Multiple scanners

[JAROUNDTOWN]

Hello,

After reviewing some of the threads on the site, I realized that this is the perfect place to find all the answers I am looking for.

My question is, as I have already read the article > Can I hook up 4 Motorola Trunk tracker scanners to one antenna using a multicoupler? I belive I can, so the question is > Which antenna should I purchase?

Also, I would like to put all 4 scanners in a box and put it behind my seat or the back of my truck. How can I run seperate volume controls for the devices so they can remain hidden behind a seat, and have the volume controls up in the front of the vehicle with me?

I have had this set up before, It's unfortunate that the person who wired it for me, is no longer on earth.

Any help or diagrams would be greatly appreciated.

Cheers

 

[sjlamb]

Hello,
Also, I would like to put all 4 scanners in a box and put it behind my seat or the back of my truck. How can I run seperate volume controls for the devices so they can remain hidden behind a seat, and have the volume controls up in the front of the vehicle with me?

Cheers

Just curious.... What is the purpose of placing (4) trunktracker scanners in a single vehicle? Is it your intention to run more than one at a time at varying volumes thru multiple external speakers?

 

[JAROUNDTOWN]

Multiple Scanners

I have had the set up before ... I own a towing company and listen to multiple bands throughout metro and O.P.P contract.

It is very distracting having 8 scanners in my centre console, so I place them behind the rear bench and just turn up the volume, and have them all going at the same time.

On one of my older trucks ( sold ), I had all the scanners behind the rear bench, and wires were run to the front of the truck. Right bye the ashtray, a plastic box was mounted with seperate volume controls for the individual scanners, and wired to individual small speakers which were mounted throughout the truck.

It was very easy to use, and I was able to adjust the volumes as I was going through the specific divisions.

I think I might have found what I need through research, but im not sure what audio requirments are needed and what type of volume control switch I should use. Theres only 1 person in the city who does this, and he charges $800 / per scanner to wire it into the truck, and he doesnt supply wiring.

I think an NKK miniature rotary switch should do the trick, just need to figure out how to wire it.

 

[Dewey]

Hello,

After reviewing some of the threads on the site, I realized that this is the perfect place to find all the answers I am looking for.

My question is, as I have already read the article > Can I hook up 4 Motorola Trunk tracker scanners to one antenna using a multicoupler? I belive I can, so the question is > Which antenna should I purchase?

Also, I would like to put all 4 scanners in a box and put it behind my seat or the back of my truck. How can I run seperate volume controls for the devices so they can remain hidden behind a seat, and have the volume controls up in the front of the vehicle with me?

I have had this set up before, It's unfortunate that the person who wired it for me, is no longer on earth.

Any help or diagrams would be greatly appreciated.

Cheers

I'm sure you mean "Trunk Tracker Scanners", as /\/\otorola doesn't make scanners (unless you mean using one of their radios as a scanner $$$$$). The only thing I can think of regarding seperate volume controls outside of wiring your own specialized box is to get four of the Uniden x96's (T or XT), and four remote heads. Still will take up some room, bit not as much as the four scanners in a box.

Dewey

 

[UPMan]

You might look at a passive mixer like:
Rolls MX41s 4-Channel Passive Mixer

 

[JAROUNDTOWN]

That might work, But do you think It will have any feedback ?

 

[DickH]

Hello,

After reviewing some of the threads on the site, I realized that this is the perfect place to find all the answers I am looking for.

My question is, as I have already read the article > Can I hook up 4 Motorola Trunk tracker scanners to one antenna using a multicoupler? I belive I can, so the question is > Which antenna should I purchase?

Also, I would like to put all 4 scanners in a box and put it behind my seat or the back of my truck. How can I run seperate volume controls for the devices so they can remain hidden behind a seat, and have the volume controls up in the front of the vehicle with me?

I have had this set up before, It's unfortunate that the person who wired it for me, is no longer on earth.

Any help or diagrams would be greatly appreciated.

Cheers

When I lived in Boston, I used to wire up vehicles for the fire buffs, TV photographers, etc. Some guys had as many as 12 radios in their cars, mounted in the rear. We ran speaker leads to volume controls in front going to several speakers. I only had 4 radios and I used just two speakers - used Motorola or GEs. I suggest you use one or two speakers. If you e-mail me, I'll show you how to wire it.

 

[DickH]

That might work, But do you think It will have any feedback ?

No, it won't work. The input impedance is 10K to 47K Ohms. Most scanner speakers are much lower impedance, some as low as 4 ohms.

 

[motorola_otaku]

Seriously? I put BNC F-M-F T-connectors on the backs of the radios and cut jumpers to length using Times LMR195 or Teflon RG58 to feed multiple radios off one antenna. Don't laugh until you've tried it; it works amazingly well. I have 2 996s fed with a single Antenex Phantom 800 antenna in the above-described manner in my car, and I notice not the slightest bit of loss in RX sensitivity versus feeding one at a time off the antenna. One thing you want to be careful about is that you don't cut any of your radio-radio jumpers to a 1/4-wavelength on any of your target bands because then it'll want to act like a coax trap and you'll end up attenuating your target band.

