DPD OMNI X just set up

[737mech]

Sorry This VNA only to 900. Here's a few first pics. This is the initial screen after calibration of the VNA. Just adapted from N connector to the sma of the VNA. This is connected to the three foot rg-8 off the antenna. Remember this is the miltenna version not the original Omni X.

 

[ScanMaine]

I finally got my OMNI X antenna and got it all put together and set up. VERY good build quality. I couldn't get it up as high as I wanted, but it's only maybe 18" lower than my discone. And I really had no way to separate it further from the discone unfortunately. Out of antenna space. But the omni works pretty well. One thing is I am wondering if this antenna may be somewhat directional? I monitor a P25 simulcast system here in RI. I have been previously using a DPD 800 mhz mag mount up on roof. Reception was GREAT with the mag mount. But the place I mounted it right on a ground plane with a weight in it to keep it in place, is not really suitable. See picture. That metal plate is a computer side cover bent into shape with a section of 2x3 screwed into bottom so it stays put. So far even in the last wind storms it didnt move.
Anyway I want to take that off roof and use it mobile maybe. So the only thing I noticed differently with the omni x was the PROVIDENCE system isn't as strong as it was using the mag mount. I thought MAYBE the omni may have a SLIGHT directionality to it. MAYBE the discone is too close. All the other zones on P25 come in loud and clear full scale. I am going to go out and TURN slightly the omni to see if that makes any difference. Originally I planned to mount that discone in the CENTER PEAK part of roof but stupid ladder isn't tall enough. Wife doesn't mind antennas as long as they stay where they are. But nothing attached to house. And I didnt want to have coax run longer than 50'. I am also at my height limit with these mounts. Can go up any higher without GUYING and LONGER COAX. Well anyway I will try some very slight turn of the omni to see if that changes anything on the Providence zone signal.

How is your OmniX on the 800 to 900 side??

 

[Ubbe]

In the last picture you have a return loss of over 20dB at 765Mhz, that's really good and most commercial antennas doesn't do any better. Although they don't advertise the mil version to cover 700-900MHz it still looks to be useful there, or is it just acting as a dummy load? Have you tried comparing 750-900 to another antenna when doing listening tests?

/Ubbe

 

[737mech]

I am very happy with this antenna in the 800 band. I don’t have anything non-encrypted in 700. The 900 works great for DMR repeaters.

 

[compdude]

I am still trying to decide if the OmniX is better or worse than my Tram 1410 discone seems to be hit or miss. I have some VHF 118-125 that might have been better on the discone.

 

[bobruzzo]

I am still trying to decide if the OmniX is better or worse than my Tram 1410 discone seems to be hit or miss. I have some VHF 118-125 that might have been better on the discone.

Really difficult to tell. My Omni X is a little higher than my discone. Makes a difference on SOME freqs. But it could be because the Omni is higher. When I first got the Omni x it was same height as discone and I was comparing the two antennas. There was a slight increase in reception with Omni but since a discone has no gain, the design of the Omni may be better on certain freqs. Probablya more durable antenna than Tram tho.

 

[questnz]

I own both Onmi and D130, using with two-way switch. I get some static on Omni-X, but not on D130. Any reason for that. Bot at a similar height and about 5 meters apart. Feed by 5D-FB cable. Metal roof, metal poles.

 

[MDScanFan]

On all frequencies or just some? The D130 has a much broader bandwidth then the OmniX. The former covers around 100 to 1000 and the latter spans vhf, uhf air, and some upper uhf. Gains are about the same. If it’s a similar installation then I would venture to guess it it picking up more “noise” across its bandwidth that shows up at the front end of the scanner.

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I own both Onmi and D130, using with two-way switch. I get some static on Omni-X, but not on D130. Any reason for that. Bot at a similar height and about 5 meters apart. Feed by 5D-FB cable. Metal roof, metal poles.

 

[MDScanFan]

Sorry, I misread the message that the noise was higher on the OmniX than the discone. I don’t have a good explanation for that situation. One thing I have encountered is a loose connection at an antenna that caused higher noise than another nearby similar antenna.

On all frequencies or just some? The D130 has a much broader bandwidth then the OmniX. The former covers around 100 to 1000 and the latter spans vhf, uhf air, and some upper uhf. Gains are about the same. If it’s a similar installation then I would venture to guess it it picking up more “noise” across its bandwidth that shows up at the front end of the scanner.

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[bobruzzo]

Sorry, I misread the message that the noise was higher on the OmniX than the discone. I don’t have a good explanation for that situation. One thing I have encountered is a loose connection at an antenna that caused higher noise than another nearby similar antenna.

I suppose every situation is different. When I had my Omni x up at same height as my discone the differences were minor but I did notice UHF stations came in a little stronger with Omni. I ended up raising the omni up an extra 5' and use it for all conventional scanning vhf/uhf and at that height it performs very well. The discone was lowered a few feet and I use it for mainly some conventional P25 and milair/coast guard. But all in all I think from my observations and from the bands I listen to HEIGHT is the main thing...both antennas seem to receive similarly.