Antenna vehicle positioning

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af5rn

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Problem is, that antenna comes with only 9 feet of coax, so the trunk lid is not an option for many, unless you just string the coax straight to the front seat like a clothesline.

People here swear by that antenna. I just ordered one myself to experiment with, just for grins (along with several others). I'm interested to see how it stacks up, because it's a very attractive option for those going for the stealthy look.

Obviously, as previously mentioned, centre of the roof is always the best plan. Any variation will affect your radiation pattern, however that may or may not make any real difference for you if you are not listening to weak, fringe systems.

If not going for the centre, at least try and put it at least eighteen inches from the edge of the roof to give you a decent measure of omni ground plane.

Let us know how it works for you!
 

NorthCOVideo

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Its a van so I'm thinking I'm going to put in the center of the roof or as close as I can get it and run the cable down the door frame to hide it and to my scanner.
 

senduhelp

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I have that antenna. It works relatively well for its size. It doesn't work well at all for low band coverage but it's not supposed to. My advice would be to every now and then tighten the whip of the antenna. I almost lost mine because I guess the force of the wind causes it to unscrew from the base over time.
 

NorthCOVideo

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Thats great to hear that many have them, I'm going to be using it mostly for UHF-800Mhz coverage. And thanks for the advice I'll have to remember to keep an eye on or find a way to keep it tight.
 

SAR923

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Assuming that's really a Valor made antenna and not a cheap knockoff, you should be very happy with the performance from about 150 MHz on up. Unless you're next to the tower, don't expect anything from low band and it's marginal on the civil air band.

I had a problem with cable routing and the supplied cable not being long enugh. I got 10 feet of RG-58 and put a female BNC on one and and a male BNC on the other. That gave me enough length that I could put the antenna in the center of the roof. I'm sure there was insertion loss from the added connectors but I think it was more than overcome by the good ground plane provided by the roof.
 

stevolene

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I have both the valor pmm3 and the workman KS3, there is no difference between the two of them in performance or the way thier made, the 9ft coax is the downside, I have a crown vic, I had to use another peice of coax and join it together to make it from trunk to dash, I, well aware that this somehow must be creating a signal loss, however I cant hear the difference, also transmits well on 2 meter
 

NorthCOVideo

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Got mine 30mins ago and got it installed, its a nice little antenna, seams to work really good.

Had to mount it closer to the side to get more cable, still barely enough, might need to figure out how to change it out with a longer piece, maybe splice it and solder in a longer section.
 
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af5rn

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Yeah, the coax is the major drawback to that antenna. It's crap coax and it's too short to be of use for anything other than a very temporary install. It might be good for throwing on top of your file cabinet at work or something, but not really for a car. Considering how well the antenna performs with those shortcomings, I can only imagine how great it could be with decent coax. Personally, I wouldn't try and replace any coax. You only risk screwing it up. I'd just plug it into a multicoupler or amplifier and then add the extra coax I need to the other side of that.
 

n5ims

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Splicing coax - just say no!

Had to mount it closer to the side to get more cable, still barely enough, might need to figure out how to change it out with a longer piece, maybe splice it and solder in a longer section.
Please be aware that the quickest way to ruin an antenna system is to splice coax. If you must extend the length of coax, use a barrel splice and connectors. Simply soldering on more coax will cause nothing but grief. While it can be done in extreme emergencies, the impedance mismatch and gaps in the shield will do more harm than good. RG-174 is quite difficult to work with since it’s so tiny and will only compound the problem.

Your best bet would to get some RG-58 with a female BNC on one end and male on the other. Your other option would be to get one with male BNC connectors on both ends and a barrell splice to join the two pieces of coax such as this one from Radio Shack
http://www.radioshack.com/product/i...&cp=2032058.2032231.2032281&parentPage=family
 

jon_k

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Personally, I wouldn't try and replace any coax. You only risk screwing it up. I'd just plug it into a multicoupler or amplifier and then add the extra coax I need to the other side of that.
It's not so hard. Just don't short out anything and your new coax works great, Already done this with NMO mounts. I totally replaced the coax on the backside of the NMO mount to my radio.

I don't think I'd ever splice coax though. I would get a converter to extend the cable. It would be like splicing Ethernet cable. I'm sure you would introduce losses in the line. I'm sure SWR would go up bigtime during transmit.
 
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SAR923

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That antenna doesn't look right at all, especially if it's supposed to be a Valor. Look at the picture of mine compared to yours. You should have three tight coils on the bottom with the small insulator section between them and the top coils. If the packaging said this was a Valor antenna, I'd send it back for replacement. If it doesn't mention anything about being a Valor, I think you got ripped off.

Valor Antenna (Medium).JPG
 

af5rn

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The eBay auction he got it from never says Valor. It calls it a "TMM3" instead of a pmm3 too.

The description says it is 17 inches tall, which is 3.5 inches taller than the Valor.

I've heard that multiple manufcturers are selling a similar antenna, so this must be one of them. Was there a brand name on the packaging, osoklrs?
 

SAR923

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Agreed, which is why I posted my original message about it possibly being a Valor ripoff. By the looks of it, they didn't even make a very good try. A real Valor is not much more than he paid for this knockoff and I'll bet it would do a lot better job too. This thing looks like a twisted up 1/4 wave VHF antenna
 
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The eBay auction he got it from never says Valor. It calls it a "TMM3" instead of a pmm3 too.

The description says it is 17 inches tall, which is 3.5 inches taller than the Valor.

I've heard that multiple manufcturers are selling a similar antenna, so this must be one of them. Was there a brand name on the packaging, osoklrs?
I was just noticing that too. Mine i got from Ham Radio Outlet years ago and it is like the TMM3 with the longer more stretched out coils. SWR is a good match at 163mhz not 2meters and the performance isn't that great I think. Not any different then a plain 1/4 wave whip for VHF-Hi. another thing was when i ordered mine the photo in the catalog looks more like the other one with the tighter coils so i wonder if they had both under the same catalog number or subsituted.

eric burris
 
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