Elecraft. G5RV Question

[Martin.Evans]

Hi Guys, my main rig is a K1 feeding a multi dipole for 80/40/20 with no
ATU. I am thinking of taking down the dipoles and trying a full size G5RV.
Questions:

   Will the KAT1 ATU tune up on all bands from 80-15m

   I will be using about 80 feet of 50ohm coax to get from the matching
   section to the rig, am I going to get big losses in the coax due to the
   high SWR on most bands? The beauty of the G5RV is that it can be fed
   with coax but with only 5W I don't want to waste all the power in the
   feeder.

   I intend to build the G5RV myself (like all of my antennas), how
   accurate does the length of the matching section have to be? does it
   need tuning in some way. Can I use any insulated wire for the open wire
   section?


The multi dipoles have been great performers but it's a lot of wire up
there and very heavy, I thought that with the G5RV being one single top
wire it will be lighter and I may be able to get it higher.

Any thoughts would be appreciated.


Why not take a look at our Web site?
http://www.simoncarves.com

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[Don Wilhelm-3]

While the G5RV has a lot of advocates for multiband use, it works much
better if you bring the parallel feedline all the way to the tuner.  When
used for multiband, with coax and the matching section, you will likely find
a higher than desirable SWR on the coax except on 20 meters.  I have found
the claims for the G5RV antenna to be highly exaggerated.  For good unbiased
information on the G5RV (or most any other antenna for that matter) check
out the wealth of information gained by modeling at L B Cebik's website
www.cebik.com.

Your multi-dipole will be more efficient on 80 meters, and can be fed
directly with coax and no tuner.  If I were in your shoes, I would leave
well enough alone unless there is some other overriding reason to change it.

73,
Don W3FPR

> -----Original Message-----
>
>
> Hi Guys, my main rig is a K1 feeding a multi dipole for 80/40/20 with no
> ATU. I am thinking of taking down the dipoles and trying a full size G5RV.
> Questions:
>
>    Will the KAT1 ATU tune up on all bands from 80-15m
>
>    I will be using about 80 feet of 50ohm coax to get from the matching
>    section to the rig, am I going to get big losses in the coax due to the
>    high SWR on most bands? The beauty of the G5RV is that it can be fed
>    with coax but with only 5W I don't want to waste all the power in the
>    feeder.
>
>    I intend to build the G5RV myself (like all of my antennas), how
>    accurate does the length of the matching section have to be? does it
>    need tuning in some way. Can I use any insulated wire for the open wire
>    section?
>
>
> The multi dipoles have been great performers but it's a lot of wire up
> there and very heavy, I thought that with the G5RV being one single top
> wire it will be lighter and I may be able to get it higher.
>
> Any thoughts would be appreciated.
>
>

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[Steve Hostetler]

Martin,
Before going to a G5RV, I would try feeding your 80 m dipole with 450
ladder line to a (good) 1:1 current balun and use a short run of coax to
the K1.  I use this setup to feed 102' and 44' wires.  My Ks tune them
on any of the bands they cover (you need a bit of additional L/C help on
160) and they work great.at QRP levels.

73, steve, kx7r

[hidden email] wrote:

>Hi Guys, my main rig is a K1 feeding a multi dipole for 80/40/20 with no
>ATU. I am thinking of taking down the dipoles and trying a full size G5RV.
>Questions:
>
>   Will the KAT1 ATU tune up on all bands from 80-15m
>
>   I will be using about 80 feet of 50ohm coax to get from the matching
>   section to the rig, am I going to get big losses in the coax due to the
>   high SWR on most bands? The beauty of the G5RV is that it can be fed
>   with coax but with only 5W I don't want to waste all the power in the
>   feeder.
>
>   I intend to build the G5RV myself (like all of my antennas), how
>   accurate does the length of the matching section have to be? does it
>   need tuning in some way. Can I use any insulated wire for the open wire
>   section?
>
>
>The multi dipoles have been great performers but it's a lot of wire up
>there and very heavy, I thought that with the G5RV being one single top
>wire it will be lighter and I may be able to get it higher.
>
>Any thoughts would be appreciated.
>
>
>Why not take a look at our Web site?
>http://www.simoncarves.com
>
>*************************************************************************
>The information in this email and any attachments may contain
>privileged and/or confidential information intended solely for
>the use of the individual or entity to whom it is addressed.
>If the reader of this email is not the intended addressee, or the
>employee or agent responsible to deliver it to the addressee,
>you are hereby notified that any dissemination, distribution or
>copying of this communication is strictly prohibited.
>If you have received this communication in error, please notify
>me by telephone or email and delete all copies immediately.
>*************************************************************************
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[Mike Morrow-3]

