[time-nuts] My Racal-Dana 1992

[Charles P. Steinmetz]

It turns out that I unfairly maligned the 1992 (and the 9462 
oscillator, option 04E) when I accused it of poor oscillator 
"settability."  I was inspired by the recent discussions to have 
another crack at mine, and they can, in fact, be set very 
accurately.  One of mine has been reading "000.000000 E-3" for about 
24 hours now, hooked to a Thunderbolt and using the 10-second 
gate.  The other has been toggling between "999.999999 E-3" and 
"000.000000 E-3."  (This is how mine are used --- perpetually reading 
the shop standards to give an independent reality check on their condition.)

Walking the oscillators to 0 is tedious and time-consuming, but not 
difficult.  I think I must not have been sufficiently patient in the 
past.  The fine adjustment has detents -- if you adjust it slowly, 
you can count the clicks.  On both of mine, each click adjusts the 
oscillator frequency about 3 mHz (CW lowers the oscillator 
frequency/raises the displayed frequency).  Interestingly, when you 
are close to zero and adjusting the oscillator only a few clicks at a 
time, it takes off in the opposite direction and peaks at a MUCH 
greater offset than the eventual increment, then returns and 
overshoots in the direction of the adjustment (again, quite a bit 
further than the eventual increment), and finally settles to its new 
value, with another cycle or two of smaller +/- overshoots around the 
final value.  It takes at least 1/2 hour to settle within a count or 
two of the eventual final value, and several hours before you can be 
confident that it has settled to its new value.

Best regards,

Charles