i have a mag mount uhf ant and a Diamond W9NES base ant. i am trying to hit a gmrs repeater and the mag mount keys it up and it is clear most of the time could be a little better. when i hook the diamond up i cant not key up the repeater at all. any suggestions to why the mag mount is better then the base ?
Mag mount vs base
- Thread starter kb1oar
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DPD1
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If you're in your car in the driveway and the mobile brings it up but not the base on the roof... then it sounds like there's a problem in the line of the base one somewhere. This is assuming that the antenna isn't being blocked or something. If it's higher than the car though, it should be OK. GMRS is a high enough band that you might get 'on-off' type fading if you're in a spot that happens to be if-y. If that's the case, moving the base antenna around a little might have totally different results. But I would check and make sure there's no faults in the line.
Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist
Dave
www.DPDProductions.com
Antennas & Accessories for the RF Professional & Radio Hobbyist
I'm not sure what a 'Diamond W9NES' antenna is - that's not a normal part number for Diamond. So I'll make an assumption - is it a dual-band fiberglass amateur band vertical? If so, some of those are quite narrow-banded. I have a couple that go deaf very shortly after getting outside the ham bands, and GMRS is going to be a ways outside that band!
Further, even if it'll go that far if it's tuned for amateur bands, the SWR at GMRS frequencies is going to be quite high. Your transceiver may be "folding back" and putting out very little power, due to the SWR. (I just swept one of mine with an antenna analyzer, and it's around 3:1 in the GMRS range.)
If I'm not right about the type of antenna, then just ignore me...
Further, even if it'll go that far if it's tuned for amateur bands, the SWR at GMRS frequencies is going to be quite high. Your transceiver may be "folding back" and putting out very little power, due to the SWR. (I just swept one of mine with an antenna analyzer, and it's around 3:1 in the GMRS range.)
If I'm not right about the type of antenna, then just ignore me...
Well, in that case the antenna I ran the analyzer on is the same one. So your GMRS radio is probably seeing something around 3:1 SWR when transmitting. Most current ham gear folds way back to save the finals in that case, not sure about a GMRS radio, although I would suspect the same.
I don't think you can actually tune these antennas, other than cutting elements - and I'm not sure that would be too easy. This antenna is three 5/8-wave stacked so you'd have to trim each of the 5/8 sections to the right length, probably by cutting and resoldering the elements - the joints probably aren't in the right places. (And it would no longer work well on ham bands, 2M or 440.)
Your best bet would be to get a separate commercial-band base antenna for GMRS. You could by one from a variety of vendors, but if you are up to building, there are plans out there for all kinds of amateur band antennas. You would just need to recalculate the lengths for the higher frequency. Then you would have an antenna tuned specifically for the frequencies of interest. (My first inclination would be a J-pole, as I've had lots of practice making those out of 1/2" copper pipe and they hold up well outdoors.)
I don't think you can actually tune these antennas, other than cutting elements - and I'm not sure that would be too easy. This antenna is three 5/8-wave stacked so you'd have to trim each of the 5/8 sections to the right length, probably by cutting and resoldering the elements - the joints probably aren't in the right places. (And it would no longer work well on ham bands, 2M or 440.)
Your best bet would be to get a separate commercial-band base antenna for GMRS. You could by one from a variety of vendors, but if you are up to building, there are plans out there for all kinds of amateur band antennas. You would just need to recalculate the lengths for the higher frequency. Then you would have an antenna tuned specifically for the frequencies of interest. (My first inclination would be a J-pole, as I've had lots of practice making those out of 1/2" copper pipe and they hold up well outdoors.)
as i posted this a few times already the last 2 weeks in this forum..... Arrow Antennas has Jpoles for many different freq ranges besides ham radio. http://www.arrowantennas.com/kb1oar said:
also almost forgot this one: http://www.antennawarehouse.com/VHF-UHF/VHF_UHF_index.htm
Eric burris kc0ldt
"I don't think you can actually tune these antennas, other than cutting elements..."
You can't and you can't do that either. It's a phased collinear vertical array consisting of a brass wire coiled in places (the phasing helical delay lines) inside a PVC tube. Cutting any part of it would be disastrous.
Looks to me the Part # AWH-450 from Antenna Warehouse is the better deal.
You can't and you can't do that either. It's a phased collinear vertical array consisting of a brass wire coiled in places (the phasing helical delay lines) inside a PVC tube. Cutting any part of it would be disastrous.
Looks to me the Part # AWH-450 from Antenna Warehouse is the better deal.
N1BHH
Member
If your X510 is fed with RG8U there is inherent loss in the feedline. Use 9913 or LMR400 and it will work better. I know a guy who has the same antenna an hits our GMRS machine from 20 miles away. Now if your using a hand held at home and a 25-50 watt radio from the car, there is the difference.
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