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Local AM/FM radio station interference on UHF band

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jaredonfilm

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First post, mods, if I am posting this in the wrong forum please feel free to move it. I searched for AM/FM interference on UHF and did not come up with much regarding this matter.

I work in an industrial setting. We have a UHF radio network for about 16 radios with 3 repeaters. Every component is older Motorola (HT1250-LS handhelds). Recently, I got tired of carrying the heavy, clunky radios which have quite poor performance. I was recommended the Baofeng UV-5R(V2+) from a friend. I purchased one on Amazon and have slowly been becoming a radio geek since. (studying ARRL tech book, taking exam in April)

Anyways, I programmed my radio to our six work frequencies using CHIRP. It works great, awesome battery life and TX/RX is better than the Motorola's.

I have noticed recently, that I was picking up music on my radio (on clear days). I thought maybe I had a bad radio for a bit but the other non-motorolas at our job site pick up the same thing on the same primary channel we use. The TX was so clear the other day, I heard the music stations call sign. I looked it up and it is a local AM/FM station which transmits on 88.1 FM and 1080 AM. We are using 457.525 Mhz as our primary work UHF frequency.

Any explanation as to why this is happening? Could this explain the poor performance of our installed radio system? Are our Motorola's RXing this but squelching it out possibly?

I am not really looking for a solution, but simply curious for my own sake. Any answers would be greatly appreciated!.

Thanks!

-Jared
 

NC1

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One or more of the repeaters may need some RF filters to eliminate the interference.

Take one repeater and shut it off for a day and see if that helps, if not, then hook it back up and do the same with the next. If that is not helping, then try turning the 3rd one off for the day.

Something is getting into the line somehow. How far away is the radio station tower on FM?

What are the other frequencies you use? It could be a harmonic on one of them, but can't determine without knowing all the frequencies.
 

kayn1n32008

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The issue could also be caused by poor shielding with in the cabling in the repeaters. How close to the FM/AM transmitters is your repeaters?
 

bharvey2

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I'd suspect that the front end on the non Motorola radios are less discriminating and therefore picking up the am/fm stations. If your repeater were picking it up the noise then all of the radios should be receiving it. I've heard of people having problems with Baofengs and Wouxuns in high RF environments. I have a few and I haven't experienced the problem so maybe it's a quality control issue.
 

ecps92

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How close to your Facility are the two Transmitters ? (AM / FM Stations)

First post, mods, if I am posting this in the wrong forum please feel free to move it. I searched for AM/FM interference on UHF and did not come up with much regarding this matter.

I work in an industrial setting. We have a UHF radio network for about 16 radios with 3 repeaters. Every component is older Motorola (HT1250-LS handhelds). Recently, I got tired of carrying the heavy, clunky radios which have quite poor performance. I was recommended the Baofeng UV-5R(V2+) from a friend. I purchased one on Amazon and have slowly been becoming a radio geek since. (studying ARRL tech book, taking exam in April)

Anyways, I programmed my radio to our six work frequencies using CHIRP. It works great, awesome battery life and TX/RX is better than the Motorola's.

I have noticed recently, that I was picking up music on my radio (on clear days). I thought maybe I had a bad radio for a bit but the other non-motorolas at our job site pick up the same thing on the same primary channel we use. The TX was so clear the other day, I heard the music stations call sign. I looked it up and it is a local AM/FM station which transmits on 88.1 FM and 1080 AM. We are using 457.525 Mhz as our primary work UHF frequency.

Any explanation as to why this is happening? Could this explain the poor performance of our installed radio system? Are our Motorola's RXing this but squelching it out possibly?

I am not really looking for a solution, but simply curious for my own sake. Any answers would be greatly appreciated!.

Thanks!

-Jared
 

Rred

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Joined
Nov 21, 2014
Messages
829
As Harvey said. The BaoFengs may appear to be "better" radios, but there are some weaknesses in them compared to top-tier traditional radios.

Among the top three brand name ham brands, for quite some time people would say "these are greater, have more features, are just as good" while other ops in big cities would say "They're junk, the get all sorts of interference" because one particular brand just wasn't as good at keeping a clean signal.

Last year the ARRL tested a number of the Chinese SDR's at the Daytona Hamfest, radios that hams owned and used. Guess what? None of them met technical requirements, while the three brand names from Japan all still did.

