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Old 05-05-2013, 11:13 AM   #1
SoCalRVer
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Default New GP antenna, insulate from Mast?

I recently moved my radio shack from my motorhome into my house. I mounted a 4 foot piece of EMT pipe to a vent pipe on my roof and attached the antenna. The antenna is an Arrow GP 144/440. It looks like a J-pole with radials pointed down about 45 degrees. I used tie wraps to secure the RG-8X coax to the mast. My radio is a Yaesu FT-1900 mobile.
I am getting out fine to the local repeater which has perfect line of sight. Using the radio for simplex is interesting. I seem to be getting out fine except that when I check in on a Net, I am able to get a good signal from all except the Net Controller. He is about 5 miles southwest. Another station responding is another 2 miles away and also southwest. I can read him full quieting, great signal.
My question is, mounting the antenna to a metal mast that is probably grounded thru my sewer line causing me lose of signal? If so, how can I insulated it? Also, can turning the antenna with the J-pole section a certain direction help?
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Old 05-05-2013, 03:45 PM   #2
W5DOK
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I used PVC split in half to insulate mine. I was mounted on an inch and half pipe so I split a 2 inch piece of pvc and it works fine. The J pole may be a little directional, but probably not much. Wouldn't hurt to check it with a FS meter.
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Old 05-05-2013, 03:48 PM   #3
Andy N1ORK
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Usually the mounting of the antenna is at ground level because the ground for the coax is connected there. So, you should be ok on the vent pipe. The radials are also at ground, so there should be no problem there. Depending on what is between you, how much power you run and the net control 5 miles away may be an issue. I assume he is listening to you simplex on the input of the repeater. I don't think you should insulate it and turning the j-pole may not make any difference.
Post a photo so we can see what it looks like.
73 and good luck!
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Old 05-05-2013, 07:10 PM   #4
SoCalRVer
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Here are some photos of the antenna and pole. I spray painted the pole black.

As you can see it looks like a small J-pole.

Only running 50 watts at most. It's up about 20-25 feet off the ground. Coax runs across roof, under eaves, down exterior wall and under the house 3 feet.
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Old 05-05-2013, 08:37 PM   #5
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It's a ground-independent antenna, so insulating it from the mast, or not insulating it from the mast, ought to make exactly no difference at all.
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Old 05-05-2013, 08:54 PM   #6
SoCalRVer
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Can rotating the antenna improve signal?
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Old 05-06-2013, 05:07 AM   #7
Andy N1ORK
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Quote:
Originally Posted by SoCalRVer View Post
Can rotating the antenna improve signal?
It may, but may not be worth the trouble. I have an Arrow 2/440 j-Pole (without radials) and it makes no difference.
73
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Old 05-06-2013, 07:49 AM   #8
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Thanks Andy. We don't get much lightning here where I live and I'm some what low compared to other structures. Since the antenna is attached to the vent pipe going right thru the middle of my house, I should probably install some sort of lightning protection. Any suggestions? Something not too expensive please. I can't just throw the coax out the window and it goes under the house for 3 feet and comes up in a bedroom/office.
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Old 05-06-2013, 07:54 AM   #9
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I live in the mountains of western Maine and I can tell you terrain has a LOT to do with reception. One of our repeaters is about 6 air miles from my house and I can barely get into it with a hand held yet another one is in NH 15 miles away and I have no problem with that one. I am often accused of being off freq into a distant UHF repeater because of the multipath from the mountains.
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Old 12-13-2015, 10:22 AM   #10
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Probably a terrain issue. Rotating the antenna will probably make no difference it is an omni. Your best bet is more height.
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