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FM antenna and a problem

sirianni

sirianni

AK Subscriber
Subscriber
I recently installed a new antenna for my FM tuner. My problem is I have a very powerful FM station in my community that is taking over the entire band. I’m getting into an area that I don’t know a lot about, but somebody said I need a notch filter and their tune to the exact frequency of that station to block it out. Where does one get something like this? It’s above my paygrade any help would be welcome thanks. .
 
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audiotemp said:
Narrowband notch filters do exist for FM but are not common. See this page for some.

I don't know anything about them so this is not a recommendation.
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Also, the problem is that a super-strong station can pop up in multiple places on the dial. Like those old-school Ham Radio guys with illegal transmitting amps and not-so-clean electronics.

I'm not sure a single frequency block will help that situation.
 
The Magnum Dynalab MD-205 Signal Sleuth looks like it can attenuate a single station -30db. If it's still available.

www.magnumdynalab.com

MD 205 Signal Sleuth FM Amplifier

The MD 205 Signal Sleuth FM Amplifier includes a 3 Stage FM tuner amplifier. It is unique because it only amplifies the station you are tuned to up to 30 db. You can also decrease the signal by up to 30 db. If you are experiencing overload from a close radio station. station.
www.magnumdynalab.com www.magnumdynalab.com
 
heyraz said:
The Magnum Dynalab MD-205 Signal Sleuth looks like it can attenuate a single station -30db. If it's still available.

www.magnumdynalab.com

MD 205 Signal Sleuth FM Amplifier

The MD 205 Signal Sleuth FM Amplifier includes a 3 Stage FM tuner amplifier. It is unique because it only amplifies the station you are tuned to up to 30 db. You can also decrease the signal by up to 30 db. If you are experiencing overload from a close radio station. station.
www.magnumdynalab.com www.magnumdynalab.com
Click to expand...
I guess they are available. Though kinda expensive.

He may need to go to a better tuner. One with better rejection of this strong station problem.

I have an old NAD 1600 tuner/pre-amp. It has one of the best tuners I've ever owned. And I had several McIntosh and Marantz tuners before. The NAD can pick up faint out-of-town signals (like from San Diego, Santa Barbara, and Riverside — and I'm in the LA area) without noise or drift. There is no overload problem with strong local stations. This is with an indoor wire dipole antenna.
 
Mr Boochie said:
Also, the problem is that a super-strong station can pop up in multiple places on the dial. Like those old-school Ham Radio guys with illegal transmitting amps and not-so-clean electronics.

I'm not sure a single frequency block will help that situation.
Click to expand...
"Multiple places on the dial" is what happens because a strong signal overloads the input, giving it nonlinear behavior, (usually) not because there are multiple radio frequencies that need to be blocked.
 
Microwave Filter Company. They make a fixed frequency metal tubular notch filter that is the one for serious use. You order to the frequency you need to notch. They come with F male and female at each end so you can just screw it in to the coax feed. Last time I ordered one (a number of years ago), it was about $45 if I remember right. You have to drop them an email from their web site as they don't list exact model on line nor the price. Just ask for the price on a FM broadcast band notch filter. I believe the notch is around 40db or so which is about as good as it gets. It comes with the filter notch frequency listed right on the label.

The variable freq little box ones should do about a 35db notch if half way decent. But you have to have the proper equipment to tune them. Notch filters are so sharp of a notch that tuning by just tweaking may not produce very good results. They are very touchy!

BTW...what is broadcast doesn't appear all up and down the dial. That comes normally from the front end overload or from an external amp being overloaded, which lowering the signal level through a filter will probably cure if it knocks it down enough. If there is an inline amp, take it out first.

EV3
 
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