Multiple Scanners sharing 1 antenna

General questions on scanning from 30 to 3000Mhz. Not sure what you can receive in your area? Here's the place to ask!

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numloxx
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Multiple Scanners sharing 1 antenna

Post by numloxx » Fri May 22, 2015 11:52 pm

Hi all,

I want to add 2 or 3 more scanners to my LiveATC feed.

Currently I have an old Uniden 3000XLT (From memory), connected to a raspberry pi. Antenna is along a RG58 (or 59) coaxial cable about 15-20 m in length to my friend's apartment balcony which has line of sight to the airport tower and some of the field.

What kind of rf performance loss will I get if I had 2 or 3 extra scanners to that cable, so that I can provide feeds for 3 or 4 different channels separately?
Is it better to have a max of 2 scanners per antenna? Upgrade cable to RG6 or RG216 or something heavier?

The plan is to have a separate feed for MEL CTR, APP, TOWER/GRND and Departures (or Delivery) instead of scanning all the time between them all.

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Re: Multiple Scanners sharing 1 antenna

Post by yorky » Sat May 23, 2015 10:56 am

I run two off one without much drama, but I'm sure others can chime in with actual losses.

Shouldn't hurt to just give it a shot, I know you can run several TV's off one antenna also without a lot of drama if you have good reception. So if it is line of sight to the transmitter it should be fine.
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Re: Multiple Scanners sharing 1 antenna

Post by Bonez » Sat May 23, 2015 11:22 pm

It should be fine to add more receivers, but if it were me I would think about upgrading that RG58 to RG213 if you have the opportunity to do so.
You'll naturally get a bit of loss through the additional connectors and patch cables needed to connect those additional receivers, so with better quality coax you'll eliminate some of the losses incurred with that.

In saying all of the above, if you have line of sight to the airport in that particular location, it probably won't make a huge amount of difference if you are only trying to receive air traffic anyway.

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Re: Multiple Scanners sharing 1 antenna

Post by numloxx » Sun May 24, 2015 11:08 am

Hi Bonez,

Yeah I intend to upgrade the cable to RG213 soon, due to the extra signal required to split it 3 ways initially, and later on 4 ways.

Thanks for your advice.

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Re: Multiple Scanners sharing 1 antenna

Post by vk6hgr » Mon May 25, 2015 1:48 pm

I'd use TV RG6 and a TV-type splitter for your scanners. Crimp and F-type adapters are available to go to PL-259 and BNC. The impedance mismatch loss loss of RG6 over that length of a run will be less than the loss of using 50ohm cable, and splitters are far cheaper.
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numloxx
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Re: Multiple Scanners sharing 1 antenna

Post by numloxx » Mon May 25, 2015 9:47 pm

Hi Gav,

I got a friend of mine to get me some LMR400 cheap, 25m length. At the end I've 3 x t pieces.
Reception with 3 receivers is nearly better than before with the RG58.

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Re: Multiple Scanners sharing 1 antenna

Post by interference » Mon Aug 24, 2015 10:11 pm

I use RTL-SDRs to receive and share ADSB data. I have just ordered a TV antenna amplifier splitter as I have 4 RTL SDR dongles running from one antenna and I think they would be better served with a proper splitter / amp. I will advise of results. Anyone else tried it?

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