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

[John Ackermann N8UR]

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.

John