ECOTEST DKG-21 Operating Manual page 45

Set an appropriate value of the low-order digit by successively pressing
and releasing the THRESHOLD button. Press shortly the MODE button to
proceed to programming of another digit, the latter will start blinking. Set
the required value of the digit by pressing and releasing the THRESHOLD
button.
After the last digit of the threshold level is set and at next pressing of
the MODE button, the dLCD will blink four times, indicating that the new
value has been memorized, and the dosimeter will return to the mode of
DE indication.
The threshold level is stored in the nonvolatile memory of the
dosimeter. Switching the dosimeter on and off and replacing its battery
does not change the threshold level.
Press the THRESHOLD button and hold it down for maximum 4 s after
a threshold level value and the ALARM transparency appear to check the
value of the DE threshold level.
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