Scanner Interference

The_Southern_Railfan · Mar 16, 2018

Hi all,
I have a narrowbanded Yaesu FT-2900r that I have scanning some railroad frequencies in the area and within the past year, it has started to develop this unusual interference. I've included a link in this post so everyone can take a listen. The entire setup consists of a dpdproductions traintenna mounted 54' in the air with a 65' run of LMR-400 coax straight to the back of the radio. I've tried different radios but the sound is there on everything I've hooked up. I have been struggling to figure this out for the past year and could really use some ideas. Thanks!

Link to audio: https://www.dropbox.com/s/p0o3kkc9vbcwf4h/interference.wav?dl=0

dlwtrunked · Mar 16, 2018

The_Southern_Railfan said:
Hi all,
I have a narrowbanded Yaesu FT-2900r that I have scanning some railroad frequencies in the area and within the past year, it has started to develop this unusual interference. I've included a link in this post so everyone can take a listen. The entire setup consists of a dpdproductions traintenna mounted 54' in the air with a 65' run of LMR-400 coax straight to the back of the radio. I've tried different radios but the sound is there on everything I've hooked up. I have been struggling to figure this out for the past year and could really use some ideas. Thanks!

Link to audio: https://www.dropbox.com/s/p0o3kkc9vbcwf4h/interference.wav?dl=0

Could be power line arcing. I have heard similar and once tracked one source down by hitting the poles with the underside of my fist. After a good number of splinters, I found the pole. As it was interfering with an aircraft communication, the power company quickly fixed it.

You need to walk your house and neighborhood with a portable radio and hope you get lucky--until that is done, you will likely not make any progress and will waste your time.

k9wkj · Mar 16, 2018

sounds powerline like
another thing is i do not believe the railroads ever had a narrow band mandate
so if they were banging on the edges of your filter it will cause a similar noise

nd5y · Mar 16, 2018

Sounds like power line noise to me and the raildroads DID have to narrowband.

ScannerSK · Mar 16, 2018

Definitely power line noise. I would walk around with a scanner tuned to an AM frequency (108-136 MHz) or a pocket AM radio to locate it. I have been known to go around kicking wooden light poles occasionally to find which one is the culprit.

Once you find the source, contact your local power company and most likely they will be able to assist in fixing the issue (as long as it is not on the customer's end).

Shawn

The_Southern_Railfan · Mar 16, 2018

Thanks everyone for the suggestions, I had suspected it to be power related but I questioned it because the noise seems to disappear overnight and return in the mornings. I thought for a while that is might be something overheating because of sunlight, but on some days it won't even be there at all.

KB7MIB · Mar 16, 2018

It goes away at night? Do you or any of your neighbors have solar panels on their roof?

John
Peoria, AZ

The_Southern_Railfan · Mar 16, 2018

KB7MIB said:
It goes away at night? Do you or any of your neighbors have solar panels on their roof?

John
Peoria, AZ

No solar panels, the radio is actually running in an old warehouse in an industrial section of town.

Ubbe · Mar 17, 2018

I agree with what others says, some kind of electrical interference and not computer, modem, LCD screen or similar products that interfere.

Go to AM mode on the same frequency using a portable scanner and select the smallest step size and tune around until you get the strongest signal and walk around the area and try to find the strongest source. You probably need to switch to a lesser antenna or use a paper clip or perhaps enable the attenuator in the scanner to reduce the signal to a workable level. The antenna on the scanner will have most attenuation when you point it at the source.

/Ubbe

DJ11DLN · Mar 17, 2018

KB7MIB said:
It goes away at night? Do you or any of your neighbors have solar panels on their roof?

John
Peoria, AZ

This is plausible. I once lived near a cracked high-tension insulator. When the humidity came up at dusk, it would usually quiet down. Once the sun came out the next morning and evaporated the moisture, the old bacon started frying in earnest. After much harassment the power utility finally did replace that one and the noise went away...they liked to come out early in the morning and give me the old, "Noise? What noise? I don't hear nuthin'!" routine.:roll:

The_Southern_Railfan · Mar 18, 2018

I think I finally found the source of the noise. It seems to be coming from the three transformers that supply the power to the warehouse. There are three fuses and 3 phase coming in so it could be any number of things. I'm going to call the power company today and let them know, hopefully they'll take care of whatever the cause is soon. Thanks again everyone for the ideas!

RRR · Mar 18, 2018

k9wkj said:
sounds powerline like
another thing is i do not believe the railroads ever had a narrow band mandate
so if they were banging on the edges of your filter it will cause a similar noise

The Railroad AAR frequencies were mandated to "narrowband" by the FCC on the same timeframe as everyone else.

All users of the AAR frequecies should be on 12.5 Khz ("Narrowband") by now, if not, they are in violation.

Ubbe · Mar 18, 2018

The_Southern_Railfan said:
hopefully they'll take care of whatever the cause is soon.

I don't know what kind of equipment they have to track down arcing but you probably have to take the day off to monitor the AM interference while they are working to really see to that they find the culprit.

/Ubbe

Scanner Interference

The_Southern_Railfan

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dlwtrunked

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k9wkj

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nd5y

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ScannerSK

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The_Southern_Railfan

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KB7MIB

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The_Southern_Railfan

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Ubbe

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DJ11DLN

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The_Southern_Railfan

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RRR

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Ubbe

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