Since BaoFeng (the Chinese manufacturer) refuses to answer email from America, it is anyone's guess as to what a particular radio has been made to do.
 

IAmSixNine

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WHAT?? You say"Every component is older Motorola (HT1250-LS handhelds). Recently, I got tired of carrying the heavy, clunky radios which have quite poor performance." Not sure what your experience is with radios but the HT1250 series radios were great radios. I would never describe them as heavy, or clunky or poor performers. Id like to know more about that. I have owned several of them. HT1550XLS in VHF and UHF. HT1250 UHF, HT1250LS and HT1250LS+ all of them were great. Ive also had Baofeng and Wouxun radios (Wouxun being my preference over Baofeng).
Also whom ever recomended the Baofeng radios must not use the radio. Its not a great radio for a commercial use environment.
I know im not addressing your interference issue but dang the HT1250 units are great radios.
 

Chronic

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I am wondering if the system is using a PL or are just wide open frequency. If you could set up the PL then the radio station most likely would not be heard.
 

bharvey2

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According to the frequency he uses and the one that is causing interference, the is over a 350mhz spread. The FM station shouldn't be breaking his squelch. Even if he's only hearing the interference when another user transmits, this point toward front end filtration trouble.
 

popnokick

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Nearly every Baofeng HT has a single-button FM broadcast receive button (88-108 mHz). Is it safe to assume that button is NOT being pressed by any user? I've lost track of the # of times I've hit that button by accident when trying to perform some other function... and hearing an FM radio station come in clear as day.
 

ecps92

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That one frequency mentioned is also a regular Fast-Food Freq, can I have some frys with that AM/FM Weather ??
According to the frequency he uses and the one that is causing interference, the is over a 350mhz spread. The FM station shouldn't be breaking his squelch. Even if he's only hearing the interference when another user transmits, this point toward front end filtration trouble.
 

jonwienke

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PA
And +1 on it probably being an inadvertent activation of the FM broadcast receiver on the Baofeng. You can deactivate it in CHIRP. Try that and see if the problem goes away.
 

jaredonfilm

Newbie
Joined
Feb 8, 2017
Messages
2
Something is getting into the line somehow. How far away is the radio station tower on FM?

What are the other frequencies you use? It could be a harmonic on one of them, but can't determine without knowing all the frequencies.
The radio station is about 3-5 miles away.

We have 5 other UHF frequencies programmed into our radios but 457.525 MHz is really the only one in use. I'll try some of our other frequencies today to see if I pick up the radio station on them.

WHAT?? You say"Every component is older Motorola (HT1250-LS handhelds). Recently, I got tired of carrying the heavy, clunky radios which have quite poor performance." Not sure what your experience is with radios but the HT1250 series radios were great radios. I would never describe them as heavy, or clunky or poor performers. Id like to know more about that. I have owned several of them. HT1550XLS in VHF and UHF. HT1250 UHF, HT1250LS and HT1250LS+ all of them were great. Ive also had Baofeng and Wouxun radios (Wouxun being my preference over Baofeng).
Also whom ever recomended the Baofeng radios must not use the radio. Its not a great radio for a commercial use environment.
I know im not addressing your interference issue but dang the HT1250 units are great radios.
The 1250 becomes quite the nuisance when you have to carry (back pocket with ext speaker/mic) it for 8+ hour days, 7 days a week. I am not saying that the 1250 in general is a poor performer, but that in use on our system, it does not work well.

The Baofeng may not be the best for an industrial environment but at $32 a piece, they are basically disposable.

I am wondering if the system is using a PL or are just wide open frequency. If you could set up the PL then the radio station most likely would not be heard.
Wide open I believe. I did not have to program in any PL on CHIRP for my radio to work here.


Nearly every Baofeng HT has a single-button FM broadcast receive button (88-108 mHz). Is it safe to assume that button is NOT being pressed by any user? I've lost track of the # of times I've hit that button by accident when trying to perform some other function... and hearing an FM radio station come in clear as day.
And +1 on it probably being an inadvertent activation of the FM broadcast receiver on the Baofeng. You can deactivate it in CHIRP. Try that and see if the problem goes away.
This is not the case, I am familiar with the functions/buttons on the radio.

Thanks for the replies.
 
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