Looking for Specialty Crystal Filter, Please Help
 

I am currently looking for a crystal filter in the CF range of 70 to
100MHz. I know that these are rare and are not standard for FM radio,
citizen's band, etc, but it would be most helpful for me to find one.
Ideally, the filter should have a passpand of +/-3.75kHz about the CF
(3dB). I've checked numerous manuf. who make these type of crystal
filters (FOX, ILSI, Raltron, MCF, etc) but most of their products are
vapor ware and have never been fabricated. Do any of you have a
suggestion of where I might find a filter that meets this spec? My goal
is to avoid another IF stage in my hardware...this is why I require the
narrow bandwidth at the high CF. Even if you have a suggestion of where
I might find a 70 to 100 MHz CF filter with a wider bandwidth I would
appreciate it very much.

Thanks for the help.

ZenSafari wrote:

I am currently looking for a crystal filter in the CF range of 70 to
100MHz. I know that these are rare and are not standard for FM radio,
citizen's band, etc, but it would be most helpful for me to find one.
Ideally, the filter should have a passpand of +/-3.75kHz about the CF
(3dB). I've checked numerous manuf. who make these type of crystal
filters (FOX, ILSI, Raltron, MCF, etc) but most of their products are
vapor ware and have never been fabricated. Do any of you have a
suggestion of where I might find a filter that meets this spec? My goal
is to avoid another IF stage in my hardware...this is why I require the
narrow bandwidth at the high CF. Even if you have a suggestion of where
I might find a 70 to 100 MHz CF filter with a wider bandwidth I would
appreciate it very much.

Thanks for the help.


The only off the shelf 70 MHz CF filters I've seen were used in
Satellite TV or Telemetry receivers. Microdyne built their own IF
filters For narrow frequencies like this, with switching to select one
of up to 12 internal bandwidths, and a few models allowed 12 external
filters, as well. The SAW filters for Satellite receivers is generally
+/- 10 MHz, so those won't help you. Its too bad, because there are old
C-band and early KU band junkers almost everywhere.

--
http://home.earthlink.net/~computersforvets/

Michael A. Terrell
Central Florida

In article .com,
"ZenSafari" wrote:

I am currently looking for a crystal filter in the CF range of 70 to
100MHz. I know that these are rare and are not standard for FM radio,
citizen's band, etc, but it would be most helpful for me to find one.
Ideally, the filter should have a passpand of +/-3.75kHz about the CF
(3dB). I've checked numerous manuf. who make these type of crystal
filters (FOX, ILSI, Raltron, MCF, etc) but most of their products are
vapor ware and have never been fabricated. Do any of you have a
suggestion of where I might find a filter that meets this spec? My goal
is to avoid another IF stage in my hardware

Chris-

I recall such a product from about 25 years ago, but for the 155-165 MHz
range and somewhat wider bandwidth. It was from:

PTI - Piezo Technology, Inc.
http://www.piezotech.com/
2525 Shader Road
Orlando, FL 32804 USA
Phone: 407-298-2000
Fax: 407-293-2979

It might be worth contacting them, in case they still make the filters,
and can make them for your frequencies and bandwidth.

73, Fred, K4DII

ZenSafari wrote:

I am currently looking for a crystal filter in the CF range of 70 to
100MHz. I know that these are rare and are not standard for FM radio,
citizen's band, etc, but it would be most helpful for me to find one.
Ideally, the filter should have a passpand of +/-3.75kHz about the CF
(3dB). I've checked numerous manuf. who make these type of crystal
filters (FOX, ILSI, Raltron, MCF, etc) but most of their products are
vapor ware and have never been fabricated. Do any of you have a
suggestion of where I might find a filter that meets this spec? My goal
is to avoid another IF stage in my hardware...this is why I require the
narrow bandwidth at the high CF. Even if you have a suggestion of where
I might find a 70 to 100 MHz CF filter with a wider bandwidth I would
appreciate it very much.

I have a couple of the Ten Tec filters that were used in their Paragon
transceiver. 70 MHz center frequency, don't remember the bandwidth but could
measure one. Or you could check with Ten Tec and if it fits your
requirements, they're available.

W4ZCB

Thank you all for your replies. These leads are extremely helpful to
me. I will look into some of these options and get back to you.

Again, thanks for your input.

-Chris

"ZenSafari" wrote in message
oups.com...

Thank you all for your replies. These leads are extremely helpful to
me. I will look into some of these options and get back to you.

I think we would all be interested in what you discover. My own reaction is
that you're not going to find something that narrow at that IF, but if you
do, it might be useful in other contexts.

...

the aircraft navigation marker beacon band is 75 MHz and there were
many crystal filters make with a 75 MHz CF and a BW of maybe 20 kHz or
so.

you may be able to find one.

Mark