but the result is 0.0 on that band !!

The SWR between your final amp and the antenna tuner is 1:1. The SWR
on the feedline to the antenna is sky high.
--
73, Cecil http://www.qsl.net/w5dxp



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