It was stated:

> Hi Guys, my main rig is a K1 feeding a multi dipole for 80/40/20 with no
> ATU. I am thinking of taking down the dipoles and trying a full size G5RV.

Don wrote:

> ... I have found the claims for the G5RV antenna to be highly exaggerated.
> For good unbiased information on the G5RV (or most any other antenna for
> that matter) check out ... www.cebik.com.
>
> Your multi-dipole will be more efficient on 80 meters, and can be fed
> directly with coax and no tuner.  If I were in your shoes, I would leave
> well enough alone unless there is some other overriding reason to change it.

IMHO, no truer words can be spoken.  I've never understood the popularity of the G5RV.  I'd agree in saying that your current array has the greater advantage over the proposed G5RV.

73,
Mike / KK5F
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[Joseph Trombino, Jr]

>> Hi Guys, my main rig is a K1 feeding a multi dipole for 80/40/20 with no
>> ATU. I am thinking of taking down the dipoles and trying a full size
>> G5RV.
>> Questions:
>>
>>   Will the KAT1 ATU tune up on all bands from 80-15m
>
> ----------------------snip----------------------
>
> Howdy Martin:
>
> Since you are planning on using a tuner anyway why not just put up a
> center fed doublet cut for the longest frequency you want to operate on,
> say 80m.
>
> Using a balanced tuner like the ZM2 Z-match tuner with this antenna will
> prove very effective...better than the G5RV I believe.
>
> Remember, the original G5RV was designed to provide a couple of DB's of
> gain on 20m only.....it was later re-designed a bit to provide multi-band
> coverage.....certainly not an optimum antenna by any means.
>
> I currently use a 170ft center fed (ladder line) doublet (extended Double
> Zepp on 40m) with a balun and remote tuner and it is the best wire antenna
> I have ever put up.
>
> Right now your multi-dipole antenna is about as good as you can get for
> multi-band coverage and you don't need a tuner with it....so your system
> is pretty darn good as it is.
>
> Best of luck with your decision.
>
>                                        73, Joe W2KJ

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[Leigh L. Klotz Jr WA5ZNU]

What is the difference between the G5RV and the twinlead-fed 102'
doublet with a current balun at the coax-to-balanced transition
mentioned as an alternative?  Is it just the random length of twinlead
rather than a calculated length?  Or is it a long run of coax vs. a
short one?

I know some people with G5RV's advocate a long coax run, but that just
adds loss, so I kept mine as short as possible.  Mine works ok on the
low bands, but poorly on 15m and up.  Wouldn't an 80m dipole be even
worse, with many more strange lobes?

Leigh / WA5ZNU
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[Craig Rairdin]

> Your multi-dipole will be more efficient on 80 meters, and can be fed
> directly with coax and no tuner.  If I were in your shoes, I would leave
> well enough alone unless there is some other overriding reason to change
it.

FWIW I had a multi-band trap dipole from Spi-Ro that worked OK but was
frustrating because it seemed "multiband" meant "equally bad on all bands".
There wasn't a single ham frequency at which it was naturally resonant --
thought it had many non-ham-band resonant frequencies.

I replaced it with a 40/20/10 multi-dipole which can be coax-fed and is well
under 2:1 throughout the CW portions of 40, 20, and 10 and is reasonably
resonant on 15. I can tune it with the KAT100 very easily for any band
including 80 and all the WARC bands.

I'm not an antenna guy, but I've gotta believe more signal is getting out of
this dipole than was with the multiband antenna that required traps, baluns,
and a tuner.

