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
