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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Ampro 80 metre vertical magmount - ground plane wires?
Would it be sensible to use ground plane wires on a car mounted magmount 80 metre vertical base-loaded ampro? It is a 3/8" stud fitting, so presumably any groundplane wires would either need to originate from the magmount base or the rig itself. I'm entirely confused whether this is a good idea or not?

The alternative would be a tripod mount with groundplane wires - this would be easier for me to accomplish, although I think both suffer from a lack of height (is the rule a minimum of 1/4 wavelength above ground?)

Someone please enlighten me!

Many thanks, Mark.
M6VMS

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Tue Jan 03, 2017 3:33 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
Mark, Do you mean to use the antenna while mobile, static mobile, i.e parked, or some other use?
If you are going to use it mobile, a hole drilled through the centre of the roof, and fitted with a suitable mount will beat any other method.


Tue Jan 03, 2017 5:35 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
Some initial investigation online garnered the following from http://www.icarc.org/antenna_myths%5B1%5D.pdf:

WHERE you mount your HF mobile antenna is “almost” as important as WHICH antenna you use.

• Remember, you are building an antenna system, it is not just the antenna alone. Bonding, coax, matching, capacity hat or not, mounting location and method of mounting are all part of that system.

• Antennas mounted close to the road, like bumper or hitch mounts, have greater ground losses than those mounted on top of the vehicle roof.

• Loading coils MUST be kept as far away from the metal vehicle body as possible.

• Magnetic or “mag mounts” do not properly couple the shield of your coax to the vehicle body. The vehicle body is the other half of your antenna and only minimal capacitive coupling to the body occurs with a mag mount. Your coax shield needs to be “solidly connected” to the vehicle body.

For those of you who are still unclear, I will restate it.
NEVER use mag mounts for an HF mobile antenna.

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Tue Jan 03, 2017 5:35 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
Static use only, and drilling holes or attaching brackets isn't an option, so if mag-mount or some combination of mag-mount and ground planes isn't an option then I'd have to resort to a tripod based antenna.

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Tue Jan 03, 2017 5:36 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
Mag mount is the worst possible option and on the lower frequencies it will be even worse common mode all over the place very poor efficiency think how far you will get when only 1% or less of your allowed 10 watts get radiated

parking up and chucking a dipole along a hedge will work better

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Tue Jan 03, 2017 6:29 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
OK, so ruling out a mag mount at the moment, it would appear that an experiment with the 80 metre ampro, mounted close to the ground on the tripod (the legs can be splayed to the get base of the antenna within about 30 cms of the ground) and then employing a set of 16 radials around the same physical length as the antenna may be the first option to try.

I read the following articles to determine this may be the way:

http://www.chem.hawaii.edu/uham/radials.html

http://wa3wsj.homestead.com/W2FMIVertTests.pdf

http://www.astrosurf.com/luxorion/Radio/qex-ground-systems-part-4.pdf

http://www.astrosurf.com/luxorion/qsl-radials.htm

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Tue Jan 03, 2017 8:05 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
I would try a pair of 80 metre hamsticks joine by a centre connector as well
http://www.sandpiperaerials.com/product ... iguration/

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Neill
Its not the class of licence the amateur holds thats important but the class of bias the prat applies to his amplifier


Tue Jan 03, 2017 9:08 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
Thanks for the suggestion.

Would operating as a 'V' dipole negate the need for a ground plane?

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Tue Jan 03, 2017 9:14 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
M6VMS wrote:
Thanks for the suggestion.

Would operating as a 'V' dipole negate the need for a ground plane?


:) Yes it would as a dipole is a balanced antenna

A V dipole can be supported by a non conductive telescopic pole such as a flagpole this can be mounted into a simple 'ground screw' of the type used for rotary washing lines. The two dipole legs once attached to some non conductive nylon cord/rope will act as guy ropes.

Loads of people use this system some useful information here
http://patternila.info/inverted-v-pattern/

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Tue Jan 03, 2017 9:32 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
M0RDI wrote:
M6VMS wrote:
Thanks for the suggestion.

Would operating as a 'V' dipole negate the need for a ground plane?


:) Yes it would as a dipole is a balanced antenna

A V dipole can be supported by a non conductive telescopic pole such as a flagpole this can be mounted into a simple 'ground screw' of the type used for rotary washing lines. The two dipole legs once attached to some non conductive nylon cord/rope will act as guy ropes.

Loads of people use this system some useful information here
http://patternila.info/inverted-v-pattern/

What he said :)

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Neill
Its not the class of licence the amateur holds thats important but the class of bias the prat applies to his amplifier


Tue Jan 03, 2017 9:47 pm
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
If I create a V dipole antenna will I need a balun to connect it to COAX?
If so, would that be a 1:1 balun?

Thanks for the help, Mark.

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Wed Jan 11, 2017 10:05 am
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
M6VMS wrote:
If I create a V dipole antenna will I need a balun to connect it to COAX?
If so, would that be a 1:1 balun?

Thanks for the help, Mark.


Balun optional, but nice.

Yes, if you do use one, then 1:1.

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Wed Jan 11, 2017 11:30 am
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
Would one of these work? I can build one of these for around £5.

https://www.nonstopsystems.com/radio/pdf-ant/baluns-portable_w2du.pdf

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Wed Jan 11, 2017 11:36 am
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
M6VMS wrote:
Would one of these work? I can build one of these for around £5.

https://www.nonstopsystems.com/radio/pdf-ant/baluns-portable_w2du.pdf


Looks OK, but you can buy them ready-made in a weatherproof box for peanuts.

Get a 100W one to future-proof yourself. :)

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Wed Jan 11, 2017 11:39 am
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 Ampro 80 metre vertical magmount - ground plane wires? 
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Post Re: Ampro 80 metre vertical magmount - ground plane wires?
Sorry to say at the moment I've got no idea what I'm looking for - any chance of a link or two?

Many thanks for all the info and advice.

Mark.

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Wed Jan 11, 2017 12:22 pm
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