Craig
NZ0R
K1 #1966
K2/100 #4941

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[Steve Hostetler]

Leigh,
My doublets work great on the higher bands.  In theory, the lobe
configuration does changes with wavelength n of the wire, so you have
roughly 2n lobes.  But you also get some gain, and, more importantly, a
lower peak angle of radiation.  You can read all about it in W4RNL's
great write up:

http://www.cebik.com/wire/abd.html

73, steve, kx7r

Leigh L Klotz, Jr. wrote:

> What is the difference between the G5RV and the twinlead-fed 102'
> doublet with a current balun at the coax-to-balanced transition
> mentioned as an alternative?  Is it just the random length of twinlead
> rather than a calculated length?  Or is it a long run of coax vs. a
> short one?
>
> I know some people with G5RV's advocate a long coax run, but that just
> adds loss, so I kept mine as short as possible.  Mine works ok on the
> low bands, but poorly on 15m and up.  Wouldn't an 80m dipole be even
> worse, with many more strange lobes?
>
> Leigh / WA5ZNU
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[Stuart Rohre]

Certainly, traps and baluns "may" contribute some losses as well as loading
coils may.

Tune losses in a decent tuner are pretty low, unless you are trying to match
outside its design range.

There is no advantage save not having a reactance term to match out, to
having resonance on the antenna.

You will not get significantly more out of the resonant antenna, if the
reactance canceling means is high efficiency.  In other words you cannot
hear the difference between a resonant antenna and one near resonant.

See the writings of various antenna authors such as Cebik, Walt Maxwell, (in
Reflections) and others such as Bill Orr.

Stuart
K5KVH



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[Stuart Rohre]

The 80 m dipole feed with ladder line and a tuner can work well even with
multi lobes on the higher bands.

See any edition of the ARRL Antenna book or handbook for typical patterns,
or www.cebik.com antenna web site for patterns.  If you take into account
the lobe directions you will have fine results.

Just orient so that lobes are mainly in directions of ham populations on the
higher bands.

Stuart
K5KVH

[Ron D'Eau Claire-2]

The G5RV may work well, but I doubt if it'd work "better".

For most of my Ham "career" my mainstay antenna has been a doublet. That's a
center fed wire as long as I can make it (seldom over 150 feet since and
currently only about 50 feet) and as high as I can get it. It's fed with
open wire line using a balanced tuner.

The efficiency is excellent, even down to the band where it's only 1/4
wavelength long overall. At that extreme it's about 1 dB below a full-size
dipole. As always with a horizontal antenna, the big issue is height. For
best DX it needs to be about 1/2 wavelength above the ground: easy on 20
meters where that's about 32 feet, a bit harder on 40 where it's 64 feet and
pretty challenging for most ops on 80 where 1/2 wave off the ground means it
needs to be 130 feet high! That's why many ops who want to chase DX on 80 go
for a vertical. Less efficient on paper but still puts out more low angle
radiation than most of us can manage from a low horizontal antenna.

Of course, on those lower frequencies the horizontal is an excellent,
high-performing short-skip or "NVIS" antenna providing excellent signals out
to maybe 500 or even 1000 miles. My doublet at 30 feet has about 6 dB gain
"straight up" on 40. I've worked a few Japanese and Europeans on it on 40,
but most of my 40 meter contacts are in North America and my 80 meter
contacts show very good signals out to 600 miles or so. On 30 and 20 it's a
good DX performer that often gets me DX stations answering my CQ running my
K2/100 on CW. I couldn't help but smile to see that Mike, ZL1MH reported to
Kevin that I was one of the three stateside stations he could copy in New
Zealand during the ECN last Sunday afternoon on 20 meters.

The bottom line is that most of the "designs" that have become popular over
the years are simply variations on either the basic doublet that I use or
the basic "Marconi" antenna worked against ground. Some of them provide a
somewhat easier range of impedances for the ATU to handle, and others, like
the common center-fed 1/2 wave 'dipole' provide an easy match for cheap and
easy-to-handle coaxial feed lines, albeit only on the bands where they are
either 1/2 or 3/2 waves long.

Ron AC7AC

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