Originally designed for bomb disposal work the 4020 has numerous other applications.  The unit is supplied with amplifier assembly, piezo (PVDF) contact microphone and headset.   The PROBE INPUT jack accepts transducers and other devices with impedances ranging from 1,000 to over 1,000,000 ohms.

TO OPERATE:  Insert the plug from the transducer element into the PROBE INPUT jack.   Insert the headset plug into the HEADSET jack.   Hold the transducer firmly against the surface being tested and adjust the GAIN as desired.

A single 9 volt battery powers the 4020.   Normal battery life is approximately 100 hours of ON time.  As with any battery operated equipment, remove the battery during periods of prolonged storage.

To replace the battery, loosen the two cover screws one or two turns counterclockwise and, with the lettered side down, carefully remove the back cover. Remove the old battery and replace with a fresh one (Alkaline always preferred).   Replace the cover being careful not to pinch the battery leads and tighten the screws (do not over-tighten).