User’s Manual Model 407744 and 407766 Sound Level Calibrators
Introduction Congratulations on your purchase of Extech’s Sound Level Calibrator. Extech Calibrators accommodate Sound Level Meters with 0.5” and 1” microphones. The Calibrator’s die-cast aluminum housing is built for ruggedness and durability. The 407744 provides a 94dB calibration output signal while the 407766 provides both 94dB and 114dB outputs. This professional calibrator, with proper care, will provide years of safe reliable service.
Description Note that only the 407766 is pictured. 1. ½” Microphone adaptor * 2. 407766: OFF-94dB-114dB switch 407744: OFF-BATTERY TEST-94dB switch 3. 407766: POWER-ON / LOW-BATTERY status LED 407744: BATTERY OK LED 4. Battery compartment cap * To remove the ½” adaptor, pull straight down as shown in diagram below. 3 407744 & 407766 - V5.
Operation Theory of Operation The 407744 sound level calibrator generates a 94dB sine wave at 1 KHz. The 407766 generates a 94dB and a 114dB sine wave at 1kHz. When a microphone from a sound level meter is inserted into the calibrator, the sound level meter picks up the signal and displays the signal in dB (decibel) units. The sound level meter should be adjusted (if necessary) to match the calibrator’s output signal as closely as possible (see diagram). Procedure 1.
Warranty EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects in parts and workmanship for one year from date of shipment (a six month limited warranty applies to sensors and cables). If it should become necessary to return the instrument for service during or beyond the warranty period, contact the Customer Service Department at (781) 890-7440 ext. 210 for authorization or visit our website www.extech.com for contact information.
