crystal filter with bessel response sought.

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Article #14909

#14909

From: Bruce Paterson
Date: Mon, 14 Dec 1992 06:47

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A supplier is sought for a multi-pole crystal filter as follows:
Center Frequency: can be chosen to suit at this stage but should be 40MHz
or above - 70 MHz would be very nice.
3dB Bandwidth: 30 kHz (or two filters of 42kHz)
Terminal impedance: The circuit can be adapted to suit, but around 1k Ohm
would be nice.
Ultimate Attenuation: >100dB desired, but some additional LC circuits can
be added to help remove far away spurious responses.
Shape: Bessel - desirably 8 (or more) poles. THIS IS THE HARD PART!

I can easily get equi-ripple type designs but they will not do here.
As I only want a few, a special design is just not economic.
Does anybody know if such a filter is already made?

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Message-ID: <1992Dec14.064721.9705@ips.oz.au>

Path: arc1-ca.pugleaf.net!sparky!uunet!munnari.oz.au!metro!ipso!bruce

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Newsgroups: sci.electronics
Path: arc1-ca.pugleaf.net!sparky!uunet!munnari.oz.au!metro!ipso!bruce
From: bruce@corona.syd.ips.oz.au (Bruce Paterson)
Subject: crystal filter with bessel response sought.
Message-ID: <1992Dec14.064721.9705@ips.oz.au>
Originator: bruce@corona.syd.ips.oz.au
Sender: news@ips.oz.au (Usenet News)
Nntp-Posting-Host: corona.syd.ips.oz.au
Reply-To: bruce@ips.oz.au (Bruce Paterson)
Organization: IPS Radio and Space Services.  Sydney, Australia.
Date: Mon, 14 Dec 1992 06:47:21 GMT
Lines: 13