1.2- Volt Dc Power Circuit for Electrometer V4

m a i n unit receptacle J701 to the mating

of main unit receptacle J701. These ter-

plug on the tuning unit.

m i n a l s supply heater power for electrom-

One

h. +300- Volt Dc Power Circuit.

e t e r V3, in the detector and electrometer

s e c o n d a r y winding (terminals 6 and 7)

assembly of the tuning unit. Resistor R775

steps up the input voltage to 500-volts. The

i s a voltage-dropping resistor.

voltage is r e c t i f i e d by a half-wave

e. 1.2- Volt Dc Power Circuit for Elec-

m e t a l l i c - t y p e rectifier CR705. The recti-

trometer V4. One secondary winding (ter-

f i e r output is filtered by a pi-type net-

minals 8, 9, and 10) of T702 performs the

work which consists of resistor R779 and

same function as that described in d above.

the two sections of a dual capacitor C733.

Crystal rectifiers CR703 and CR704, con-

Resistor R781 is the voltage-dropping re-

n e c t e d in a full-wave circuit, rectify the

sistor for the series -connected regulators

s e c o n d a r y voltage. The output is filtered

V706 and V707, which holds the output at

by a pi-section filter that consists of

3 0 0 - v o l t s . Resistor R782 is a voltage-

variable resistor R778 and capacitors

d r o p p i n g resistor. The output can be re-

C731 and C732. Resistor R778 is used to

v e r s e d in polarity by setting POLARITY

adjust the dc output to 1.2 -volts, which is

s w i t c h S709 to either its plus or minus

c o n n e c t e d to contacts 9 and 11 of main

p o s i t i o n . T h e terminals of this double-

unit receptacle J701. These terminals

p o l e double-throw (dpdt) switch are tied

s u p p l y heater power for electrometer V4,

to both the negative 150-volt output (from

i n the detector and electrometer assembly

V 7 0 9 ) and the positive 150-volt output

o f the tuning unit. Resistor R777 is a

( f r o m V704-V705) for reference. Circuit

v o l t a g e - d r o p p i n g resistor.

operation is as follows:

(1) The high side of variable resistor

f. 5.8- Volt Ac Power Circuit. One sec-

R 7 6 2 B is connected to the +150-

o n d a r y winding (terminals 14 and 16) of

volt output of rectifiers V704 and

T 7 0 2 provides heater current for audio

V 7 0 5 . The low side of R762B is

a m p l i f i e r V701 and for the two detector

connected to chassis ground. When

stages housed `in the tuning unit. Potenti-

POLARITY switch S709 is set to its

ometer R706 is connected across the 5.8-

+ position, the variable arm of

v o l t ac input to the heater terminals of

R762B has a path of continuity to

V701, pins 5 and 9. The arm of R706 oper-

t h e negative 300-volt output from

ates at chassis ground potential. The 5.8-

the cathode of regulator V707. This

v o l t ac input voltage across V701 heater

c i r c u i t arrangement can produce a

i s divided in half by setting the arm of

total usable output which is the sum

potentiometer R706 at the midpoint of its

o f +150-volts to chassis ground,

range. This setting of R706 tends to cancel

a n d the potential difference from

o u t any hum that may be picked up and

c h a s s i s ground to -300-volts. The

a m p l i f i e d by audio amplifier V701. The

t o t a l potential which can be ob-

f u l l 5.8-volts ac is available at terminals

tained across this network is 450-

5 and 6 of main unit receptacle J701. The

v o l t s . A variation of 150-volts is

m a t i n g plug at the rear of a tuning unit

o b t a i n e d by rotating the arm of

a p p l i e s this 5.8-volt ac heater power to

IMPULSE GEN LEVEL SET con-

the two detector stages within the detector

trol R762. The setting of the poten-

a n d electrometer assembly.

t i o m e t e r determines the charging

voltage, applied through the 10-db

g. 6.3-Volt Ac Power Circuit. O n e

step coarse attenuator control S708

center-tapped secondary winding of trans-

to impulse generator G701. During

f o r m e r T702 (terminals 17 and 18) pro-

c a l i b r a t i o n of the equipment, the

vides heater current for all tubes and pilot

variable arm of R762 is set so that

l a m p s in the equipment, except for those

the output amplitude from impulse

tubes housed within the detector and elec-

generator G701 is equivalent to the

trometer assembly. Heat e r power is

o u t p u t from an external impulse

c o u p l e d through termimls 16 and 17 of