2 scanners 1 device

TongSlinger

Longtime Listener
Premium Subscriber
Joined
Mar 17, 2005
Messages
79
Location
35.393528, -99.467468
I have 2 996 scanners P2 and XT. What would be the performance loss to attach them both to one discone antenna? Also, Can i stream the audio from both scanneras and "t" them together and funnel the audio from both scanners into a single cable to run into my sound card on my computer? There would be a possibilityy of back feeding one of the scanners with the audio from the other.. Would this cause any issues with sensitivity or any other functions of the scanner?
 

w2lie

New York DB Admin
Database Admin
Joined
Mar 2, 2004
Messages
1,206
Location
Long Island, NY
You can use a multi coupler to combine the two scanners into a single antenna.
You can use a Stereo channel splitter for your sound card and bring one scanner in the left channel and one scanner into the right channel to split your feed into two different feeds, or combine them into a single feed in stereo.

My setup uses an 8 port multi coupler to split my antenna to 8 scanners and I bring my scanners into proscan and doubling my input capacity by splitting the left and right channels on the sound card.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
4,677
Location
Stockholm, Sweden
If you connect scanners in parallel to one coax you will get degradation in sensitivity depending of what frequency band the other scanner are using. If they are on the same frequency band you will probably see that the signal strenght are cut in half, a 3dB loss, when the antenna signal are evenly distributed to the two scanners.

If one scanner are on 800Mhz band and the other on 400Mhz it might be very little loss compared to using only one scanner.
It only costs a T connector so it is a cheap solution. If you use passive splitter, a CATV splitter costs $5, it will interact between scanners much less but you will also have at least a 3dB degradation at all times.

Using an active tv splitter might work, they can have high internal noise and people use them with scanners where they often will give a too high signal level and overload the scanners and desense them.

Using a real multicoupler will give less problems but the cost will be something like $200.

/Ubbe
 

Jphila20

Member
Joined
Dec 17, 2004
Messages
136
Location
Southern Lorain County, Ohio
I should know the answer to this, but..........
What's the basic difference between an antenna splitter and a Multicoupler? Multicouplers seem to point more towards 1 antenna to multiple receivers where the splitters does the opposite. I need to pull in from some distant locations and still receive locally. Have an older Radio Shack tri-band antenna, a 700mhz beam and a 800mhz beam. The antennas are mounted inside in an attic. Really don't want to put anything outside. Thoughts?
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
4,677
Location
Stockholm, Sweden
Splitter are supposed to be a passive device that always attenuate signals. Multicoupler are supposed to always have an inbuilt amplifier to give no loss to the antenna signal when it is split to several outputs.

That amplifier can be of different qualities, the tv/broadcast radio ones usually being of poor quality giving additional noise and easily overloads. The more expensive ones like Stridsberg are designed more with low signal monitoring in mind and better strong signal handling. But any active devices usually behaves better when filtering out non desired signals like FM broadcast and pager transmitters in the VHF band.

I personally use $25 PGA103+ based amplifiers that have both lower noise and better strong signal handling than Stridsbergs devices. Then I use CATV splitters to suit my needs. It's much cheaper than a Stridsberg and works better, especially if you have the amplier at the antenna and the splitter down at your receivers. The whole coax loss, and eventually any impedance mismatch, are then instead turned into positive dB's that improves reception with the same amount of dB that used to be the system loss. I have a variable 0-20dB attenuator to lower the signal into the splitter so that the outputs are at a level where my scanners have their best sensitivity, and of course a FM trapfilter.

/Ubbe
 

TongSlinger

Longtime Listener
Premium Subscriber
Joined
Mar 17, 2005
Messages
79
Location
35.393528, -99.467468
Thanks for all the replies so far, they have been knowledgeable. Scanning frequencies between 146-855, What would be the best discone for the dual use setup. Does any one have better features than the other in this appkication? I seem to be getting a lot of interference from my wireless router that I found with the SDR rig. I had no idea that everyday devices and appliances make so much noise.. How do i get rid of that?
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
4,677
Location
Stockholm, Sweden
If you also have network cables connected to the WiFi router then switch to double shielded cables STP. The power cable can also radiate so put a clamp on ferite core on it. Also computer screens radiate so try and change the update rate, maybe 75Hz to 60Hz or similar to move the interference to another frequency that hopefully doesn't interfere with your scanners frequencies.

Unidens scanners have relative good shielding using double screening, but you then also need to use good coax with double shielding, RG6 being the cheapest one.

