Trouble with HP 59309A Digital Clock

From: Tony Duell <>
Date: Tue Aug 26 17:59:00 2003

> a) What does the INT/EXT switch do? My machine appears to work only when the
> switch is in the INT position.

Probably for the master clock oscillator. HP intruments that need an
accurate master clock (real time clocks, frequency counters, etc) have a
reasonably good INTernal clock (crystal, possibly oven-stabilised), and
an input for an external clock (often 10MHz) from, say, an atomic beam
standard (!).

If you set that switch to EXT, then there's no clock signal. This may
well be the clock for the control logic too, so it might not even respond
to the HPIB interface at all.

Received on Tue Aug 26 2003 - 17:59:00 BST

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