Calibration equipment for calibrating multiple test stations in a test system is provided. Each test station may include a test unit, a test chamber with an over-the-air antenna, and a radio-frequency (RF) cable that connects the test unit to the test chamber. Reference devices under test (DUTs) may be used to calibrate uplink and downlink path loss (e.g., OTA path loss, RF cable path loss, and variations of the test unit) associated with each test station. The reference DUTs may calibrate each test station at desired frequencies to generate a path loss table. Once calibrated, the test chambers may be used during production testing to test factory DUTs. During production testing, the transmit/receive power efficiency of each factory DUT may be calculated based on values in the path loss table to determine whether a particular production DUT is a passing or failing DUT according to pass/fail criteria.