[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?
Yes.
Cheers,
Magnus
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