ARMING SAFETY SWITCH MK 122 MOD 0

ARMING SAFETY SWITCH MK 122 MOD 0 The Mk 122 Mod 0 arming safety switch (fig. 1-14) connects the fuze control circuits of the bomb in the aircraft to the electric fuze circuits in the bomb. This switch provides an open circuit and a RADHAZ shield to prevent electromagnetic radiation from entering the fuze circuits. While the weapon is loaded, the coaxial cable of the switch is plugged into the receptacle of the aircraft’s electrical arming unit. When the bomb is suspended from the rack, the lanyard is attached to a fixture on the rack or pylon. Upon bomb release, the lanyard pulls the lanyard pin and closes the fuze circuit. The lanyard is long enough so the weapon separates from the bomb rack suspension hooks before the lanyard pin is pulled from the switch. This ensures that the fuze does not receive charging voltages in case of weapon release failure. The coaxial cable is longer than the lanyard, which permits sufficient time for the charging voltage to pass from the electrical arming unit on the aircraft to the fuze electric circuits on the bomb before the cable is pulled free or breaks from the arming unit receptacle. NOTE: The Mk 122 Mod 0 switch must be installed and removed in a RADHAZ-free environment. MK 43 MOD 0 TARGET DETECTING DEVICE The Mk 43 Mod 0 target detecting device (fig. 1-15) is a proximity variable time (VT) nose element that gives airburst capability for electric-fuzed Mk 80 (series) bombs. The Mk 43 Mod 0 VT element is compatible with all electric tail fuzes and is identified by the dark green color of the nose cone. Its internal circuitry is powered by a thermal battery. The thermal battery is initiated by +300 volts dc or by the striker rod. The Mk 43 is initiated mechanically (striker rod) only when a delay airburst is desired. This is the alternate method used to provide VT operation when the fuze is not initiated with the +300 volts dc. The conventional VT mode is selected by initiating the fuze with +300 volts dc. When the fuse is initiated with +300 volts dc, the Mk 43 operates automatically. Figure 1-14.—Mk 122 Mod 0 arming safety switch. 1-20