ground level radiation intensity. It is fed to a cathode follower (V-14) and then transformer coupled to the radio transmitter. 3.2.4 Power Supply Power for the bridge and comparator units is developed in a power supply utilising a Sola constant voltage transformer with B plus VR tube regulation. The converter unit, however, has its own power supply which is floated above ohassis ground, using a standard transformer and VR tube regulation. The instrument is powered 110 volt, 60 cps through a fused plug. 3.4% Meohanical Description me telepulse coding unit consists of four 5" x 7" unit chassis connected together by octal connectors, and mounted on a tray for mechanical rigidity. The overall dimensions are 14-1/8" long by 10-1/," wide, by 7-3/4" high. ‘The assembly fits into a standard aircraft shock mounted rack. 3.4, Junction Box The junction bex contrels the radio communication equipment. A switch on the side of the box allows the operator to use the radio for voice tranamission, voice reception or telemetering transmission. Jacks for connecting a microphone and earphone are provided on the. same side of the box as the switch. The junction box is 9" wide by 7" high by 34" deep and also serves as en interconnecting point for the cables which join the units of the system. 53-5 A circuit diagram is shown in Figure 15. Operation 1. Allow the instrument to warm-up for approximately five minutes. - 34 -