Stridsberg FM Notch filter FLT201A still allowing FM Signals?

[CorwinScansNM]

Hi everyone here reading this interesting situation that I am seeing & experiencing with my brand new Stridsberg FM Notch filter FLT201A. I just installed this FM Notch Filter on my Uniden Digital Scanner to try to eliminate all FM Broadcast Signals coming in to my Scanner to help with interference issues on my VHF & UHF programed Frequencies & Band Ranges. After I received this FM Notch Filter today & installed it inside on my LMR400 Coax Cable that goes into my Uniden Digital Scanner from my External Scanner Antenna and then hooked it up to the BNC port on the back on my Scanner, I did a simple no brainer Test to see if the Stridsberg FM Notch filter FLT201A was actually filtering out FM Broadcast Signals from 88 MHz to 108 MHz as I had intended that it should & was supposed to by selecting (Service Search) and then the (FM Broadcast) on my Uniden Digital Scanner?

The results were shocking & looking to be a absolute failure for the specified use/purpose of filtering out the FM Broadcasts of 88 MHz to 108 MHz on my Scanner. This because right away after selecting the FM Broadcast Service Search on my Scanner, it quickly & easily started receiving all FM Radio Broadcast Stations in my area at 3 & 5 Bars of signal receiving coverage & is clearly not at all filtering any of them out or stopping my Digital Scanner from receiving or picking them up?

Now that right there does not seem right to me nor, does it appear that the just installed Stridsberg FM Notch filter FLT201A is even 1% filtering out any of the FM Broadcast Signals to my Uniden Digital Scanner being that I can receive them all at 3 & 5 Signal Bars upon doing an easy & simple no brainer Service Search for (FM Broadcast) directly on my Scanner to test & realize this possible Product fault. Therefore, I am not sure what is wrong or going on here? Maybe I clearly received a non functional or defective Stridsberg FM Notch filter FLT201A that is going to do absolutely nothing on my end for filtering out the 88 MHz to 108 MHz like it is supposed to for $98.00 + $17.00 S&H...

 

[vagrant]

The filter will not "eliminate" FM signals, but it will attenuate the signals. Some people may use two filters in order to attenuate the unwanted signals even further. That posted sweep of the filter claims 25 to 40+ dB of signal reduction which is significant.

While FM broadcast signals can interfere, I actually have more of a problem with paging signals around 152 MHz and utilize filters there as well to tame the interference.

 

[KevinC]

As above, it will attenuate FM broadcast so it no longer causes an issue. If your FM station is coming in at -50 the filter can reduce it to -90, which is still strong enough to receive but not cause an issue.

And I’ve never had an issue with Uniden and FM broadcast as it’s actually a separate “band” in the radio. As opposed to GRE/Whistler where FM broadcast and aero/VHF LMR are the same band so zero filtering.

 

[prcguy]

Yea, what these two guys said. If you had a problem with FM broadcast causing IMD or overload with perhaps a -20dBm signal or two, that filter would reduce it to a point where in most cases it should address the overload or IMD problem. A sensitive receiver would still be able to receive many if not most FM stations in your area even with the filter in line.

If you bought this filter I assume you had a problem that you suspected was caused by a local FM broadcaster. If so try reception with and without the filter and see if its fixing the problem that made you buy the filter in the first place.

 

[abqscan]

Corwin, can you provide any examples of what interference you were recieving and were able to ID them being from the FM radio band?

 

[CorwinScansNM]

Corwin, can you provide any examples of what interference you were recieving and were able to ID them being from the FM radio band?

Not sure at this time.

I do live right below the Sandia Mountains here in New Mexico and was judging & guessing that some of my receiving & or missed Analog Transmissions as well as the high RSSI Levels on my SDS200 Scanner were or might have been caused by high overload of of FM Broadcast Signals coming off the Signal Towers located on the top of Sandia Mountains. Thus is why I purchased the FM Notch Filter to place inline from my Coax Cable before running it into my BCD996P2 as well as my SDS200 for receiving. It was worth a try & I am going to continue to keep it in use & installed for some time just to see if it helps out any even though, I can still pick up all FM Broadcast Stations in my area at 3 to 5 Signal Bars with a simple FM Broadcast Service Search on my BCD996P2.