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Mounting A Mobile Antenna On A Mast

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Old 07-21-2009, 08:24 AM
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Question Mounting A Mobile Antenna On A Mast


Over the weekend I stumbled across a Yaesu 8900R and Comet UHV-4 antenna for sale locally on Craigslist. It was a good price so I bought it. The seller demonstrated it working and everything, but he had it mounted in his car. But I want to run this in my house as my commute to work is very short and I will get more use out of it in my house. I know its not the ideal antenna for mounting at home, but free is about as cheap as it gets.

So here is my question: If I mount this antenna on a mast behind my house, do I need to isolate the antenna mount from the mast? Also, does any part of the antenna need to be grounded to work?

Sorry if this question has already been answered. I have been googling since Sunday and have not found exactly what I am looking for. Thanks in advance for your help.


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Old 07-21-2009, 09:00 AM
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You could call some ham radio stores and ask about a radial kit for the UHV-4.
google found a post mentioning the radial kit, so it may be available.

If not, then you may just want to leave that antenna for mobile use, and buy a different base antenna from diamond or whatever. That radio does 6m and 10m, but is of limited use there since its only FM.

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Old 07-21-2009, 09:23 AM
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Eventually, you might want to consider a trus base antenna.

Diamond® Antenna ~ V2000A Tri-band Base Antenna

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Old 07-21-2009, 11:11 AM
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You might experiment with four radials, each about 20" long, attached right at the feedpoint.
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Old 07-21-2009, 12:26 PM
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Can that antenna be used as a base/fixed antenna on a mast? Yes it can, if you make an addition or two to it. Very simply, you have to supply the part that the antenna expects to see when used on a vehicle, the other half of it, the counterpoise, groundplane.
(I hate that word, 'groundplane', it's misused a lot. But in this case, it's exactly what's needed.)
Like with most multiband antennas that require a groundplane, if you furnish a groundplane sized for the lowest band of use, the higher bands just use what they need and don't worry about the 'extra'. So, if you plan to use 10 meters, the lowest band for that 'Comet UHV-4', then that's the size of radial(s) I'd put under the antenna. Not gonna use 10, just down to 6 meters? Fine, do 6 meter radial(s) instead. Or just 2 meters isw that's all you want to use.
So what size should these radials be? Good question, I can't answer that cuz I don't have one. They should be a minimum of the same length as the antenna, plus a little more probably. Lot's of 'skootch' room there, use whatever works for you.
How well will it work? Can't say for sure, but it ought to work as well as if it were on a vehicle. Probably a bit better cuz it's higher (don't expect miracles ).
That antenna has to be one of the best you could have! Why? Cuz it was 'free', naturally! I tend toward 'Comet' VHF/UHF antennas if I can, I've had good experience with them on mobiles. That certainly doesn't mean very much, I haven't tried them all, so take it for what it's worth. Also found one or two that were a PITA, mainly because they were a bit 'more' antenna than I thought they were (hit a tree limb, knocks down tree limb, that sort of thing, weird huh?).
- 'Doc

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Old 07-21-2009, 12:48 PM
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Thanks for the replies. What materials could I use for a 'ground plane'? I assume I need about 4 radials the full lenght of the antenna (52")?

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Old 07-21-2009, 12:58 PM
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Radials.
You would need at least one. More doesn't hurt till it gets really ridiculous. What to make them out of? Well, as long as it will conduct electricity, whatever it is ought'a work just fine. No particular size, etc. Whatever you got that will 'do' it, sort of. Going to use guys on that mast? Use them. Or just wire strung up with twine? Or, weldin rods 'tacked' together to get the length? Coat hanger work too. You're only limited by your imagination (and neighbors sometimes?).
It's something you have to experiment with, but longer is better than shorter.
- 'Doc

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Old 07-21-2009, 02:23 PM
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Thank you. That gives me a direction to go. I am going to put up a mast behind my house. I plan to get 20 feet of 1 1/4" galvanized steel pipe and bury about 4 to 5 feet of it in concrete. The first 6 feet above ground I plan to tie into my deck. The antenna on top of that should be about the height of my house. If not, I will add another piece of pipe . I figure as long as its not real visible from the street I won't catch too much grief from neighbors.

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