[time-nuts] 10 MHz Band-Pass Filter Needed

[Lux, James P]

James Lux, P.E.
Task Manager, SOMD Software Defined Radios
Flight Communications Systems Section
Jet Propulsion Laboratory
4800 Oak Grove Drive, Mail Stop 161-213
Pasadena, CA, 91109
+1(818)354-2075 phone
+1(818)393-6875 fax

> -----Original Message-----
> From: time-nuts-bounces at febo.com
> [mailto:time-nuts-bounces at febo.com] On Behalf Of John Ackermann N8UR
> Sent: Thursday, January 08, 2009 10:30 AM
> To: danrae at verizon.net; Discussion of precise time and
> frequency measurement
> Subject: Re: [time-nuts] 10 MHz Band-Pass Filter Needed
>
> Dan Rae wrote:
> > Richard W. Solomon wrote:
> >> The GPSDO I want to use has an output rich in harmonics. In some
> >> cases that is good, but Murphy rules and in the application I have
> >> today, it is not good.
> >>
> >> I need a 10 MHz Band-Pass Filter, Bandwidth is not critical,
> >> something small with SMA connectors would be ideal, but I
> can live with BNC.
> >>
> >> Anyone have such a beast or know where I can get one ? I checked
> >> Mini-Circuits and choked on the price !!

You mean the ever popular BBP-10.7 for $41?
Hard to beat that price for something comparable.


> >>
> >>
> >
> > Dick, it is really easy to build one.  The wonderful (free!) filter
> > design program ELSIE will give you all the help you need.  I would
> > have thought an hour or so with a couple of toroids would do the
> > trick.  Even just a Low Pass filter would usually do to
> turn a square wave into a sine...
>
> It's actually much better to use an LPF than a bandpass
> filter if you don't have subharmonic energy to deal with.  An
> LPF with a cutoff midway between the fundamental and the 2nd
> harmonic will show much less tempco (in the form of phase
> shift over temperature) than a bandpass filter.

You might even be able to use some wonky little filter feedthrough with a suitable cutoff frequency.