This would indicate the output voltage that has been generated by the unit and applied to the target utility. The High Voltage LED will appear if the unit detects the presence of high voltage, use “high voltage precautions” to carefully disconnect the line transmitter from the high voltage source.
RIDGID ST510 Transmitter is a portable, easy to use line transmitter. It delivers the power and performance you expect for any high-class transmitter available on the market.