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Trim antenna for 800?

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btlacer

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I have a new Radio Shack 20-176 scanner antenna. I want to listen to Evansville Indiana 800 Edacs system and this antenna is not good at all for 800. Can I trim the antenna to pick up 800 better? Which elements do I trim and how muxh should I trim off? Can I just trim one back or do I have to trim them all?
Thanks
 

FLRAILMAN

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This doesn't address the whole situation, however it may give you some direction until someone on the site who may have used this antenna before can advise you further, good luck.

Brian's Scanner Reviews

FLRAILMAN
 

N9WP

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Thanks for the link to my review, those are so old I forgot I had them out on the web..LOL. I have actually trimmed one of the UHF rods which are the 2 that stick up at an angle but it didn't improve a thing. I have 3 of the 20-176's up and was able to compaire them. Someone else might have gotten better results and like I said, I only trimmed one of them, not both and I didn't touch the VHF rod sticking straight up. The thing that will help you the most is the coax you use. I now run mine with LMR400 coax and that greatly improves the 800mhz reception on this antenna. The antenna is awsome at VHF though. It just doesn't shine on 800mhz but does ok.
 

SCPD

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I have a new Radio Shack 20-176 scanner antenna. I want to listen to Evansville Indiana 800 Edacs system and this antenna is not good at all for 800. Can I trim the antenna to pick up 800 better? Which elements do I trim and how muxh should I trim off? Can I just trim one back or do I have to trim them all?
Thanks
I have had 1 with my pro 197 since August, it's up about 24 ft& using cheap RG6 cable( 50ft) from walmart with more adapters that I really need but it does a decent job on the local EDacs system here. I pick up everything just fine ( 3 site system) works decnt on any band. Personally is goo antenna. I pickup a drive thru Fast food place about a mile down the road on UHF that I've never knew of befor I got it . Worth The $30.00 . I may upgrade mine later not sure. Oh & all I diid was put it togetehr & stick in the air.. I wouldn't go trimming unless you really need to.
Paul
 

conve36

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I was in your exact situation about a year ago. Except I wanted to improve UHF at a specific frequency. These are great antennas to play around with. I honestly have modified 4 of these in the past year, destroying almost all of them too. The thing is, is that you can cut the rods down but once you cut them too far, it trash. My problem is, I always think "Hmm, maybe if I cut this here down it will be better!" Although thats great thinking for experimenting, i gets expensive replacing antennas. Just remember that (in your case) cutting all the rods down to a 1/4 wave length for that freq (just over 3") would get you an ideal "ground-plane" antenna. Check out my video on youtube of my re-building of one of these.. YouTube - Radio Shack Groundplane VHF/UHF antenna project
 

conve36

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I get excellent results using RG-6 quad shield for scanning, and also do not seem to have any problems transmitting with low power on it as well. I would cut the 2 little vertical elements to 3 1/2" and leave the rest as they are. See what your results are. If you do not see any improvement, cut the 2 little ones off completely, filing them down smooth. Then cut the main vertical element to 3 1/2" as well as the ground elements.

For second thought. Go to radio shack and purchase the UHF chassis mount connector. Get your self a wire coat hanger, sand the metal on the coat hanger down to make sure you take off any coating on it. Then solder or bolt the elements (all 3 1/2") to the connector. You would HAVE to solder the vertical element though. You then have yourself a great 800Mhz ground-plane antenna. For like $4!
 

SCPD

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Back to the topic (sort of).

I have a question kind of related to the first posting in this topic, trimming antennas.

What would be the least expensive way to check the match on a homebrew beam for 900 mhz?
 

DPD1

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The problem is, there's no affordable analyzers above 400 MHz or so. So when you start getting up in that area, you have to use a commercial analyzer, and those are very expensive, even just to rent. If you're allowed to transmit on the device in question, you could possibly just use a meter. But for that area, that's still going to be tricky to get hold of unless you know somebody that has one.
 
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