[time-nuts] My Racal-Dana 1992

Ed Palmer ed_palmer at sasktel.net
Sun Dec 18 09:17:11 EST 2011


I haven't seen a capacitor with detents.  Could the fine adjustment be a 
multi-turn pot?  I've seen detents with those.  I looked at mine but 
couldn't tell.  A pot would mean voltage control.  Maybe we could build 
a GPSDC (GPS Disciplined Counter).  Yes, I'm kidding.  I think.....

Ed


On 12/18/2011 1:21 AM, Charles P. Steinmetz wrote:
> 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
>




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