[time-nuts] Racal 1992

John Green wpxs472 at gmail.com
Thu Aug 27 16:31:50 UTC 2009


Ed Palmer wrote:Which timebase does yours have?  I've got option 4E (similar
to 4B).
Although the timebase appears to be stable, I've noticed that the
counter drifts about 5e-9 during warmup, even when the oscillator has
been on standby for many days.  It takes a couple of hours to settle
down.  Does yours do anything similar?



Ed, Exactly which reference I have seems to be something of a mystery. The
part number on it is 454879. The part number listed in my manual is 404386.
My manual makes no reference to optional timebases. The manual I downloaded
does but doesn't list the part number I have as a choice. Though it is
ovenized, I don't believe it is the best high stability type. It does look
pretty good in general terms. Retrace is important to me and it seems pretty
good in this respect. I did try to
get it in sync with the GPSDO and after several minor adjustments and
several hours of observation, I still saw movement. This isn't that
important as I can always use the GPSDO as a standard.
I did find out why it doesn't output a sine wave. There is a nice sine wave
out of the oscillator itself but that goes through a conditioning amplifier
and into IC39 which is some kind of 40 pin device. IC39 actually feeds the
back panel BNC. Why they do this is beyond me but it answers the question.
I haven't looked at how it behaves coming out of standby yet. I'll let you
know when I have done that.


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