WWII Command Set radio checkout in a P-47 Thunderbolt

PREFLIGHT RADIO INSPECTION FOR FIGHTER AIRCRAFT is a WWII film made for newbie Army Air Force Radio Mechanics. The film shows a P-47 Thunderbolt's SCR274 radio being checked out on the ground, part of the routine pre-flight for any fighter aircraft. What's really interesting about it, is that the film really goes into great detail on the inspection including showing the various forms that would be filled in during a check, and the entire process by which planes were approved for flight by radiomen. The various steps of check out are shown, with examination of the receivers, transmitters, headsets, and even making sure that the instruction book is in place.    The film shows a complete inspection and operational checkout of the SCR274 "Command Set" radio including all LF and HF radios, antenna, and modulator.

At the 10 minute mark the film switches from focusing on the SCR274 to an aircraft equipped with an SCR-522, which can provide two-way radio-telephone communication between aircraft in flight and between aircraft and ground stations. At the 13:00 mark, a P-38 Lightning is checked out. This aircraft has a SCR-522 on board, with the radio set behind the pilot. An early model P-51 is shown with an SCR274 at the 13:20 mark. Operation of the SCR-522 may take place on any one of four crystal-controlled channels lying within the frequency range of 100 to 156 megacycles. Remote control only is provided. Radio set SCR-522 operates from a 28-volt source and uses dynamotor PE-94-A ; radio set SCR-542 operates from a 14-volt source and uses dynamotor PE-98- A. Radio sets SCR-522 and SCR-542 differ only in the primary power supply voltage and the dynamotor unit used.

If you've never seen how these famous radios were actually installed, this is a must-see!  And make sure a copy of the instruction manual is onboard, just in case...