TM 11-5480-281-35/1
which is proportional to regulator Zener current, exceed
g. Protective Circuitry. The transmitter section
+6.8 volts, Zener diode CR270 will conduct, the base of
contains fuses and time-delay relays for circuit
transistor Q204 will be driven positive, transistor Q204
protection.
will conduct, and its collector will go nearly to 0 volt
(1) Three indicating fuses, 01, 01, F202, and
Base current for transistor Q205 can no longer flow
F203, are employed in the transmitter section for ful-
through resistor R238, transistor Q205 will cut off, and
power operation. For half-power operation, dropping
the contact of relay K201 will open.
resistors are inserted in series with the primary power,
f. High-Voltage Power Supply Circuit (Fig.
bypassing the fuses. The high-voltage circuit is protected
by overload circuitry.
7-5). The high-voltage power supply circuit consist of
(2) Relay K206 is a -minute time-delay device
high voltage transformer T201 and a conventional three-
operating on phase C of the ac line, and allows sufficient
phase bridge rectifier E201.
cathode warm up time for magntron V201. Since the
High-voltage transformer T201 (3-phase, wye-
filament power for magntron V201 is derived from the
connected) receives its power from a 120-volt 3- phase,
system +28-volt supply, relay K205 must be operated by
400-Hz source through the closed contacts of relay
28 vdc to sirt the time-day cycle. Relay K206 supplies the
K201. The stepped-up voltage developed across the
solenoid voltage for HV ON relay K201 (fig. 2-).
secondary windings of transformer T201 is rectified by
his ensures preheat for both the magnetron and
bridge rectifier E201 to an unregulated output of
thyratron. Relay K207 is a time-delay holding relay and
approximately +4500 volts. The negative end of the
removes power from relay K206 after the time delay. If
rectifier is returned to ground through bleeder resistors
for any reason the 28-vdc supply is interrupted, relay
R226 and R227 for narrow-pulse operation, and
K207 will restore and the time cycle must be repeated.
through resistor R227, diode CR265, and the closed
contacts of relay K204 for wide-pulse operation. The
difference is necessary because of the difference in
2-3.
Rf Section Description
average current and the requirements for a different
overload sensor tripping current.
a. General. The rf section consists of a ferrite
Figure 2-6. Overload sensor circuit, simplified schematic
2-8
Previous Page
