Production 1947(I think).
The Hammarlund Four 20 is a CW transmitter and is crystal controlled from 80 through 10 meters. This transmitter uses a single 807 tube as the final. The power source is 115 volts AC. This transmitter is often paired up with the Hammarlund HQ-129X receiver. This transmitter will soon find its way to the work bench for a total restoration.