/Ubbe
 

TongSlinger

Longtime Listener
Premium Subscriber
Joined
Mar 17, 2005
Messages
79
Location
35.393528, -99.467468
You can use a multi coupler to combine the two scanners into a single antenna.
You can use a Stereo channel splitter for your sound card and bring one scanner in the left channel and one scanner into the right channel to split your feed into two different feeds, or combine them into a single feed in stereo.

My setup uses an 8 port multi coupler to split my antenna to 8 scanners and I bring my scanners into proscan and doubling my input capacity by splitting the left and right channels on the sound card.
I ran the two 996 scanners audio outputs into a single RCA Plug cable with a Y (2 -1) adapter and plugged it into sound card and split each scanner into left and right channels. Would there be any chance of doing any damage to the scanners that were tied together through the audio outputs?
 

wtp

Member
Joined
Apr 3, 2008
Messages
2,934
Location
Port Charlotte FL
about the antenna thing...
why not put the closer/stronger signal frequencies in one radio and use the back of the set for that one and the discone for the other ?
 

a417

!#
Joined
Mar 14, 2004
Messages
1,522
.

did you sum the audio together into a mono feed (and thussly connecting the audio amps to each other) , or did you separately feed each scanner into a stereo sound card feed with each feed on separate sides (one to left, and one to right)?
 

TongSlinger

Longtime Listener
Premium Subscriber
Joined
Mar 17, 2005
Messages
79
Location
35.393528, -99.467468
I have them separated by system capability. when experimenting, i found that for some reason when i program the identical system into both scanners with both rear mount factory antennas, there is a big difference in receiving. The reason I was doing that is I want to know which scanner receiver different frequencies and even systems so i could program the common frequencies into the best receiving scanner. Only thing is, a couple of trunked systems are over 60 miles away. and we all know the P2 has more capabilities. The best solution in my opinion would be to put an outside antenna on both 996's. Since the 996's are capable of much more than the SC200 and 246T. I could us them to receive the analog non-trunked. Well i could use the 246 do do some analog trucking duty. The possibilities are endless if i could put all four on the outside discone.
 

TongSlinger

Longtime Listener
Premium Subscriber
Joined
Mar 17, 2005
Messages
79
Location
35.393528, -99.467468
.

did you sum the audio together into a mono feed (and thussly connecting the audio amps to each other) , or did you separately feed each scanner into a stereo sound card feed with each feed on separate sides (one to left, and one to right)?
I T'ed them into one cable and inserted that single jack into the audio in jack on the back of my computer.
 

a417

!#
Joined
Mar 14, 2004
Messages
1,522
I T'ed them into one cable and inserted that single jack into the audio in jack on the back of my computer.
almost what I was looking for...

do you know if that "T" combined/summed the mono channels into a single channel, or did it separate them into left and right feeds into the computer?
 

TongSlinger

Longtime Listener
Premium Subscriber
Joined
Mar 17, 2005
Messages
79
Location
35.393528, -99.467468
What ever the output of the 996's eith mono or stereo, I did not isolate the stereo signal into 2 channels. Unfortunately I pushed both 996's into the computer via stereo. nothing was separated. I hope that explains the setup I used.
 

TongSlinger

Longtime Listener
Premium Subscriber
Joined
Mar 17, 2005
Messages
79
Location
35.393528, -99.467468
What ever the output of the 996's eith mono or stereo, I did not isolate the stereo signal into 2 channels. Unfortunately I pushed both 996's into the computer via stereo. nothing was separated. I hope that explains the setup I used.
[/QUOTE]
IMG_4737.jpg
 

jonwienke

More Info Coming Soon!
Premium Subscriber
Joined
Jul 18, 2014
Messages
11,748
Location
VA
I ran the two 996 scanners audio outputs into a single RCA Plug cable with a Y (2 -1) adapter and plugged it into sound card and split each scanner into left and right channels. Would there be any chance of doing any damage to the scanners that were tied together through the audio outputs?
Yes. You'll need separate ground loop isolators on each scanner, or risk damaging the audio amp.
 

AB5ID

Member
Joined
Aug 6, 2007
Messages
202
Location
Lee's Summit, MO (Kansas City)
Even with ground loop isolators, you're connecting two low-impedance devices together which does not seem like a good idea. in addition to using ground loop isolators, You may want to use audio attenuators to isolate the radios from seeing each other. That way, each radio can see its own low impedance load and have high impedance outputs tied together and summed. Similar to having the 2 scanners connected to an audio mixer.
 
Top