[time-nuts] Crystal filters in test equipment

[Bob kb8tq]

Hi

Narrowband filters have significant amounts of delay. Any change in that delay (like from
temperature or ……) will phase modulate the oscillator. Conventional wisdom these days
is that your ADEV will be better without the filter. 

Phase noise wise, you can only get just so close to the … errr …. noise floor. That moves 
you in the direction of a filter that can handle a bit of power. That takes you out of the “cheap 
filter” part of the world …. 

Bob

> On Mar 26, 2020, at 6:03 PM, Perry Sandeen via time-nuts <time-nuts at lists.febo.com> wrote:
> 
> Learned Gentlemen,
> Both the HP 106 and 107 have a post oscillator crystal filter.  There is also a 10 MHz crystal filter used in my Tracor 527E FDM.
> So the question I have is there anything to be gained by adding 10 MHz crystal filters to the 10811 and similar OCXO's?  They are very inexpensive to purchase.
> Regards,
> Perrier
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