Author Topic: Wiring for Scanner Antenna  (Read 1674 times)

MP 225 on the CR Indy Line

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Wiring for Scanner Antenna
« on: October 27, 2013, 07:43:51 PM »
I'm in the process of rewiring several rooms in my house I gutted completely.  Previously, I had a simple antenna connected to my Radio Shack handheld scanner with a stock cable.  However, when I had my house re-sided last fall, my aerial was removed and not replaced.  I'd purchased this scanner before they were banned in one's automobile for people without a HAM radio license.

I'm thinking of placing an antenna for my scanner in my attic on or near an exterior wall.  The antenna would be about 10' lower than my previous exterior antenna, but it would be about 8' higher than if I had no antenna at all.  Has anybody else had luck with an antenna placed in one's attic?  With the exterior antenna, my reception was MUCH better than without any antenna.  I'm just not sure whether that had to do with its height, its outside placement, or both.

I'm also thinking about having a splitter in the attic so that I can have a cable feed to both my bedroom and living room.  This would allow me to use the scanner (with the antenna) in either room instead of being limited to just a single location. 

I've found a few on-line references (e.g. RadioReference.com), but I'm interested in hearing the opinions of some local people. 
Brad
MP 225 on the CR Indy Line

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Re: Wiring for Scanner Antenna
« Reply #1 on: October 27, 2013, 08:38:05 PM »
Adding a splitter will reduce your signal somewhat.
You are best to get it outside if possible, that said an attic mounted antenna will work.

but you didn't have any foil backed insulation put on before they redid the siding did you? 

If you did, then you will have to get the antenna outside.

MP 225 on the CR Indy Line

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Re: Wiring for Scanner Antenna
« Reply #2 on: October 27, 2013, 09:08:39 PM »

but you didn't have any foil backed insulation put on before they redid the siding did you? 

If you did, then you will have to get the antenna outside.

Thanks for the response.  I just Tyvek house wrap and James Hardie fiber cement siding on my house.   
Brad
MP 225 on the CR Indy Line

indyspy

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Re: Wiring for Scanner Antenna
« Reply #3 on: October 27, 2013, 09:12:46 PM »
You want it outside.

You used to be able to get away with attic stuff, but more and more building materials have some sort of metallic content in them.
Ether foil, or metalic flakes. I know there are now shingles with metallic flakes for durability.

Use thick cable, thicker the better. There are Chimney mounts or other options.

Also if your scanner is old, consider upgrading it. RRs went narrowband and narrowband on a wideband scanner will make everything sound very hushed.

FORGET the splitter. If you want to monitor your scanner from somewhere else in the house, buy an old fashioned baby monitor. Set the mic part next to the scanner. Set the receiver where you want it. I used to have use baby monitor for remote scanner listening before I got the stream server.
If in doubt, Notch it out!

DN_IN

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Re: Wiring for Scanner Antenna
« Reply #4 on: October 28, 2013, 06:59:41 AM »
If you must run a splitter, consider using 75-ohm co-ax, such as RG-6 low-loss satellite cable.  That way you can get a relatively inexpensive wide-band splitter-amp (intended for use with TV antenna feeds) which will preserve the signal levels at each port.  I'm going to get some heat from some people on here for saying it but this will work just fine, I use one to feed more than one scanner from a single antenna.  In fact, if you get an Antennacraft ST-2 outdoor scanner antenna, it comes with 75-ohm co-ax.  Most scanners will specify 50-ohm cable, but in fact, the impedance doesn't really matter so long as you aren't transmitting.  I picked up my RCA-branded (no doubt a ChiCom sweatshop product) splitter-amp at Menard's for around $20.  I don't have the specs in front of me but I recall that it covered from below what would be VHF-Lo band well into the GHz range, which should take care of anything you can get on a scanner, certainly the RR bands.  Put it as close to the antenna as possible and remember you will need a place to plug it in.  Mine works well.  I actually have very slightly higher signal strength levels on each output port than from the bare input feed, and it doesn't seem to inject any noise into the signal.
Armchair Railfan on the back porch listening to trains on the CSX St. Louis Line

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Re: Wiring for Scanner Antenna
« Reply #5 on: October 28, 2013, 11:24:28 AM »
As they say "we all have opinions".
One thing I learned, you do see a difference.  I use to argue that the lesser stuff wasn't that bad, until I started getting into the higher quality stuff thanks to the ATCS setups we do.  There is a HUGE difference even on a receive side.

haha, I'm not sure I'd install anything less than a LMR400 cable on anything I do, even basic scanner.  If you want the 800-900 spectrum then you better go good quality cable unless you are on top of the transmitter. 

Caylorman

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Re: Wiring for Scanner Antenna
« Reply #6 on: October 30, 2013, 11:43:55 AM »
While you will most likely get some attenuation from the materials in the attic (I've been researching path-loss through plywood for my own purposes), the attenuation may be made up by the increased height (increasing line-of-sight) that putting the antenna in the attic gives you. Unfortunately, this will require experimentation, to see what the trade-offs are.

As for cabling, if you want lower loss and to save some money, go buy a roll of RG-6 from Lowes.  Like it was posted before, mismatch loss from 75 Ohm coax won't make that much of a deal in a receive situation, and it's certainly cheaper than going out and buying LMR-400 or equivalent. 

As for splitters, I guess it depends on how close you are to what you want to listen to.  A 3dB drop equates to an approximately 30% decrease in range (if my math is correct), but really doesn't make that much a difference in audio quality.  What you really need is a multicoupler, which integrates a splitter with a pre-amp to make up the losses from the splitter.  You might try the TV splitter/amp combo suggested as well, but not knowing the specs on it, it may actually cause more of a problem.

Experimenting is always fun!

E.J.