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[TowerTalk] G5RV

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Subject: [TowerTalk] G5RV
From: (Bill Coleman AA4LR)
Date: Fri, 25 Apr 97 11:37:20 -0400
On 4/1/97 12:17 PM, Carlos Augusto S. Pereira at wrote:

>I will raise a a tribander beam for 10-15-20 however for 40/80 I am still
>thinking about. Some US hams have pointed the G5RV as a good solution but
>there is a necessity of a 32ft tower, isn't it? 

Rather than a G5RV, I suggest you put up a simple doublet (dipole) fed 
with tuned feeders (open wire or twin lead). It will have as good as 
performance as the G5RV.

The G5RV isn't magical. It is merely an extended double zepp for 20m fed 
with an appropriate matching section. The only band it is resonant on is 
20m. It just happens to be easy to tune for other bands. A doublet (of 
any length) with tuned feeders (of any length) is a simpler and better 

>My questions are: 
>1) Will the G5RV cover 40/80 meters with a reasonable performane? Does it
>require a standard Antenna Tunner?

Yes, the G5RV will require an Antenna Tuner, especially with today's 
solid state rigs that fold power back at SWR higher than 1.5 or so.

>2) To raise it 10 meters up is a must? It doesn't work lower? There is a
>limitation of 5 meters over the building's roof.

The single most important dimension in a horizontal antenna (ie dipole) 
is height above ground. (At least for heights less than a wavelength or 
two - that's 80-160m!)

The answer is to put it up as high as you can. It will work lower, just 
not quite as well. I'm using a 125 foot doublet that's only 10-15 feet 
off the ground right now.

>3) Does it work in an inverted V configuration?

Yes, but a simple doublet works just as well.

>4) Van Gorden manufactures one like that with a transformer. Is it good?

The transformer is ok, if you have to run coax. However, since the 
antenna is non-resonant, you'll have higher losses in the coax.

Open wire has less loss, but is troublesome to bring into a building. For 
years I've run transmitting twin-lead to the house, then switched to a 
balun with a short run of coax to the shack. Use only solid dielectric 
coax (RG-8)! Sure, foam dielectric has lower losses, but substantial 
voltages can be present in the coax in this "unmatched" configuration. 

Bill Coleman, AA4LR, PP-ASEL        Mail:
Quote: "Not in a thousand years will man ever fly!"
            -- Wilbur Wright, 1901

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