[time-nuts] 10 MHz Band-Pass Filter Needed
John Ackermann N8UR
jra at febo.com
Thu Jan 8 18:30:22 UTC 2009
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 !!
> 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.
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