e-trac depth calibration

  1. E-Trac depth and calibration

    What's the best way to check if an E-Trac is functioning properly? I'm speaking moreso in terms of depth as opposed to ID. Is the best way to bury a coin at x depth or is an air test sufficient? I'm asking because I just aquired an E-Trac and it air tests a quarter at 6" max. Dimes at 4" or 5"...