Signal comes in clearly normally but fades out once in a while?

In my area, there is a county PD freq at 453.375 and another at 453.300.

453.375 is only about 4.7 miles away on one tower and 10 miles away on another tower.

453.300 is roughly 13+ miles away on it's multiple towers.

For some reason even though 453.375 for years came in crystal clear, lately it has been coming in clear about 90% of the time but then randomly fades out like somebody took the antenna off while it was receiving.

This lasts roughly 2 seconds or so but sometimes longer.

I have tried 4 different scanners in my place and they all experience this.

I also have tried many different antennas and antenna locations. I even tried two different amps. The amp brings in 453.300 and other distant freqs in extremely well, but it doesn't seem to fix 375.

What I am trying to determine is, is this most likely caused from low signal or would it be more likely some interference source locally?

Also no other frequencies from the same towers as 375 seem to be affected.

Could be lots of things -- definitely sounds like something changed in the transmission recently - be it an adjustment to the signals/transmitters (power, narrowbanding, etc.) or some other signal that periodically causes interference.

Have you tried (if possible) adjusting the frequency from "FM" or "NFM"?

If you can pin down when the fading occurs, it would be interesting to know what happens if/when you move closer to one of the transmitter sites.

Do you know the FCC license for the transmitter?

FCC

troymail said:

Do you know the FCC license for the transmitter?

Click to expand...

WPAI297

RedPenguin said:

WPAI297

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The only real thing that jumps out when I look the license over is a possible change to narrowbanding emissions.

Are you set to FM or NFM?

troymail said:

The only real thing that jumps out when I look the license over is a possible change to narrowbanding emissions.

Are you set to FM or NFM?

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I had my BR330T set to NFM. The other radios I was testing with are older and don't have options to select the modes.

If you could move your scanner to another location, such as at friend or relative's home or even mobile, that would help rule out interference issues in or near your home.

Also it's possible the "system" is having problems on "their end". While their cables and antennas are made to be resilient, they don't last forever.

ofd8001 said:

Also it's possible the "system" is having problems on "their end". While their cables and antennas are made to be resilient, they don't last forever.

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I could definitely believe that. One agency in the area alone had two separate times where their repeater malfunctioned and they had to go around using Talkaround.

It sounded like the one time they said "Ice on the Repeater".

Also I know the City PD channel (453.650) has been iffy in my area for the LEOs themselves. Not good when my area gets a lot of calls for them.

Also I'm not sure if this helps much or not but when 453.375 is working and not breaking up, I noticed it does have much more static in the background than 453.300 or any other county freq for that matter does even though it's much further away.

RedPenguin said:

Also I'm not sure if this helps much or not but when 453.375 is working and not breaking up, I noticed it does have much more static in the background than 453.300 or any other county freq for that matter does even though it's much further away.

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Possibly reduced power? I'd seen some conventional channels reduced in power over time... sometimes due to mandates and other times because the signal was just too strong and interfering with other users.

Historically, signals got blasted over large areas but things seems to be getting "tightened down" these days.

I found a solution somewhat.

For some reason, if I use my CATV amp laying around that has helped my other radios out, it clears up the signal somewhat.

Though oddly what seems to really help is, if you take a coaxial cable off the output of the amp and then put a coupler on then add another coaxial then to the scanner, oddly that really cleans it up.

Not really sure why direct coaxial vs two coaxials with a barell coupler make any real difference.

Although I did also plug the one scanner I want to pick up .375 in to a different outlet, so maybe that did something also.

Well so far everything is sounding great.

Even a similar located freq to 453.375, 453.15 is also coming in very clear now.

I guess something was going on with the power strip the main scanner was plugged in to that somehow affected every other scanner that I tested with.

I did some further testing and it appears it was actually both actions that solved it.

It appears that some of the interference like 80% was caused by the wall wart of the radio mainly used to pickup 375.

The rest was that I had to use my CATV Amp through 3-splitter feeding two other radios, then put a 0-20dB Variable Attenuator on and bring the signal down slightly.