[time-nuts] External Frequency Standard Inputs on Counters

Magnus Danielson magnus at rubidium.dyndns.org
Fri Apr 3 07:16:14 UTC 2009

Ed Palmer skrev:
> I see that on many counters (e.g. SR620, HP 5370, HP 5372) the external 
> frequency standard input has an impedance of 1Kohm.  Why such a high 
> value?  Are they implying that it's acceptable to daisy-chain a single 
> reference to multiple devices like an old 10Base2 ethernet network?  

You can do that. If you have a larger setup you can avoid a distribution 
amplifier, but having one provides you with the isolation that hubs to 
for basically the same reason.

> Should such a link be terminated in 50 ohms like a 10Base2 network?



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