[time-nuts] J06 HP-59992A time interval calibrator for HP-531xx counters

Orin Eman orin.eman at gmail.com
Sun Jul 9 20:21:10 UTC 2017


On Sun, Jul 9, 2017 at 10:55 AM, jimlux <jimlux at earthlink.net> wrote:

> On 7/9/17 10:27 AM, Bob kb8tq wrote:
>
>> Hi
>>
>> People *have* been known to sort MiniCircuits parts and use the “extras”
>> in
>> something else. A certain major oscillator manufacturer once bought a
>> bunch
>> of RPD-1’s , sorted them for the “one in a hundred” examples, and then
>> returned
>> the rest for credit…… Somehow I doubt HP didi it quite that way.
>>
>>
> Some manufacturers will cherry pick for you.  Maybe the datasheet says
> gain is 14 to 18 dB, and you order a batch that you want to be 15.5-16.5
> dB.. They'll pick those out, but of course, now the remainder have a hole
> in the distribution.  Particularly when you're buying high-rel or space
> grade, where they have to 100% test anyway.



Right, but there is nothing to indicate there is anything special going on
in this case.  The theory of operation section of the manual states that
the splitters provide "nearly" in-phase and "nearly" out-of-phase signals
without defining "nearly".  It does not sound like it's critical and to me,
it sounds like they are acknowledging that there are phase mismatches
through the splitters.

Then going on to the other link I posted:

http://www.g8wrb.org/data///HP/Better_than_100_ps_Accuracy_in_HP_5370B_Time_Interval_Measurements_Through_Bias_Error_Reduction.pdf

It accounts for the individual delays through the splitters/cables and
shows how they are eliminated by doing multiple measurements and solving
the resulting simultaneous equations.

Indeed, the programs in the J06's manual mention that 'cable' mismatches
(presumable phase mismatches) are included in the calibration constants and
the same cables should be used for doing actual measurements: (the
formatting did not survive and I fixed some obvious OCR errors)

40 ! THIS PROGRAM EXECUTES THE CALIBRATION ALGORITHM DESCRIBED IN D. CHU'S
50 ! PAPER "CALIBRATION OF SYSTEMATIC ERRORS IN PRECISION TIME-INTERVAL
60 ! COUNTERS", INTERNATIONAL TEST CONFERENCE, PHILADELPHIA, 1985;
70 !
80 ! SET-UP PROCEDURE
90 ! 1) CONNECT A PULSE SOURCE TO THE INPUT OF CALIBRATOR, 3 DB LARGER
100 ! THAN THE DESIRED SIGNAL TO BE MEASURED AND APPROXIMATELY THE
110 ! THE SAME RISE/FALL TIMES, -50% DUTY-CYCLE, STABLE 1 TO 100 MHz.
120 ! 2) CONNECT A PAIR OF CABLES FROM CALIBRATOR OUTPUTS A & B
130 !  TO COUNTER START & STOP INPUTS RESPECTIVELY
140 ! (NOTE: CABLE MISMATCHES ARE INCLUDED IN THE CALIBRATION CONSTANTS,
150 ! AND SAME CABLES SHOULD BE USED LATER FOR DOING MEASUREMENTS;
160 ! ALSO "CABLES" INCLUDE LINEAR, PASSIVE OR ACTIVE PROBES)
170 ! 3) SET COUNTER TO SEPERATE: DC/50 ohms/Xl/PRESET to BOTH CHANNELS
180 ! 4) HPIB ADDRESSES: COUNTER-707, CALIBRATOR-705
190 ! 5) CONNECT A PRECISE OFFSET VOLTAGE SOURCE TO THE OFFSET INPUT: ENTER
200 ! THE EXACT SAME VALUE WHEN PROMPTED. DEFAULT IS 0.00 VOLT



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