Extech Instruments 407445, Instruction Manual

Page 4                                                                                                                          Model 407445 Version 2.2 February 2004

Meter Operation 

Getting Started 

1. 

Plug the sensor into the sensor jack at the top of the meter. 

2. 

Press the Power OFF/ON key to turn the instrument on or off. 

3. 

Select the temperature units by pressing the °C/°F key. The display will indicate "°C" 
or "°F" as selected. 

4. 

The meter will now display the per cent relative humidity and the temperature. 

 
NOTE: 

For accurate relative humidity measurements the meter should be allowed 

several minutes to adjust to ambient temperature changes. 
 

Data Hold 

Press the Data Hold key to freeze the displayed temperature and humidity readings. The 
HOLD icon will appear on the display in the Data Hold mode. Press the Data Hold key 
again to exit the Data Hold mode. 
 

MAX, MIN, and AVG Record / Recall 

1.  Press the RECORD key to begin. The REC indicator will appear on the display and the 

meter will begin tracking the highest (MAX), lowest (MIN), and average (AVG) 
readings. 

2.  Press the RECALL key to display the highest (MAX) reading. The MAX indicator along 

with the maximum reading recorded since RECORD was first pressed will appear.  

3.  Press the RECALL key again to view the lowest (MIN) reading.  

4.  Press the RECALL key again to view the average reading (AVG). 

5.  To exit, press the RECORD key. 

Measurement Considerations 

1.  The meter includes an Auto Power OFF feature that turns the instrument off after 

approximately 10 minutes of inactivity. To disable this feature, press the RECORD key 
to enable the MIN/MAX/AVG function. 

2.  It may be necessary to adjust the display contrast due to a change in viewing angle or 

voltage drift. Use the LCD contrast adjustment located on the right side of the meter.