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Author Topic: G5RV vs Random Wire?  (Read 1674 times)
N2KGO
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Posts: 3




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« on: December 01, 2000, 05:22:30 PM »

I'm getting ready to purchase my first HF rig, and my thoughts have turned to antennas.....  I figure I have around 100' into the trees in my backyard to put up an antenna, and am expecting to anchor one end to the house and the other end to a tree. Am I better off getting a G5RV antenna, or using a random wire?

Either way I expect I'll be getting a tuner/transmatch. The G5RV is at least designed to be resonate on several ham frequencies. :-)  However, the end fed nature of the random wire means I don't have to run cable along/under the ground to the center of the antenna to feed it....

Bob N2KGO
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KI8DJ
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Posts: 188




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« Reply #1 on: December 01, 2000, 11:18:27 PM »

I would just put a ladderline feedline all the way up to the dipole less lossy than the g5rv and easier to tune length of wire is not that important.Also it will work well on 160 meters,not great but much better than g5rv.You will probably also be less prone to rf in the shack
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K3VO
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Posts: 28




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« Reply #2 on: December 02, 2000, 09:22:07 AM »

I agree about just running 450 ohm open wire direct to the ant. It can also be end fed if more convient but center is better.
The G5RV was, a nice ant for the seventies when rigs had pi-net works thus eliminating the need for a tuner.
It is no where as good a dipole with open wire. Those who want to know the truth about ants including the G5RV should buy Lew McCoys book avilable from CQ.
Ed
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N2KGO
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« Reply #3 on: December 02, 2000, 12:14:26 PM »

So your advice would be to put up a single band dipole, and use a tuner to operate it on the other bands?
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LA1SJA
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Posts: 55




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« Reply #4 on: December 02, 2000, 03:08:07 PM »

I suggest you put a dipole with a balanced laddder-line feeder.
Don't bother about the exact dimensions of the G5RV.
Tailor the length to your garden and your trees.
A dipole is a dipole. Some are resonant to half the wavelength you
operate at and some are not.
As you say, you will use a tuner anyway to make it multiband.
(Of all non-resonant dipoles, the specific dimensions of the wire,
the ladder-line and the coax feeder of the G5RV appears to be a
singularly akward choice, and has caused me everything from tuning
problems to BCI and TVI, depending on where it is put up.)
Any dipole length will do, but the actual length will affect the
frequencies for which it works best.
A dipole of two times 85 feet fed with a random length of ladder-line
is a fairly good compromise from 80m to 15m.
On good days it will do some work above these frequencies as well.
Two times 170 feet is great for 160 meters but tends to cut off the
higher frequencies.
Two times 43 feet is ok from 40m and up, and will work to some degree
on 80.
Running the ladder-line all the way into the balanced tuner is not
always practical. In that case, run a short length of coax from your tuner
to a 1:4 or 1:6 balun in your garden.
You need a fairly large balun to handle mismatches.
Consider spending some extra dollars on a good balun like the MFJ-912.
Burying the coax, or leaving it on the ground is the best, but
stringing it in the air above the height of people have worked as well.
A random wire may cause a lot of problems like RF in the shack,
equipment that is "hot" to touch and distorted microphone audio.
I addition you will have to provide some sort of ground plane or RF
counterpoise for it. Then there is the risk of picking up local noise where the
random wire is inferior to a dipole.
After all your struggle, you might end up with less contacts and less fun than
the ladder-fed dipole will give you.
Have fun.
73 de Svein, LA1SJA.
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KI8DJ
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Posts: 188




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« Reply #5 on: December 02, 2000, 03:31:22 PM »

I just had another thought about your antenna situation if you have a couple of trees spred a good distance apart away from the house you could feed a vee shaped antenna,laying on its side I've used these quite successfully. Also you could use a triangular loop,either antenna could be fed with a short run of 450 ohm or twinlead right at the corner near your house.1005/F in Mhz will give you a resonant length for a given freq. About 277ft. for 80 meter loop. Loops tune easily on even and odd harmonics and some people claim they are quiter than dipoles. sides need not be equal length.Hope this helps 73 Gary
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K4IA
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Posts: 66




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« Reply #6 on: December 02, 2000, 05:20:29 PM »

I had a G5RV --  sorry I wasted my time with it.  I now run a 160 meter shorty dipole (commercial product 82 feet - with loading coils about 2/3s the way out from the center) fed with ladder line.  It works great on all bands fed through an MFJ tuner.  Any dipole will work on all bands higher than it was designed for.  I went with the 160 meter shorty because I wanted that band too.  My ladder line goes straight down to the ground then snakes through the bushes on top of a wooden fence back to the shack - about 150 feet.  
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AC5UP
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Posts: 3822




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« Reply #7 on: December 02, 2000, 06:08:51 PM »

Four Words:

OFF-CENTER FED DIPOLE aka "COAXIAL WINDOM"

Works like a hose.
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K6XR
Member

Posts: 63




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« Reply #8 on: December 06, 2000, 10:06:30 PM »

I use a g5rv with a great deal of success. My next door neighbor (2houses down) uses a full size inv vee dipole at 60 feet and i use the gr5v at 40 ft. on 75 meters I consistantly best him by 3 db in all directions. I find the g5rv works good. I have used thed gap, carolina windom and settled on the g5rv. you should give a good look at the carolina windom at www.radioworks.com.  they have an array of good working antennas.
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KF4ZGZ
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Posts: 277


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« Reply #9 on: December 11, 2000, 02:58:31 PM »

You're thinking.....that shows promise!
First off, go with whatever fits. If you use ladder line and a tuner this wont be a problem. If you go with a dipole, make it as long as possible. The longer the better. G5RV? Mine was great, the only reason I replaced it was for a loop.( The G5RV blew my 80m dipole away!)
Random wire, FEEDBACK, also know as rf, would be the biggest concern ( thats why i never tried one).
Don't rule out a wire vertical. Approximately 35 ft tall with a couple of ground radials and you are in business. Add top-loading to get on 160m.( I have one that works.)
My favorite and my suggested antenna is a delta loop. If you have room for a G5RV you have room for a 80m loop. You see most with one corner up and two down to get vertical polarization, but I suggest you reverse this, this seems to work better. But most importantly of all.BUILD YOUR OWN!! You learn and have fun , and it makes troubleshooting antenna problems easier.Whatever antenna you chose, do the math, cut the wire, let the tuner do it's job. Dont be afraid to experiment, everyone who has replied has done so. Finally, remember that what works well in North Carolina may not work well in Alaska( or vice versa )
e-mail with questions...73 de Matt, KF4ZGZ

p.s.  Got room fer a 160m loop?
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