26 Aug
2003
26 Aug
'03
5:59 p.m.
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.
-tony