[time-nuts] 5 and 10 MHz crystal filters

Alan Melia alan.melia at btinternet.com
Mon Nov 15 18:42:39 UTC 2010


Hi John I have a collection of filters but I have not seen any common ones
at those frequencies with 50 ohm termination. The characteristic would
probably require transformer input and output coupling, the inherent
impedance of most filers in this frequency range will be around 1kohm. The
narrower the lower the impedance.

Those crystal frequencies are available relatively cheaply it should be
possible to make a ladder filter with some form of matching to 50 ohms quite
simply. There are lots of references around (the recent QEX has on on
overtone crystals, but does reference some of the articles on fundamental
crystal filters.)

Alan G3NYK

----- Original Message ----- 
From: "John Ackermann N8UR" <jra at febo.com>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Monday, November 15, 2010 3:44 PM
Subject: [time-nuts] 5 and 10 MHz crystal filters


> I'd like to find a couple of 5.0 and/or 10.0 MHz crystal filters,
> preferably configured for use in-line with 50 ohm coax.
>
> I've done some googling but don't find anyone selling these as a stock
> item.  Do they exist?  Any pointers would be appreciated.  Used/surplus
> is fine (even preferable).
>
> Thanks!
>
> John
>
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