[time-nuts] Methods for comparing oscillators

[Rick Karlquist]

Magnus Danielson wrote:
>> - a 10811-class OXCO tuned to generate beat notes of several Hz

On the 10811 production line, they had some 10811's with specially
made crystals in them that had a 500 Hz offset.  These were
used to test for short term stability with a 500 Hz beat note,
using the HP 5390 system.  The offset oscillators
themselves were verified for short term stability by a round robin
method.  The trouble with this method is that there was no
way to find the 10811's with the best stability, since all good
ones were just "at least as good as the offset oscillator".
Since the offset oscillators were limited quantity specials,
there was no way to select for good stability.

I volunteered to management to build a really high quality
synthesizer to replace the offset 10811's.  However, they
never took me up on it.

I think the general opinion was that you couldn't get away
with a beat note of a few Hz as could be achieved by pulling
a standard crystal.

Rick Karlquist N6RK