Multiple scanners...one antenna?

[jonesey65244]

Can I feed several scanners from my one discone 30 feet up, or will there be signal loss from sharing with more than one radio?

Somewhat along these same lines, can I run more than one scanner from one wall wart power supply? My guess here is no, because it will reduce the amount of power going to each radio, but would like input from you guys, who I am certain know WAYYY more than I do.

Thanks in advance.

jonesey\
KC0OUF

 

[RKG]

You cannot just parallel multiple receivers to the same center pin of a single antenna coax fitting; they will interfere with one another.

You need a device known as a multicoupler to isolate the receivers from one another. At one time, there was an inexpensive multi-band multicoupler on the market that was aimed at consumer-grade scanning receivers; I tested one once and found that it wasn't a bad performer, particularly for the low price. I'll try to remember the name.

Edit: http://www.stridsberg.com/prod01.htm

 

[jmp883]

You can easily run multiple scanners off of one antenna. My listening post consists of 5 scanners connected to an external antenna on my old TV antenna mast. The radios are all coupled together with short lengths of coax combined with BNC connectors and adapters. Then one line runs to the antenna pre-amp and then out the roof-mounted antenna. I have little, if any, signal loss that I can tell.

As for power I highly recommend you buy a RigRunner from West Mountain Radio.
West Mountain Radio

If you look in the picture of my ham station you'll see my RigRunner on the wall behind all the equipment. My RigRunner powers all 5 scanners and all 3 ham transceivers using a 32 amp 12V power supply. Hopefully you have the mobile power cords for your scanners, if not you can either buy new ones or cut the wall warts off. You crimp their connectors onto your radios power lines and then plug them into the RigRunner. Connect your power supply to the RigRunner using the same crimp-on connectors and you're in business. No wall-warts clogging up power strips or wall outlets....and in my opinion, a much neater, more professional looking shack.

Good luck!

 

[N_Jay]

. . . . I have little, if any, signal loss . . .

Really?

. . . . that I can tell.

Tell how?

 

[jmp883]

N_Jay Quote:
Originally Posted by jmp883
. . . . I have little, if any, signal loss . . .

Really?
Quote:
Originally Posted by jmp883
. . . . that I can tell.

Tell how?

When I first set everything up years ago I left one scanner out of the loop and had attached its factory-supplied back-of-set antenna. It heard everything that the others did on the external antenna (with the preamp off). Then I put that single radio on it's own external antenna (w/o the preamp) and again all radios heard the same signals all the time. Was it a scientific test? Absolutely not.....but if those 4 radios with the lengths of coax running between them, and then a 30'-35' run to the external antenna, are hearing everything that the single radio can hear without any coax running into it then I guess there isn't all that much signal loss happening.

I use a preamp simply because of my situation in a valley. With the preamp off I can only hear the PD/FD/EMS units of my town and the one town immediately north and south of me, even using the external antenna. With the preamp on I can hear most all of northern NJ, southeast NY, NYC, and western Long Island, NY.

Like I said....nowhere at all a scientifically based statement! Just based on what my ears heard.

 

[smason]

Jonesy, have a look at the sticky thread at the top of the antenna forum, mucho discussion about multiple radios 1 antenna.

Some folks have good results just using a good quality cable/satellite splitter, it all really depends on how much signal you have available at the antenna. If you have lots, 3 db loss with a 2 way splitter doesn't hurt too bad.

 

[rvictor]

I think the short answer is that you can do it with splitters and you will lose 3db using a decent splitter to split one feed into two radios. In other words, half the signal goes to one and half to the other. If you've got enough signal that you can afford to lose 50%, you'll be fine. If not, you'll have insufficient signal.

73
Dick

 

[N9JIG]

I use multiple Stridsberg multicouplers in my shack, an 8 port wide band for general scanning, a 4 port 800 for Trunker/Pro96Com etc type use and a 4 port wide band for fire tone out receivers. With 3 antennas I am running 16 receivers. In addition my truck has a 4 port Stridsberg to allow 3 or 4 scanners on a single antenna.

Many multicouplers have a small preamp built-in to cover for insertion loss. This is usually makes the signal about the same with or without the multicoupler. The 800 MHz. Stridsberg unit has a stronger pre-amp so the signal is stronger at the radio end than it would have been otherwise.

While I prefer the Stridsberg, I have also had good luck using TV splitters and amps. Since the bands overlap most TV apparatus works well with scanners if you stay away from the cheap stuff. I use a nice Wingard TV amp and have used splitters in the past with no problems. The coax from several of my scanner antennas is quad shield RG6 coax marketed for satellite use. It works much better than RG-8, RG-58 or even LMR400 at 50 feet.

While you could get away with using T-adapters etc. if you have fairly strong signals for your targeted operations you also open yourself up to other issues with interference between radios and reduced signal strength. Splitters and multicouplers provide isolation between radios, an even impedance match and (in the case of active units) a pre-amp to overcome insertion loss.

