Why am I picking up Radio Station WRMF 97.9 MHz on 29.2 MHz

[dragon48]

Not sure where to post this. Mods, please move if appropriate.

I dusted off my SDR and am playing around. In WFM mode, on 29.2 MHZ, I'm picking up WRMF, a local, strong (100,000 watts) radio station that broadcasts on 97.9 MHZ. Can somebody please explain this?

 

[a417]

the cheap SDRs have **** front ends.

They overload easily.

You're seeing/hearing an image.

 

[a417]

I have a flamethrower less than 1500' from my house, totally understand. Dial the gain way the hell back and invest in a broadcast FM trap. They're very simple to make (dead bug style if you can't do it on protoboard, even) and the instructions and parts lists are available on line.

You could even buy one if you wanted, but where's the fun in that?

 

[dragon48]

the cheap SDRs have **** front ends.

They overload easily.

You're seeing/hearing an image.

Confirmed it's unique to the SDR. I don't pick up the station on 29.2 on one of my radios.

I have a flamethrower less than 1500' from my house, totally understand. Dial the gain way the hell back and invest in a broadcast FM trap. They're very simple to make (dead bug style if you can't do it on protoboard, even) and the instructions and parts lists are available on line.

You could even buy one if you wanted, but where's the fun in that?

I'm an OK hacker and would love to build one, but I don't have a proper workspace right now. While I have your attention, is this appropriate?

https://www.amazon.com/Flamingo-FM-Applications-Problematic-SMA-Connected/dp/B07XKY8YKB

 

[a417]

That will help.

 

[a417]

You may also be in a situation where you need less antenna.

 

[MStep]

Sub-harmonics?

 

[nd5y]

Sub-harmonics?

No, because it doesn't exist.

 

[W2SOX]

As a417 said broadcast trap will help 10 fold. My SDR was unusable until I invested in one, like you I got FM stations all down scope.

 

[dragon48]

I just purchased one. As soon as it find it in one of my many bags of electronics, I'm going to hook up my upconverter. Where does the broadcast trap go in the chain. I assume I put it between the antenna and the SDR, and then I connect the upconverter. Please verify this is the correct setup.

Ty

 

[W2SOX]

I just purchased one. As soon as it find it in one of my many bags of electronics, I'm going to hook up my upconverter. Where does the broadcast trap go in the chain. I assume I put it between the antenna and the SDR, and then I connect the upconverter. Please verify this is the correct setup.

Ty

Correct it should placed between the SDR and the Antenna.

 

[F1RFK]

you can use this :

HB9AMO - Coaxial FM band notch filter

HB9AMO web site

www.hb9amo.net

 

[dragon48]

you can use this :

HB9AMO - Coaxial FM band notch filter

HB9AMO web site

www.hb9amo.net

Thanks, but I threw $21.95 at the problem and bought this - https://www.amazon.com/gp/product/B07XKY8YKB/

 

[dragon48]

@a417 - The filter I purchased on Amazon works. I no longer pick up the image. Many thanks!