Thanks for the info Antonio. Racal didn't spec the warmup
characteristics of the counter as a whole and it seemed a little odd
that the warmup drift for the counter was as large as 10 days of
oscillator drift.
Ed
[email protected] wrote:
I have two 1992, and actually one has to terminate the output to see the real
waveform.
They have both the 04E option, that I believe is a nice one. In long term
measurements, I've found that mine have an aging rate in the range of 1x10E-10
per day, or better (compared to Rb). The crystal is cut to 5 MHz, then doubled.
The time required to stabilize after power on is normal.
Antonio I8IOV
My 1992 has a similarly ugly reference output - until I terminate it.
Then it's a fairly nice square wave between 0 and 1 volt. Rise & fall
times are in the range of 5 ns. The manual doesn't state what the wave
shape is, only that it's > 600 mVp-p into 50 ohms. I have a brochure
that says "TTL levels giving approx. 1Vp-p into 50 ohms". My phase
measurements also have a similar amount of 'noise' to yours.
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
John Green wrote:
Just acquired a used 1992 off eBay. Excellent, almost like new with manual
and even spare fuses. I noticed that the internal reference's waveform is
more like a nasty sawtooth than a nice sine wave. Is that normal? Also, when
I hook my GPSDO through a two way splitter and two different length cables
and measure phase, I get a +\- 3 LSD ambiguity. Is that about right?
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