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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