[time-nuts] My Racal-Dana 1992

David C. Partridge david.partridge at perdrix.co.uk
Fri Dec 16 14:24:49 EST 2011


>1.  You can get a 10 sec. gate time and therefore .001 Hz resolution at 10 MHz by holding the 'up arrow' key for about 2 sec.  It's in the manual, once.  If you blink you miss it.

What page please - I never spotted that ...

Regards,
David Partridge
-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Ed Palmer
Sent: 16 December 2011 18:09
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] My Racal-Dana 1992

I bought a 1992 a few years ago and I've been quite happy with it.  It does have a few quirks, of course.  Some good, some bad.

1.  You can get a 10 sec. gate time and therefore .001 Hz resolution at 10 MHz by holding the 'up arrow' key for about 2 sec.  It's in the manual, once.  If you blink you miss it.

2.  Even a completely warmed-up 04E oscillator drifts after the unit is turned on from standby mode.  However, if you use an external reference, you can turn the unit on and immediately start measuring to .001 Hz with no drift.  I tried removing the oscillator completely, but it also provides the clock for the microprocessor so it has to be present.  The changeover to the external reference only happens after the processor detects the presence of the external reference.

3.  My 1992 doesn't perform properly when the power glitches.  Even on a UPS, the transfer time is long enough that the 1992 resets.  The linear power supply appears to be working correctly and the capacitors are good, but it just doesn't have enough headroom to handle the transfer.

4.  I have one unit with bad switches and one with good ones.  The body on the good switches is white, the bad ones are black.  I don't know if this is the same on all units or not.  You can see the body if you pull a keycap off.  No disassembly required.

Ed



On 12/16/2011 11:31 AM, Larry McDavid wrote:
> Chuck, I have a Racal 1992 with exactly the same government label on 
> its side as in your picture, except that my ink-stamped warranty date 
> is a few days later than the date on your counter/timer. These must 
> have come from a large government contract order.
>
> However, while counting the 10 MHz from my HP Z3801A and displaying 
> 0.01 Hz resolution on my 1992, I can rap very smartly indeed with my 
> knuckles on the outside of the counter case (anywhere) and not change 
> the displayed count. Further, my counter seem insensitive to 
> orientation or motion. Of course, I can see only to 0.01 Hz resolution 
> at 10 MHz.
>
> I just recently got this 1992 and have not yet tried to adjust its 
> Option 04E ocxo (the Racal 9462) so I don't know if my unit exhibits 
> the same cat-herding issue as yours. Judging from the condition of my 
> 1992, I doubt it was used much. Mine looks new; it had plastic caps on 
> all the BNC connectors and those connectors are all bright and shiny. 
> My unit had a calibration-due date of 9/26/2011; it may not have been 
> used since that calibration just over a year ago. At present, I'm 
> letting it run to see if there will be short term drift or room 
> temperature sensitivity of its ocxo. Later, I'll do what you have done 
> to evaluate long-term drift more critically.
>
> I also have a Racal 1999 10-digit counter that counts to over 3 GHz. I 
> like these compact counters! I'm using a TADD-1 to distribute the 10 
> MHz from the Z3801A to five devices so the ocxo performance is 
> important only if I use them portable.
>
> How many TimeNuts have the Racal 1992 and what is your experience? 
> Yes, I've heard of push button switch issues but so far I've not 
> encountered any myself.
>
> Larry W6FUB
>
>
> On 12/16/2011 3:19 AM, Chuck Forsberg WA7KGX N2469R wrote:
>> Has a 9462 oscillator module in it.
>> I've been fooling with little C hacks to make freq and phase
>> measurements via GPIB.
>>
>> In my desire to super-tweek the timebase I discovered that small
>> adjustments take
>> many minutes to settle down. It's like herding cats.
>>
>> I noticed that physical shocks would randomize the frequency over a 10
>> Hz range
>> at 10 MHz. What's more, the new frequency didn't seem to take 10 
>> minutes to
>> settle down. So I tapped on the oven with the screwdriver until it
>> landed right on frequency.
>> The resulting plot is attached.
>>
>> Come to think of it, I could use the counter to measure the time between
>> 1pps and WWVB
>> zero crossing as an ultimate frequency reference as well as detecting
>> changes in the ionosphere.
>
>

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