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5.5.1 Humidity Calibration

To enter the humidity calibration mode, press and hold the SET/ADJUST and CLEAR/- buttons at

the same time for 5 seconds and the humidity value will begin flashing. Press the [+] button to

increase the humidity and the CLEAR/- button to decrease the humidity reading in 1% increments. To

rapidly increase (or decrease) the humidity reading, press and hold the [+] or CLEAR/- button.

To return the humidity to the actual or uncalibrated measurement, press the ADJUST button.

Once the displayed humidity equals the calibrated source, press and hold the ADJUST button for

three seconds, or wait 15 seconds for timeout, and the humidity value will stop flashing.

Discussion: Humidity is a difficult parameter to measure electronically and drifts over time due to

contamination.

Due to manufacturing tolerances, the humidity is accurate to ± 5%. To improve this accuracy, the

humidity can be calibrated using an accurate source, such as a sling psychrometer:

http://www.ambientweather.com/mafaredspslp.html

or one step humidpak calibration kits (reference Section 9). You can also use common table salt,

water and a plastic bag:

https://ambientweather.net/help/how-can-i-test-the-accuracy-of-my-hygrometer/

5.5.2 Temperature Calibration

To enter the temperature calibration mode, press and hold the SET/ADJUST and [+] buttons at the

same time for 5 seconds and the temperature value will begin flashing. Press the [+] button to increase

the temperature and the CLEAR/- button to decrease the temperature reading in 0.1° increments. To

rapidly increase (or decrease) the temperature reading, press and hold the [+] or CLEAR/- button.

To return the temperature to the actual or uncalibrated measurement, press the ADJUST button.

Once the displayed temperature equals the calibrated source, press and hold the ADJUST button for

three seconds, or wait 15 seconds for timeout, and the temperature value will stop flashing.

Discussion: Temperature errors can occur when a sensor is placed too close to a heat source (such

as a computer or TV or in a window).

To calibrate temperature, we recommend a mercury or red spirit (fluid) thermometer. Bi-metal (dial)

and other digital thermometers are not a good source and have their own margin of error.

Ambient Weather WS-26 User Manual

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