Rectifying and Filtering Circuit.

TM 11-6665-209-40

(3) Rectifying and Filtering Circuit.

HIGH VOLTAGE (900 VOLTS) present in this equipment when operating.

Severe injury or shock can result unless precautions are taken. See

warning pages before servicing.

High voltage for G-M tubes V201 and V202 is furnished from secondary taps 9

and 15 of transformer T101, Tap 15 is grounded. This AC voltage is rectified by

selenium rectifiers CR104 and CR105, which are connected in a half-wave

voltage-doubler circuit. The doubled voltage is built up across capacitor C 1 0 1

The DC voltage pulsations are smoothed and filtered by a filter network con-

sisting of resistors R108 and R110 and capacitors C104 and C105, Approximate-

ly 900 volts DC is present at the input to the filtering circuit.

(4) Regulating Circuit.

The regulating circuit consists of corona voltage-regulator tube V102 and cur-

rent limiting resistor R112. Tube V102 regulates the voltage at +700 volts DC

for application to G-M tubes V201 and V202.

e. Regulated Plate Voltage Power Supply. A secondary winding on transformer T101

provides voltage for the plates of tubes V103 and V104. This voltage is supplied from

taps 10 and 13 of the transformer. Selenium rectifiers CR102 and CR103 provide full-wave

rectification of the square-wave output of the transformer secondary winding. Capacitor

C103 filters the ripple in the rectified voltage. The rectified output is directly connected

to the power supply voltage-regulating circuit, the operation of which has been described

in paragraph 1-10d (2). The plate voltage of tubes V103 and V104 is thus held at a cons-

tant level.

(1) The load upon the plate voltage power supply consists of a series of short-

duration, high-current pulses separated by relatively long periods of zero cur-

rent. The plate supply voltage must remain constant, not only during pulses

but also during interpulse intervals.

(2) Capacitor C103 helps to keep this voltage constant. During each current pulse,

C 1 0 3 acts as a low-impedance source of power. During the interpulse interval,

the charge on C103 is replenished. Capacitor C103 is large enough to prevent

a substantial decrease in plate voltage during the load-current pulse.

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