[time-nuts] External Frequency Standard Inputs on Counters

Magnus Danielson magnus at rubidium.dyndns.org
Fri Apr 3 18:57:38 UTC 2009


John Ackermann N8UR skrev:
> I think you guessed it, Ed.  There are a number of applications where 
> you want to drive at least two devices from the same reference so using 
> a moderate input impedance facilitates that.
> 
> I've done some goofy things like trying to drive 3 or more 5334A 
> counters or 3586C VLF receivers from a single reference.  My feeling as 
> a result is that you can safely daisychain two devices, but three may be 
> tricky.
> 
> Ideally, you should terminate the end of the chain with 50 ohms, but 
> depending on the drive level you might not be able to get away with that.

Not terminating could create a null at or near one of them... thus 
resulting in no input signal for that box. Overcoming that would require 
more drive level than the other boxes wants...

Cheers,
Magnus



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