Weird audio problem on 1 frequency only

SaukScanR

Member
Feed Provider
Joined
Jul 6, 2014
Messages
21
Location
Baraboo WI
I run the Uniden BCT 15x (my Broadcastify feed) and the BCD996xt using an AntennaCraft ST2 antenna mounted in my attic. Antenna coax connects to Electroline EDA2800 amplifier under my desk, that splits coax to each scanner. Has worked great for years, but over the last few months I have been running into intermittent bad audio on only 1 frequency. It's the main county sheriff repeater (155.7). The problem started as just an annoying fart type sound at the end of each transmission, but seems to have gotten much worse, but still intermittent.
For troubleshooting, I tried disconnecting the coax from the BCD996xt and connected the scanner to a cheap 36" wire antenna. No more problem on that scanner. I have also run the antenna directly to a splitter, without the Electroline amp, but the problem still persists.
I just do not understand how an antenna issue could affect only 1 frequency! I created an mp3 file of this bad audio to attach, but it appears I can only attach image files.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,122
Location
Stockholm, Sweden
You have to compress the mp3 file to zip to be able to post it.
It sounds as if you have an interference on only that frequency. If you can edit the channel to not use CTCSS it probably will be easier for you to hear the interference. Turn down squelch to 0 as well when the transmission starts to hear what happens to the audio when the transmission ends.

/Ubbe
 

gh6406

Member
Premium Subscriber
Joined
Apr 25, 2013
Messages
168
Location
Dalton,Ga
Sounds like an adjacent channel is interfering. Possibly 155.685 or 155.715. I see 155.685 is used on WISCOM statewide system.
 

Ronaldski

MI DB Admin
Database Admin
Joined
Aug 23, 2005
Messages
2,440
Location
Bay City MI
New electronic equipment recently? Wifi routers generate interference around that range at east my netgear does. The marine band has some channels interference. Pull the plug on the router, gone. I reduced quite a bit by just moving it somewhat.
 

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,122
Location
Stockholm, Sweden
If you hadn't mentioned that the 996 receives fine with another antenna I would have though that they had a problem with their transmitters subtone generator. The 88Hz subtone increase in strenght and finally makes that fart sound when their transmitter unkeys. It also sounds as the scanner (not possible if it is heard on two scanners) or transmitter drift in frequency. It doesn't sound as any adjacent frequency interference or electronic device like a router that are the problem.

I would had been 99% sure that it was a transmitter problem until you verified that another antenna solved the problem.

Can you make another recording without ctcss programmed and with squelch open, set to 0?
The Electroline are the only active component in the antenna system?

/Ubbe
 

SaukScanR

Member
Feed Provider
Joined
Jul 6, 2014
Messages
21
Location
Baraboo WI
Maybe started when I moved my Netgear router to a higher shelf. Will try relocating to see what it does.
Ubbe, I will do more reading tomorrow to figure out what ctcss is. Here's a screenshot of Freescan. 1592378892509.png
And yes the Electroline was the only active.
Edit: Tvengr, you mentioned turning on the attenuator. Would that mean placing a checkmark in Att in this screenshot?
 
Last edited:

Ubbe

Member
Joined
Sep 8, 2006
Messages
5,122
Location
Stockholm, Sweden
ContinuosToneControlledSquelchSystem or someting like that. It is the subtone 82,5Hz. Set it to None just as a test and turn down squelch to 0 so it will be open with noise, and interference, when the transmission ends.

If you hear only clean noise while there's no transmission and it only burps at the end of actual transmission, then there's very lite probability that you have a local interference. Either it is the scanner or the transmitter that are faulty. But if you hear strange sounds while no one are transmitting and with your squelch open then you have interference that could come from electronic devices or another transmitter on another frequency.

/Ubbe
 

Ronaldski

MI DB Admin
Database Admin
Joined
Aug 23, 2005
Messages
2,440
Location
Bay City MI
Unless your a few miles from the tower I wouldnt turn on the attenuater, kills the signal 20db, since you also have to have the PL(CTCSS) on, needs the extra signal to have the radio to decode the tone. Just the chance you'll miss transmissions.. I thought it might be a router issue, I would try moving the cabling around first, shouldnt have to move the router to a new location hopefully. Yep routers are notorious for interference. Maybe coil up the wiring, could help or make it worse. Read in one of the links below said it is the clock frequency inside the router.
Another option is maybe getting a ferrite .

See One solution for router interference
 

tvengr

Active Member
Joined
Feb 10, 2019
Messages
3,154
Location
Baltimore County, MD
I tried disconnecting the coax from the BCD996xt and connected the scanner to a cheap 36" wire antenna. No more problem on that scanner
This sounds like a overload or intermod problem. That is why I suggested trying turning on the attenuator. It definitely sounds like an interference problem. The IF exchange could be of some help here.
 

Ronaldski

MI DB Admin
Database Admin
Joined
Aug 23, 2005
Messages
2,440
Location
Bay City MI
Easiest to find a correct setup is if you know how is to remove the PL tone from that frequency then press HOLD on the radio to stay on it. Then go to your router and start manipulating it till the interference is hopefully gone. Then go back and put the PL tone back in.
 

SaukScanR

Member
Feed Provider
Joined
Jul 6, 2014
Messages
21
Location
Baraboo WI
I'm trying some things, and will update the post eventually.
I did wipe out all programming for Sauk County and downloaded new freqs from RR on the BCD996xt. Not sure why that would help, but that may have fixed it. Waiting to make sure it's fixed, then will try it on the BCT15x next.
 

SaukScanR

Member
Feed Provider
Joined
Jul 6, 2014
Messages
21
Location
Baraboo WI
I did wipe out all programming for Sauk County on both scanners and downloaded new freqs from RR. So far, not hearing any problems!
I did not move the router or cabling, and have the amplifier connected again. Will listen closely for a few days to make sure it stays fixed.

I do not understand what may have been wrong, but really appreciate all of your suggestions!
 
Top