PSR500/PSR600: heard on other frequency

scanmanmi · Oct 8, 2017

My scanner stopped at 257.05 on some muffled noises on AM mode. I found it was a grabled 94.5 FM. I subtracted them and came up with 162.55. There is a nearby weather station on 162.525 though. I have heard voices on some wierd freqs like 166 or 171 or something like that. What up?

ScannerSK · Oct 8, 2017

scanmanmi said:
My scanner stopped at 257.05 on some muffled noises on AM mode. I found it was a grabled 94.5 FM. I subtracted them and came up with 162.55. There is a nearby weather station on 162.525 though. I have heard voices on some wierd freqs like 166 or 171 or something like that. What up?

That sounds like intermodulation to me. The following article explains it somewhat:
Wiki on Intermodulation

Shawn

Ubbe · Oct 9, 2017

You could probably solve it by using a FM trap filter. If you use the BNC rubber antenna you could look out for fliters that has BNC male-female, like the super expensive one from Stridsberg.

/Ubbe

krokus · Oct 9, 2017

scanmanmi said:
My scanner stopped at 257.05 on some muffled noises on AM mode. I found it was a grabled 94.5 FM. I subtracted them and came up with 162.55. There is a nearby weather station on 162.525 though. I have heard voices on some wierd freqs like 166 or 171 or something like that. What up?

Most radios use 10.7 MHz as an IF, which gives you a 21.4 MHz offest image possibility, too. Is there a military user, on 141.15 MHz, nearby?

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737mech · Oct 11, 2017

Plus one FM Trap

I think you will really really like your scanner if you decide to install an fm trap. Good ones are available from Dale at Parelectronics or you can try a cheap one from Radioshack. Try it, you will finally hear what you've been missing out on.

vagrant · Oct 13, 2017

I am a fan of PAR filters and and have four different ones. I also use a Radio Shack FM filter and this particular combined notch filter that is for AM & FM. HPN-30118 Combined Notch Filter | Scanner Master

In particular, I use that combined notch filter on the scanner in my vehicle. The filters I use are worth every penny and resolve RFI issues I have, some of which I cause myself.

scanmanmi · Oct 13, 2017

I will get a trap. I am starting to listen to Air band and was wondering if they attenuate those freq inadvertently.

Ubbe · Oct 14, 2017

scanmanmi said:
I will get a trap. I am starting to listen to Air band and was wondering if they attenuate those freq inadvertently.

Yes, they do.

You have to look at filters specificly made for airband monitoring. They usually trim the attenuation curve 10MHz lower or do not attenuate as deep in the FM broadcast range.

/Ubbe

PSR500/PSR600: heard on other frequency

scanmanmi

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ScannerSK

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Ubbe

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krokus

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737mech

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vagrant

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scanmanmi

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Ubbe

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