[time-nuts] My Racal-Dana 1992
Ed Palmer
ed_palmer at sasktel.net
Sun Dec 18 14:17:11 UTC 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
>
More information about the time-nuts
mailing list