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Scanner / Receiver Antennas For discussion of any type of receiving antenna used by a scanner or receiver base, mobile or handheld.

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Old 06-07-2012, 1:29 AM
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Default Diamond Discone or Omni X

I want to buy a new antenna because I am not happy with the performance of my Scantenna. I am thinking of buying either the Diamond Discone with the N Connector or an Omni X. I monitor VHF Low 33.70 to be exact because some of the counties around me are still using it. My home county is on UHF. I have no need for VHF High or 800. The antenna will be outside on a 20' mast and will be fed with 30' of LMR 400. Will the Omni X do VHF Low? If not I guess it would be wiser to go with the Discone? Any help would be appreciated.
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Old 06-07-2012, 3:23 AM
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The Diamond Discone antenna would probably do better than the Omni X, simply because it's designed to cover the 33.7 Mhz frequency range (has that long top element). Would it perform better than the antenna you are using now? Beats me, but maybe.
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Old 06-07-2012, 5:15 AM
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Wow, I'm surprised 30Mhz is still used in the States! It must be horribly noisy in town.

Anyway, I have the Diamond D-130J discone and have done some testing on it. The antenna works relatively well on frequencies from about 100Mhz up to 1.3Ghz (Low VSWR and -3 to unity gain). However, the discone elements are not long enough on their own for frequencies below about 100Mhz. The top vertical element is actually a loaded 6m (50Mhz) resonator, which provides a reasonably low VSWR on a very narrow band (about 1Mhz wide) on 50Mhz. I have put a return loss bridge and a sweep generator on the antenna and it does offer low VSWR on most frequencies above 100Mhz. Below 50Mhz though, the antenna works about as efficiently a piece of wet string.. On 30Mhz you won't hear much at all with the D130j, unless it is a strong signal already..

You could try one of these:

http://www.cometantenna.com/pdfs/UHV-4_manual.pdf

Gives you all the bands you are interested in..
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Old 06-07-2012, 5:31 AM
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Even the Omni X isn't going to do well with low band,it's design is 118 and above.
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Old 06-07-2012, 6:34 AM
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I'm surprised the Scantenna didn't perform well. I always had good look with them even down into low band.
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Old 06-07-2012, 7:55 AM
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Maybe there is something wrong with his Scantenna or coax?
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Old 06-07-2012, 12:00 PM
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I don't think you will find a discone design to perform better than a ST2 on Lo Band. I have used both, Discone and Dipole design.My old 5094A Channel Master and ST2 have performed the best in that range. Like Rt169Radio mentioned you might want to do some investigation on the antenna and coax.
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Old 06-07-2012, 1:40 PM
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I may have done something wrong with the Scantenna. I just thought I should have been picking up more of Westmoreland County which is on 33.70 better than what I was. I used the RG6 that came with the antenna as far as the coax goes but I plan on upgrading to LMR 400.
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Old 06-07-2012, 2:16 PM
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Quote:
Originally Posted by Tom_Pa View Post
I want to buy a new antenna because I am not happy with the performance of my Scantenna.
Doublecheck the balun, or perhaps try a replacement like the RS #15-1140. The baluns shouldn't be too lossy at vhf low, so maybe yours is just kaput. For UHF / 800 mhz, some might want to try several higher-quality baluns with less loss - the tv forum guys seem to prefer blonder-tongue, channel master, etc....
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Old 06-07-2012, 7:09 PM
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I have a d130j on the roof that pulls in the CHP in the 42megs from all over the bay area. I cannot figure out where exactly the transmitter sites are, but from western San Francisco, I can hear San Mateo County, Marin, Alameda, Hayward, Santa Rosa, and even Fairfield out 60 miles. All different signal strengths too. I think that's pretty good for vhf low.

EDIT-I did a couple videos just wanted to show that the d130j isn't such a "wet noodle" on vhf lo IMO

the CHP in SF, Redwood City, Hayward, Oakland and Marin
http://www.youtube.com/watch?v=ZRPZQYDvs5E

some park rangers out in the east bay
http://www.youtube.com/watch?v=L0BG46C6Vus
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Last edited by ridgescan; 06-07-2012 at 7:49 PM..
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