Local Weather Station Attacking Me, wtf?

[RedPenguin]

I don't understand this, but I programmed in many stations from local railroads to my state police.

The railroads are 160-161 and the state police are 154-155.

Normally everything is fine.

Then suddenly, my scanner will stop on a certain channel, usually one of the state police freqs and one rr, and suddenly I will hear modems, then the local weather station 162.4 will blast through, then it will stop, and go back to normal.

This has happened on one state police channel over and over, but only in my house, not when I take it outside for some reason.

It happens sometimes to a RR station but not as much as the state police channel.

I don't even have modems or dialup, so that's funny to hear that from only my house. Also, why would the weather station just come out of no where?

 

[nd5y]

You are hearing intermod. The modem sound is probably digital pager base stations mixing with the NOAA weather radio station. It is a very common problem and there is not much you can do about it without spending a lot of money.

 

[kb2vxa]

Hi Red and all,

Those "modem tones" could be AX25 packet on the 2M Amateur band mixing with the weather station frequency, it's called intermodulation or simply intermod. Why it only happens inside the house I can't explain, it's just another radio mystery. Once in a while I get it from a 2M voice repeater mixing with a local taxi company, no big deal.

Oh, I see Tom jumped the queue (;->) and he could be right too but a pager has a different sound to it. Unless you're familiar you may not know the difference but the effect is the same and just as you described. That prompts me to add that filters are available that will kill the pager and the intermod with it, since it's more likely it's worth a try.

 

[mancow]

Contact Par Electronics. I bet he can build you a nice little 162.400 filter for less than $100.

They work great.

 

[oceans777]

You CAN do something about it, not very expensive

You can install PAR VHF filters easily and they are about $70 each.
I have three installed daisy-chained into my Stridsberg multicoupler - a VHF 152 and 158 and a VHF 162 all centered on local strong frequencies by Dale at Par.

Prior to this I could not scan or search most bands at all. My location is near several very powerful mountian-top antenna farms. 162.55 NOAA wx in particular was bad and 152/158 paging was too - it's all I heard in UHF

Now I can scan/search with no problems and it actually increased my performance quite a bit because the scanner is linear again and not deafened by the local strong signals.
Plus I was able to use a discone mounted on the roof finally.

If you know what the strongest frequencies are that are causing the intermod you can call Dale at PAR Electronics and he will happily build your filter with that as the center frequency. These filters are extremely good and you would be probably be fine if you just order the stock filters without having them centered at your frequency.

Well worth the $. I tried various other filters before learning about PAR and they made no difference at all.

 

[mancow]

Exactly my situation here due to 158.100 paging.

The difference is amazing. I can actually search the Fed band again! It was the best $70 I ever spent for the shack.