Personally, audio muxing is not something I'm a big fan of. I have one speaker per radio in my car for spatial diversity, and it helps to determine what you're listening to based on what direction it's coming from.

 

[sjlamb]

See Attache Diagram

Attached is a simple diagram to do what you want.

 

[sjlamb]

I only had 4 radios and I used just two speakers - used Motorola or GEs. I suggest you use one or two speakers. If you e-mail me, I'll show you how to wire it.

How do you get four radios to simultaneously feed separate audio to a single speaker?

 

[sjlamb]

Theres only 1 person in the city who does this, and he charges $800 / per scanner to wire it into the truck, and he doesnt supply wiring.QUOTE]

Bring the truck to Florida. I'll build and install the control, parts included, for a $100 per radio.

 

[scanbc780]

NCS Multi-RX™ "Receive Console"
Model NCS-3230

New Communications Solutions

 

[DickH]

How do you get four radios to simultaneously feed separate audio to a single speaker?

Using your terminology, tie one "outer" terminal of the pots together and wire it to one terminal of the speaker. Tie the other "outer" terminal of the pots together and wire it to the other terminal of the speaker.
The scanner audio outputs go to the "wipers" (arms) of the pots and the ground terminal of the pot. Looking at the back of the pots the ground goes to the leftmost terminal. Make sure the scanners all have a common ground.

 

[Mike_G_D]

What you really want to and should use are L-Pads rather than simple pots. The idea is to maintain a constant impedance as seen by the audio amplifier so that we don't short it out (some amps can't handle this for too long) as the last posters method will do (tying the output of the amp to the wiper of a pot - at extreme minimum it will present a near short to the amp which is not always a good idea) and so that the resulting control is smooth.

Here is a good description of how an L-Pad works together with a calculator to build fixed versions; there are links to L-Pad sources at the end also: L-PADS.

You would use four L-Pads - one for each speaker or, with a little more thought you could tie some outputs together for passive mixing into a lesser number of speakers. If you do this, ideally, you should add some more resistors for a passive combiner at least (or use a balance control).

-Mike

 

[sjlamb]

What you really want to and should use are L-Pads rather than simple pots. The idea is to maintain a constant impedance as seen by the audio amplifier so that we don't short it out (some amps can't handle this for too long) as the last posters method will do (tying the output of the amp to the wiper of a pot - at extreme minimum it will present a near short to the amp which is not always a good idea) and so that the resulting control is smooth.

Here is a good description of how an L-Pad works together with a calculator to build fixed versions; there are links to L-Pad sources at the end also: L-PADS.

You would use four L-Pads - one for each speaker or, with a little more thought you could tie some outputs together for passive mixing into a lesser number of speakers. If you do this, ideally, you should add some more resistors for a passive combiner at least (or use a balance control).

-Mike

This is good stuff. Thanks for sharing.

 

[DickH]

What you really want to and should use are L-Pads rather than simple pots. The idea is to maintain a constant impedance as seen by the audio amplifier so that we don't short it out (some amps can't handle this for too long) as the last posters method will do (tying the output of the amp to the wiper of a pot - at extreme minimum it will present a near short to the amp which is not always a good idea) and so that the resulting control is smooth. ...

... simple ... That's it - SIMPLE. If it's such a big problem, simply put a 5 Ohm resistor in series with the arm, or wiper if you prefer that word.

 

[Mike_G_D]

L-pads are pretty simple. Here is a perfectly good one for scanner use: Parts-Express.com: L-Pad 15W Mono 3/8" Shaft 8 Ohm | speaker mounting pad pa system pa speakers pa speaker PA mounting L-Pads l-pad l pad hardware drivers driver ads 8 ohm. That listing even includes a simple wiring diagram. Just purchase four of these and reproduce the wiring four times with four speakers (if using four speakers, of course).

To use only two speakers so that each speaker handles the mix of audio from two radios just add six 8 ohm resistors to make two 8 ohm two-way combiners. Solder three resistors together in the form of a triangle with each side a resistor. Solder output of L-Pads from two radios to each "side" of the "base" of the triangle and the speaker to the "top point" of the triangle. Do this twice - one for each two radio set and speaker. To be safe, use 2 watt or higher rated resistors (depends on the audio output power of your scanner; actually they won't necessarily be required to drop the full output level if all is hooked up ok and at normal listening levels).

Either way, you should be fine with zip cord or basic speaker wire as the wiring. Use four appropriate lengths of two conductor speaker wire with standard 1/8inch phone plugs soldered to one end. The other end goes to the L-Pad. Mount the four L-Pads up front in the cab (either in the console or inside a project box that is in turn mounted on or under the console wherever convenient) and run their outputs to the speakers with more speaker wire (or to the combiners and then the speakers if using the second two speaker method).

-Mike

 

[JAROUNDTOWN]

exactly

 

[vabiro]

Hi,

This isn't exactly what you're looking for, but may be useful anyway.

A couple of weeks ago there was a thread in the General Scanning forum

In it they recommended this:
Fleet Radio Products, LLC - For Fire / EMS / Police / HAM / Government

It will combine multiple radios into a single speaker.

Victor