8. Select FULL SCALE on the calibration box.
9. Then enter the exact value of the standard resistor, using all four digits (eg 300.0) - the
decimal point will be added automatically - and press OK.
10. If the entered value is outside the allowed limits, a long beep will be emitted immediately,
and the user should go back to #9.
11. If the entered value is OK but there is an error in the measurement, a long beep will be
emitted at the end of the measurement. The user should check the settings, and go
back to #8.
12. If the full-scale measurement is successful, a short beep will be emitted, and the user
is returned to #4 with the next range down already selected.
Note:
Calibration mode can be exited by pressing the CAL key at any time, except when a number is
being entered.
Partially-entered codes or values can be cleared at any time by pressing CLE, and then
reentered.
Ideally, the DO7e 600W range should be calibrated against a 600
Ω
standard, but the software
will allow any value between 90
Ω
and 606
Ω
. Similar ratios apply to the other ranges.
CHANGING A PASSCODE
1. Carry out #1 to #4 as above, using the existing passcode.
2. Press and hold the CLE key for 2 seconds - the DO7e displays ‘CODE’.
3. Enter the new 4-digit passcode and press OK - the DO7e displays ‘CODE’ again.
4. Re-enter the new 4-digit passcode and press OK.
5. If the new passcode was not entered correctly both times, a long beep will be emitted,
and the process must be repeated from #3.
6. If correct, the DO7e displays zero (eg ‘0.0’), and is now in Calibration mode. If this is not
required, it can be exited by pressing CAL.
* * END OF NORMAL CALIBRATION PROCEDURE * *
19. USING DISCRETE RESISTANCE STANDARDS
20.1
Discrete, 4-terminal resistance standards may be used in place of the Cropico Calibration
Standard. The standards must have an uncertainty better than 0.01% if the full calibration
accuracy is to be achieved. Full consideration of the DO7e measuring current must also
be taken into account when selecting the standards. The DO7e can be calibrated to
standards between 1000 and 6000 digits for each range using the KYB entry. However,
full accuracy will only be achieved if standards of 4000 to 6000 digits are used. The
following nominal standards are recommended:
400, 40, 4, 400m, 40m and 4m Ohm
Digital Microhmmeter Type DO7e
Operating Instructions
14
