Details: Two tetrode vacuum tubes that amplified the frequency shift keyed signal to about 200KW that was applied to the Short Trailing Wire Antenna. Working with the neutral Long Wire Antenna as a reflector to magnify the radio signal at VLF frequencies that are carried around the world. The “Ironman” was the container around tetrode tubes that had distilled/deionized water circulated through a heat exchanger to remove the heat created by the tubes.