[time-nuts] My Racal-Dana 1992

[Ken , VK7KRJ]

If the variable capacitor in question has ball bearings, it's probable that the bearing is 
a bit tight and the races have indented. This gives the effect of a detent.

On 2011-12-19 01:17, Ed Palmer wrote:
> 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
>>

-- 
Cheers, Ken
vk7krj at users.tasmanet.com.au
www.vk7krj.com

'It seems hard to sneak a look at God's cards. But that He plays dice and uses
"telepathic" methods .... is something that I cannot believe for a single
moment.'     (Einstein's famous quote on Quantum theory)


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