The 8640B external reference can be configured to accept a 1MHz input,
but the jumpers are deeply buried in the time-base module on A8A3.
It is not necessary for the reference to be a sinusoid. It is first
attenuated and then amplified before being fed into a logic gate,
which feeds the counter chain.
The internal oscillator always runs and there can be some weak
crosstalk that beats the internal with the external reference, which
can show up when they are very close in frequency as very close-in
spurs.
73, Ed, K1GGI
--- In hp_agilent_equipment@..., "Richard W. Solomon"
<w1ksz@...> wrote:
So basically what you are telling me is that it is not worth the
effort to try and supply
an external reference to the 8640B, yes ??
I have two TrueTime XL-AK GPS Receivers that have 5 outputs on the
rear, internally selectable
for 10, 1, .1, .01 MHz and 1 pps outputs. I guess I'll just use one
to supply the counters.
Thanks for the replies.
73, Dick, W1KSZ/7
