[time-nuts] 10 MHz clock distribution for the lab
Charles P. Steinmetz
charles_steinmetz at lavabit.com
Sun Apr 21 18:55:38 UTC 2013
Russ wrote:
>The HP 5334B has a 1k Ohm input impedance shunted by <20 pf it
>wouldn't hurt to terminate this input
This is pretty typical for reference inputs on test equipment. The
idea is that one 50 ohm source can feed a number of instruments using
nothing but a series of Tee connectors, with the far end of the cable
terminated in 50 ohms. The 1k loads will cause little disturbance on
the 50 ohm line.
If best isolation and delay matching are required, the source should
feed a good DA and there should be equal-length runs of coax from the
DA to each instrument, with proper terminations. Generally, this is
required only for measurement inputs -- it is rarely necessary for
the references of different instruments to be phase coherent (and
different instruments are likely to have quite different internal
reference delays).
Best regards,
Charles
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