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What to do about an interference issue

E

EvinLakeson

Good morning, Eastern NC

I live in Newport and i am just about feed up with FM interference. Every time i am driving about a 3 mile stretch from MHC to Newport I have to change stations. (I have found the interference to be about a 5ish mile circle around the broadcaster in question.) I Normally listen to a rock station from Jacksonville, But it is often overpowered by a christian station here in Newport. I suppose this is due to the fact that i listen to it on a VHF ham radio with an FM function. BUT, Even if i am in my parents car, which has a newer radio, The same station is still being overpowered, but the audio doesn't bleed through.

Does anyone have any suggestions? I dont really want to get anyone in serious trouble, i just want my music.
 
I'm guessing the station in question generating the interference is WLGP 100.3, a 100kW licensee with its transmission facility along US 70 in Newport. It is likely generating front-end overload in your receiver, essentially turning down the gain in the receiver because of the presence of this very strong signal.

There's not generally much to do about this. It is very unlikely that WLGP is operating beyond its authorized facility. You might be able to acquire a filter to knock down 100.3 a little bit, but such things are hard to find (nearly no one uses them in 2020).
 
No, Actually the station i am getting interference from is WHAR (I have hear their top of the hour id when tuned to 105.5), I think their transmitter is located on Hibbs Rd. However, i have also heard another station that i havent Identified.

I am trying to listen to 105.5 and i get the same problem in the same area with 98.7.
I work at a radio station, transmitting about 4mhz away on the spectrum and located in Carteret county, When i know our facility is using our Aux transmitter (lower power), It is also overpowered when i am driving through there as well.

I am listening on my VHF/UHF radio with an FM function B/C my car radio is broke. Would a filter affect VHF/UHF transmissions/reception?

Thanks!
 
OK, so this is second-adjacent interference. The location you have described is outside the protected contour of 105.5 by several miles, so this is expected to a degree.

Most ordinary receivers will start to show second-channel interference when the nearby station is ~25-30 dB stronger than the far station. The FCC's CURVES program suggests along US70 near Newport you're at the 54 dBu contour of WXQR, and the 95 dBu contour of WHAR, a difference of 41 dB, well beyond that rule of thumb.

A filter won't do much (if any) good against second-adjacent interference because the desired frequency and the interfering frequency are so close.

The presence of WHAR, WOTJ, and WLGP all within about 4 miles on that stretch of US 70 will make front-end overload even more likely. And it looks like they are all religious formats!
 
Very interesting. I will have to do some research into this. I like to know the maths behind stuff. I have been wanting to know for a while now, and now i do, that there is nothing i can do!

Thanks for sharing your wisdom!

-EL
 
Wow! You couldn't have picked a worst-case scenario if you tried!

As PTBoardOP94 commented, you're definitely experiencing second-adjacent interference. 3 powerful FM station's transmitters/towers are within a mile or
two from this location you speak of; one of which is only 400khz away from the frequency you're trying to copy; 105.5 WXQR.

The station closest to that frequency, WHAR is an 18.5kw FM at 105.1mhz. The second is 100.3mhz, WLGP a 100kw FM and the third FM is WOTJ 90.7mhz at 24kw.

As stated previously, you're just outside of WXQR's 60dbu curve but literally right in the center of the radiation patterns of all 3 of these radio stations.

I know that's perhaps not what you wanted to hear, but I'm not sure there is anything that can be done to rectify the interference on this stretch of U.S. 70.

It seems in years past, I too recall the interference along that section of US 70 when I was travelling to Morehead City.
 
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