Power Supply, Analysis of Input Circuits

high-voltage secondary winding of trans-

i n s e r t e d within the main unit. (Interlock

f o r m e r T702 (terminals 6 and 7) is con-

s w i t c h S711 breaks the ac input circuit

n e c t e d to metallic rectifier CR705. The

when a tuning unit is withdrawn from the

output of this rectifier is regulated at 300-

m a i n unit.) Receptacle J722, located on

volts by two series-connected voltage reg-

the main unit compartment for the tuning

ulators V706 and V707. This output is used

u n i t (fig. 46), is provided as a means of

as either positive or negative, with respect

bypassing interlock switch S711 when

t o chassis ground, by POLARITY switch

operation of a tuning outside of the main

S 7 0 9 . The output of this 300-volt supply

u n i t is required. For example, this type

i s connected in series with an additional

o f operation is necessary when aligning

positive or negative supply to produce from

( o r taking voltage and resistance meas-

300- to 450-volts output of either polarity.

urements on) a tuning unit. The two-prong

Polarity switching is provided so that the

c o n n e c t o r , P901, is part of the alignment

pulsed output of the impulse generator can

h a r n e s s . With this connector inserted in

be either positive or negative with respect

r e c e p t a c l e J722 (and with the two inter-

t o chassis ground, depending on test cir-

l o c k switches on the alignment harness

cuit conditions.

closed), the terminal B leg of the ac input

line has a path of continuity through filter

14. Power Supply, Analysis of Input

F L 7 0 4 to the common side of voltage-

Circuits

dropping resistors R764 to R769 and R771

to R774. The ac input circuit to terminal

(fig. 6)

2 of transformer T702 is completed by the

T h e power supply provides all of the

p a t h of continuity created when one or

power requirements for the circuits in the

more of the shunt resistors (R764 to R769

main unit and in the tuning unit. The input

and R771 to R774) or the shorting link at

v o l t a g e is controlled by a vibrating-type

t e r m i n a l 5 of relay K703 makes contact

regulator. Three of the dc output voltages

w i t h the relay armature. Filters FL703,

a r e controlled by voltage regulator tubes.

F L 7 0 4 , and FL705 and capacitor C727

P a r a g r a p h 13 presents a block diagram

prevent interference of relay c o n t a c t

d e s c r i p t i o n of the power supply (fig. 5).

a r c i n g from affecting the sensitive cir-

The following subparagraphs describe cir-

cuits of the test set.

cuit functioning with reference to the sim-

b. V i b r a t i n g- T y p e Regulator K703.

plified schematic diagram (fig. 6).

Vibrating-type regulator K703 is made up

a. Ac Input Circuit. Ac power at 115-

o f three basic elements: a current-sensi-

volts, 50- to 400-cps, is connected to the

tive signal coil (terminals 13 and 14), a set

m a i n unit at three-terminal POWER re-

of contact fingers (terminals 1 through 11),

ceptacle J721. Terminals A and B of J721

a n d a pivoted contact bar. The magnetic

receive power from the two input legs of

circuit of the signal coil is closed through

t h e ac powerline. Terminal C serves as a

a moving armature. As the armature

g r o u n d i n g pin to prevent electrical shock

m o v e s , a lever arm pushes the contact

to operating personnel. Terminal A of J721

f i n g e r s off a common contact bar one at

i s connected by one section of filter FL-

a time. The contact fingers are elec-

7 0 3 , the OFF position of POWER switch

trically connected to terminals at the base

S710, fuse F701, the primary winding

o f the vibrating type regulator. As the

( t e r m i n a l s 1 and 2) of transformer T702,

fingers close, externally mounted re-

a n d filter FL705 to the armature on vi-

sistors R764 through R769 and R771

b r a t i n g - t y p e regulator K703. Terminal B

through R774 are connected, one at a

o f J721 is connected through the second

t i m e , to the control circuit. The pivoted

s e c t i o n of filter FL703 and the ON posi-

c o n t a c t arm is attached to the lever arm

t i o n of POWER switch S710 to interlock

through a coupling spring.

switch S711. This interlock provides a path

c. Regulating Circuit. T w o m a j o r

of continuity for terminal B leg of the ac

f o r c e s act on the armature: The magnetic

input powerline when a tuning unit is fully