can any one help me identify this part

[radio freak]

Can any tell me what this part is. It reads (55J and has the murata logo on it.It has three pins and is approx. 2mm thick.Below are some pics of the part.

[Acetronics]

455 Khz Ceramic Filter ???

J grade ( = bandwidth )

Alain

[nick_75au]

It may be a ceramic resonator, similar to a crystal used for timing microcontrollers etc, bit of a guess but see how you go.
just looked at the murata website quickly 55j doesnt come up in serches but it does look like a ceramic resonator.
Regards
Nick

[radio freak]

455 Khz Ceramic Filter ???

J grade ( = bandwidth )

Alain

Can this be used as a ceramic filter in an rc receiver??

[Acetronics]

Can this be used as a ceramic filter in an rc receiver??

Of course !!!

Alain

[radio freak]

Of course !!!

Alain


Can you please help me out with the pin identification

[radio freak]

Is there no one who can help me identify the pins on this ceramic filter??

[Eric_N57105]

Is there no one who can help me identify the pins on this ceramic filter??

From the orientation in your photo, the pins are USUALLY Input, Ground, Output. However, it doesn't always matter as they are symmetrical designs.

My guess is also that it is a 455khz ceramic filter. If you have a kilobuck spectrum analyzer sitting in a dusty corner of your garage, it is a simple matter to test it and check its response. If not there are some relatively easy test methods based on using a software audio spectrum analyzer like Spectrogram.

Here's a link to get you started. It is a procedure for adjusting filters in an Elecraft amateur radio transceiver. Most of the details will be meaningless, but it should give you an idea of the technique which you can easily adapt to testing ceramic or crystal filters.

http://www.elecraft.com/Apps/new_fil_docs/filter_apps.htm

Google Spectrogram as well and you will find a lot of similar articles. It's a great tool for receiver design. Cool Edit is another one that works well for me.

Eric

[radio freak]

Hello and thanks to everyone who tried to help me out. I found the part and I am attaching a PDF link for future reference for everyone.






P.S.The murata manual says filters for AM use, does this mean they cannot be used on an FM receiver??

[Eric_N57105]

Hello and thanks to everyone who tried to help me out. I found the part and I am attaching a PDF link for future reference for everyone.

P.S.The murata manual says filters for AM use, does this mean they cannot be used on an FM receiver??

No. Generally, AM radios use a 455khz IF and have bandwidths of around 6 khz. FM radios normally use a 10.7 mhz IF and have wider bandwidths. Even narrow band FM is more than twice as wide as AM. You can see that in their specs.

So, generally, the AM ceramic filter is going to be more selective, i.e. better at rejecting adjacent channel interference which is a good thing for an RC receiver.

Eric

[vintage1]

Narrow band FM such as we use uses 455KHz filters just like AM. The bandwidth is similar. Well actually in the USA the channels spacing is 10KHz whereas AM radio is 9KHz.

UK spacing is IIRC 20Khz.

10.7 MHz filters are used in broadcast FM (400 KHZ bandwidth) and the the first IF of dual conversion receivers.

[radio freak]

thanks for the info people :)