[time-nuts] My Racal-Dana 1992

Ed Palmer ed_palmer at sasktel.net
Sun Dec 18 14:05:54 EST 2011


On 12/18/2011 12:00 PM, Charles P. Steinmetz wrote:
> Ed wrote:
>
>> My 04E must be less stable than yours.  I was monitoring a fully 
>> warmed-up Efratom FRK rubidium and saw a drift of ~ 0.04 Hz (i.e. 40 
>> counts) over two hours after I turned on my 1992 from standby.  Are 
>> more than one type of oscillator used for option 04E?  Mine is a 
>> model 9462.
>
> There are actually two Racal part numbers that you sometimes see in 
> documentation as being used for Option 04E -- 404386 and 454879.  The 
> 9462s in the US military contract 1992s that I have seen (pretty much 
> all of the 1992s one sees in the US are from the mil contract, IME) 
> are marked "9462 454879."  I have not seen an oscillator marked 
> "404386," so I do not know if these are Model 9462 oscillators or 
> another model.

Mine is marked "9462 454879 Rev A"

> As with any crystal oscillator, there is no doubt a range of both 
> stability and warm-up drift in the 9462s you find, but IME not a very 
> large variation.  (I'm assuming that you clocked the warmup after the 
> 1992 had been in standby -- plugged in with the red power button "on" 
> -- for a week or more [preferably for a month or more].)

Yes, mine was always in standby mode.  It was probably running for many 
months like that.

> An oscillator with greater warm-up drift will not necessarily be less 
> stable, after warmup, than one with less warm-up drift.

Agreed.  But it was annoying to leave it in standby mode and then still 
have some drift.  At first, I thought the drift was due to the rest of 
the unit warming up.  I was quite surprised when my tests showed that 
the drift was 100% due to the oscillator.  Using an FRK as an external 
reference, I can turn on my 1992 (not from standby) and immediately 
measure my Z3801A as 10.000 000 000 MHz.

Ed





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