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Old 03-15-2013, 12:28 PM
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Default One frequency bleeding over another?

I have an odd situation with my feed radios. I am using two different radios on one stereo feed. I am experiencing a control channel like sound which is the result of one frequency bleeding onto another from radio to radio. I tried swapping out a radio but still have this problem. Where to start???

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Old 03-17-2013, 7:53 AM
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First would be to isolate the ground connections between the two scanners by inserting audio isolation transformers (ground loop eliminators) in the external speaker to computer cables. This will eliminate any potential difference in ground potential between the two scanners and the sound card. The negative side of the external speaker jack on some devices is not at ground potential. In some scanners both the tip and ring are driven in opposite polarity to increase the audio power. Grounding the negative side by sharing a common connection to another scanner will often cause problems.
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Old 03-29-2013, 11:46 AM
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I run a stereo feed and had some bleed over between radios.
There were several things that were causing it.

1) I was sharing an antenna between the two scanners using a splitter made for just that purpose. I bought a second antenna.
2) My sound card had some "bonus" settings I had to turn off. 3D sound along with other enhancements. I turned them all off.
3) The sound mode on the card made a difference. Game mode vs theater mode, etc. I chose the one that stated it was best for voice or spoken word as opposed to music.

With all that I have good separation. Different devices will give you different results. My PC gives me total separation where my phone isn't so clear on the separation unless I drop one of the balance controls all the way down.

Jay
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Old 04-03-2013, 7:07 PM
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I recently realized 154.370 will bleed over 154.235 even with both frequencies programmed on the same radio. I am in fact sharing one antenna to two radios. I've been running this set up for a few years without incident. This problem just popped up a few weeks ago. I will try to seperate the two with independent antennas as soon as i can get around to it.

Thanks for the help.
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Old 04-02-2014, 11:34 AM
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After a year of good audio the trouble is back. Was able to capture the noise on my phone. Is this what INTERMOD sounds like? Ordering a notch filter today.

Apr 2, 2014 - YouTube
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Old 04-02-2014, 12:25 PM
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First of all I would turn off the priority.

It looks like you received a control channel and the scanner switched to channel 51 - 851.2750 either by the priority or maybe by the data from the control channel.

I would do a reset and only program the frequencies for you feed, and don't use the priority. Priority on a feed makes it extremely hard to follow the traffic anyway.
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Old 04-03-2014, 10:30 AM
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Quote:
Originally Posted by saleen49 View Post
After a year of good audio the trouble is back. Was able to capture the noise on my phone. Is this what INTERMOD sounds like? Ordering a notch filter today.

Apr 2, 2014 - YouTube
It does sound like control channel, but it could also be a paging service or strong signal is overloading your scanner.

This sounds very close to what happens to my scanner when dispatch set off the dispatch tone channel 154.430 for the local VFD which has a tower just few miles from my home. It overloads other local VFD ch. 154.190 and the EMS ch. 155.205 along with couple others as well. I looked into notch filter, but that would cut out most of what I listen to. Lucky this VFD is just about done changing over to digital, so my problem is slowly going away.
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Old 04-10-2014, 9:13 AM
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Update:

I normally get the INTERMOD during transmission of a department I monitor that is roughly a half mile from my locaton. The agency will tone out and the INTERMOD sometimes covers the tone and carries into part of the dispatch.I'm beginning to wonder if anttena design has something to do with it? I've tried just about everything else I can think of to isolate this.
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