[Antennas] need advice on using my G5RV on 160m

Sat Apr 30 17:08:31 EDT 2005

I've used a 75 meter dipole with both legs of the ladder line tied 
together and worked against the station ground on 160 much as you might 
feed a long wire. It tunes easily with an MFJ969 and another "tee" type 
tuner I have available. Reports are decent at the 100 watt level and no 
RF problems in the shack.
Continuing this configuration up to 75 and 40 meters also works okay at 
100 watts; however, starting around 20 meters and up the length of 
ground wire (from the tuner to the soil) becomes a problem and RF in the 
shack becomes noticeable.
My ground is primarily for lightning protection and is three ground rods 
spaced over 30 feet around the house perimeter and includes the house 
ground and ties several antenna masts (TV yagi, 2 meter GP, etc) together.
I would think a counterpoise would help especially if the safety 
grounding was poor at RF, but it might be hard to know how much 
improvement to expect.
You need a good "earth" ground for safety reasons so I'd start with that.
Pat
wa4tuk
RB wrote:
> I am using the MFJ G5RV, and have a coil of coax for balun purposes between
> the ladderline and coax to the shack. My G5RV works fine.
>> Now, I'm starting to think about using it on 160m, as the MFJ instructions
> say I should be able to do---with a bit of monkeying around.
>> MFJ says the G5RV, when configured as a single wire fed horizontal antenna,
> acts a Marconi type of top loaded vertical.
>> Specifically, the instructions give me two options for 160M use. One is to
> feed one side of the coax at my shack with a single wire to the tuner, and
> ground the other side of the coax to a good earth ground or counterpoise. I
> have no idea what this becomes in this mode.
>> The other option is to connect the coax outer conductor to the inner one,
> and feed both with a single wire from the tuner, using a good earth ground
> or counterpoise to the rig.
>> A question is what the consensus is as to which of the above feeds would be
> the better?
>> I could remove the balun, and then feed one side of the antenna hot, with
> the other side going to ground and/or counterpoise. Again, what would this
> be?
>> The other question is whether or not I'd be better off with two long (maybe
> 100') counterpoise runs in opposite directions, as opposed to a good earth
> ground only?
>> Help appreciated.
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