 

[N_Jay]

T connectors are a bad idea. You will have no way of knowing what you are going to end up with. It is very easy to "accidently" end up with a very deep notch filter at a few random frequencies.

The right way is to use a splitter. You do not need the fancy/expensive ones with amplifiers. There is no magic to an amplifier set to offset the splitter losses. (just marketing hype).

If after all you splitting, you find you do need an amplifier, get ONE good one, and put it ahead of the splitters. Stacking multiple amplifiers (even if set to the magical "zero" gain) is not a good idea.

 

[3mary2]

splitters

O.K. so I don't know that much. All splitters I have seen have a cable TV connection on them. How do you do the the connecting? I'm guessing here (not to sure) Do you just use coax cable or TV cable and what size. Is there anywhere someone can point me to so as not to take up your valuable time?
THANK YOU IN ADVANCE FOR THE ASSISTANCE

 

[N_Jay]

The easiest way is to use F-connectors on RG-6 cable, and an adapter at the radio (or a cable with an "F" on one end and the needed connector for your radio on the other).

The very slight impedance issue with using 75 ohm cable and splitters is negligible.

 

[fmon]

I purchased one similar to this 4 out on Ebay a year or so ago.
ELECTROLINE EDA-UG2402 4-PORT CABLE AMPLIFIER - eBay (item 170178589194 end time May-06-09 23:04:49 PDT)

My cost was slightly less then 20 bucks including shipping. His shipping cost are slightly higher today.

The 4 outputs are on the same side of device and input is one of the connectors on opposite side. Power connection is the other. All connections are F and he provides the power supply with a 2 ft cable ready to hook up. You will need to purchase short lengths of scanner cable and 4 adapters for changing from F to B&C. RS has the necessary cables and adaptors.

 

[Turbo68]

Hi i use 2 Stridsberg-MCA204M vhf/uhf multicouplers and run 8 radios from each multicoupler with a T piece connected in the back of the radios and do not any signal loss at all.

Regards Lino.

 

[prcguy]

Yea, but cable TV amps are designed for a closed system with levels within known specs, hook an antenna to that and all bets are off. These amps are not made with noise figure in mind and the signal levels to a TV tuner are quite large compared to what you might want to listen to on your scanner.

If you want to do it right get the right part, a multicoupler or good quality high level wide band preamp feeding a quality splitter and don't get too crazy with the gain.

The "T piece" comment in the last post will incur at least 3dB loss and probably more.
prcguy

I purchased one similar to this 4 out on Ebay a year or so ago.
ELECTROLINE EDA-UG2402 4-PORT CABLE AMPLIFIER - eBay (item 170178589194 end time May-06-09 23:04:49 PDT)

My cost was slightly less then 20 bucks including shipping. His shipping cost are slightly higher today.

The 4 outputs are on the same side of device and input is one of the connectors on opposite side. Power connection is the other. All connections are F and he provides the power supply with a 2 ft cable ready to hook up. You will need to purchase short lengths of scanner cable and 4 adapters for changing from F to B&C. RS has the necessary cables and adaptors.

 

[donc13]

Read the sticky...all your questions are answered there

http://www.radioreference.com/forum...5054-using-one-antenna-multiple-scanners.html

 

[N_Jay]

. and do not any signal loss at all.

Measured how?

 

[Turbo68]

I do not have any equipment to measure its done on 1 Icom-AH7000 discone connected direct to one radio and the other Icom-AH7000 on the stridsberg multicoupler connected to 8 radios using a lot of the same frequencies on airband & other bands vhf/uhf bands with the squelch all the way out and the signal bars are all the same on all radios.

Regards Lino.
ALINCO-DJX2000
AOR-3000/AOR-3000A/AOR-8200M3
GRE-PSR500
ICOM-RX7/ICOM-R3/ICOM-R20/ICOM-PCR1500/ICOM-PCR1500/ICOM-PCR2500/ICOM-R9500
KENWOOD TS-480SAT
REALISTIC-PRO2035
UNIDEN-245/UNIDEN-396/UNIDEN-780
YAESU-VX7R/YAESU-FT8800R/YAESU-VR500

 

[jonesey65244]

Hi folks.

I want to thank you for all the responses. Even though it looks as though I may have opened a worm can.

The price or the multicouplers I looked at seem to be overkill for my purposes. I can put up a couple more discones for less, and since 1 or 2 of the scanners may be dedicated to a certain ham band, maybe a dipole for that band will be the answer.

As far as using a RigRunner to power several scanners, I have one and thought of that, but I would like to keep my electric bill in hand, and a 35 amp power supply (which I do own) running 24/7 makes me cringe a bit.

Again, I thank all of you for your responses. I knew this would be the place to get answers.

jonesey65244
KC0OUF