I need a filter for my scanner...

[verbatim]

I have a radioshack pro-82 scanner and yagi antenna outdoor in a 6 mts mastil for hear air band frequency but i have fm interference from a station in 103.75 Mhz (new station in the dial) from 118.0 up to 128.5 MHz.

I been reading about filters: notch filters and band pass filters. I have intent to buy one, but i do not know which...

I been seeing in www.scannermaster.com two options:  http://www.scannermaster.com/BPF_AIR_Air_Band_Band_Pass_Filter_p/24-531022.htm  and  http://www.scannermaster.com/HPN_30118_Combined_Notch_Filter_p/24-531024.htm

the price is equal in both and more cheap than  http://www.scannermaster.com/Jim_96XI_1_Adjustable_Notch_Filter_p/36-531260.htm  or  http://www.scannermaster.com/Jim_ABF_0604_Air_Band_Filter_p/36-531261.htm


Which do you recommend me? Which is the best?

I live in Mexico and i will try to buy by internet in www.scannermaster.com and that they send me the product i hope that arrive here

thx

[Squawk 7700]

Hi verbatim,

I use both of these filters and they both work equally well,
http://www.scannermaster.com/HPN_30118_Combined_Notch_Filter_p/24-531024.htm
and http://www.scannermaster.com/Jim_ABF_0604_Air_Band_Filter_p/36-531261.htm

A side by side comparison is hard to tell the difference between the two filters listed above, they both effectively reject FM interference in my opinion. The HPN-30118 also will reduce signals below 30Mhz.
I have 3 of these and happy with them.

I modified the Jim ABF 0604 with f connectors. If your curious, here is a picture of the inside.
http://www.flickr.com/photos/34848377@N07/3477299388/in/photostream/

Hope this info helps? I do know from experience that FM broadcasters to cause havoc on the Airband
frequencies, and these filters do help with reception.

Ken

[verbatim]

Thanks for the information.

I really wanted to know the opinion of those peoples who have used any of these filters and know if they work very well or not.

Thanks also for photography, I thought the filter had more things inside. It is interesting to your modification. Do you use F connectors instead of BNC in antenna and scanner? What type of coax do you use?

Will you have another picture more inclined to view more detail the internal connections of the coils?

The Jim ABF Filter is not in stock in the page www.scannermaster.com so I think purchases the notch filter.

thx Ken


Does anyone else have other experiences with these filters?

[dave]

I would only add that you need to understand why you want to add a filter.  In general it is a good idea for interference rejection, but if you live far away from known interference sources the filter only adds additional loss (although small) into your system.  If you are in a fringe reception area that could be just enough to cause you to lose some weak signals.

If you hear interference, try to determine where it may be coming from.  If it is a radio station, you can usually identify the station by tuning your AM/FM radio around to compare the interfering audio to local AM/FM stations.  If it is a paging transmitter, then there is no use in identifying it - just slap a bandpass filter on and it *should* get rid of it, unless the paging transmitter is very close.  

Hope this helps.  All of those ScannerMaster filters work well.

Dave

[verbatim]

Thanks Dave, Nice to meet you

I live in a residential development out the city; 7 miles from the airport and 3 miles of the city where the new FM station is. (There was only one FM station in that city)

At first I was not interference in the band aerial, the signal was clean, but when it appeared the new FM station began interference.

Now the scanner is connected to another J-pole antenna two meters above the ground, but if I go up higher, I will again hear the interference. This made the reception of the control tower is poor.

So I think that if I install a filter could help me eliminate any interference, and my antenna could be higher.

I understand that by introducing a filter will have an insertion loss, but I hope to be minimal. (<1 db)

The FM station is already identified, the frequency is 103.7 MHz

With your help I can take  better purchasing decision, especially because it is an international purchase for me.

Thanks to all ... (sorry my english)

[dave]

Then this is the one that you want:

http://www.scannermaster.com/HPN_30118_Combined_Notch_Filter_p/24-531024.htm

[verbatim]

Thanks Dave, I'll buy that filter. I will comment my experiences after.

[Squawk 7700]

I highly recommend the filter Dave suggested above. The HPN-30118 is very effective.

I took one apart a few years ago and modified it with an F type connector, here is what the inside looks like. http://www.flickr.com/photos/34848377@N07/4627507069/sizes/l/

Ken

[verbatim]

thanks for the photo Squawk 7700, it's very interesting what they have inside.
Do You have the values of the blue components?

Does the F is the input connector and BNC connector is the output?
thanks

[Squawk 7700]

blue caps have 47 printed on them.
It works either way. I have the BNC going to the antenna and the F connector going to the radios.
It's easier to just get a BNC to F adapter at Radio Shack if needed rather than opening up the component and desoldering parts and the lid.

You can make your own FM band notch filter. It takes 6 turns of #16 AWG solid copper wire around a 6mm diameter form in series with a 2-20 pF variable capacitor. (My next project?)

Ken

[verbatim]

hello friends

At last I have in my possession my new filter Airband BPF-AIR here in mexico from scannermaster. I finally decided on this model because it also had interference from the police band and since I only hear the band aerial, so I decided well, I wanted to remove all interference.

I am impressed with its operation. It has eliminated the interference from FM radio station. Now I hear the sound clearer.

Thank you all for your comments and experiences.

Thanks Dave

[Squawk 7700]

Glad the filter worked out for you 

Ken

[verbatim]

me too jeje

thx Ken

Certainly  I saw pictures of your yagi antenna in your album Flirck, cool!!

[Caleb]

I was having the same exact problem!!! Except I had 100.1 radio station, and the smooth jazz was really boring me haha!!!   

Got a FM trap for $2.69, and it fixed it!

http://www.mcmelectronics.com/product/33-341&CAWELAID=220403171

[verbatim]

Hello Caleb

I see that your filter is very cheap in comparison with mine and also work. The problem is that here in Mexico there are no such filters.

I will look for information about the filter you mention on the internet to see how this built. If you have pictures of his internal parts, I would appreciate very much.

Regards

[verbatim]

hi caleb

I tried to say "do not sell in Mexico the FM trap" and only interested me as your filter is constructed so I asked if you had photos of internal parts.

The filter that I bought works exactly what I need.

and now this say in the mcmelectronics.com web page:

Do you ship outside of the United States and Canada?  MCM ships to North America including the 48 contiguous states, Alaska, Hawaii, Puerto Rico, Canada, and the United Kingdom. Please call our customer service department at 1-877-626-3532 or email us at talk@mcmelectronics.com with any questions.

I think they not sent to Mexico

thx

[verbatim]

don't worry. caleb   

regards

pd. have pictures of internal parts of fm trap? 

[Caleb]

don't worry. caleb   

regards

pd. have pictures of internal parts of fm trap? 

Nope, don't have any. Hopefully I don't find out either haha!