Radar System Engineering

426 R-F COMPONENTS [SEC. 11.12
when the lid of the whole r-f head is off. The pulse compartment also
contains the magnetron cathode-heating transformer and the necessary
bypass condensers to provide a pulse path to ground in the metering
circuit. All wires that leave this well-shielded compartment go through
.
k,
i
\
j
I
L.
FIG.11.28.—Interior view of a 3-cm airborne r-f head; (a) pulse input; (b) pulse transformer;
(c) pulse compartment; (d) pulse transformer bushing; (e) magnetron cathode
bushing; (f) blower motor; (g) .4FC chassis; (h) receiver chassis; (i) beacon reference
cavity; (j) shield for local oscillators; (k) double mixer; (1) TR tube.
filters which reduce pulse voltages on them to a level that will not interfere
with communications. The pulse transformer case, being the
source of some heat, projects outside the airtight compartment.
The r-f system of this unit is shown in Fig. 11.29. The magnetron,
type 4J52, is of the “packaged” design; the magnet is an integral part of
the tube. It ope~ates at an input level of about 200 kw, with an average
efficiency of about 30 per cent. Its cathode is larger than is usual for