Block Diagram of Power Supply

unit is removed from the main unit, inter-

inserted in the signal path. In the 20 posi-

t i o n , the -150-volt output of the power

l o c k switch S711 opens and the ac input

supply has a path of continuity to one of

p o w e r path is interrupted from the re-

t h e two relays in the if. step attenuator.

m a i n d e r of the circuitry. The closed con-

W h e n energized, this relay inserts a 10-

dition of interlock switch S711, or the use

d b resistive pad in the if. signal path.

of the alignment harness, permits ac

However, in the 40, 60, and 80 positions

power to flow through vibrating-type reg-

of S701, the -150-volt output of the power

u l a t o r K703 into the primary windings,

supply also has a path of continuity to the

t e r m i n a l s 1 and 2, of power transformer

s e c o n d relay in the if. step attenuator.

T 7 0 2 . One secondary winding, terminals

When both relays in the if. attenuator

1 7 and 18, steps down the 115-volt ac

a s s e m b l y are energized, a total network

input to 6.3-volts ac output, which is used

r e s u l t i n g in 20-db of attenuation is in-

as heater power by all electron tubes

serted in the if. signal path.

except audio amplifier V701 and the stages

h o u s e d in the detector and electrometer

c. Meter Sensitivity Circuit. The 0 CW

a s s e m b l y . A n o t h e r secondary winding,

ONLY position of the SIGNAL ATTENU-

terminals 14 and 16, steps down the 115-

A T O R DB control inserts a 50-ohm re-

v o l t ac input to 5.8-volts ac. This power

s i s t i v e termination in the rf signal path

is used in the heater circuit of audio

for proper impedance matching. While

a m p l i f i e r V701 and detectors V1 and V2

t h i s termination produces a 10-db loss in

i n the electrometer assembly.

r f signal amplitude, wafer switch S701

b. +150 Volt Unregulated Power Circuit.

( f r o n t ) removes a multiplier resistor from

The 115-volt ac power at the primary of

the dc metering signal path. The value of

power transformer T702 is stepped up

t h i s multiplier resistor is equivalent to a

i n voltage through a center-tapped sec-

10-db gain in meter sensitivity; the meter

o n d a r y winding, terminals 3, 4, and 5.

full-scale indication is effectively changed

Parallel-connected rectifiers V704 and

f r o m 10 microvolt to 1 microvolt. There-

V705 produce a dc output of approximately

f o r e , with 10-db of attenuation inserted

+175-volts with respect to chassis ground.

in the rf signal path, the overall result is

This output is filtered and dropped in value

zero attenuation in the combined rf and dc

by the double L-type filter, which consists

m e t e r signal path.

o f reactor L722 and capacitor C734, and

is used as 150-volt B+ power for all stages

13, Block Diagram of Power Supply

e x c e p t the local oscillators in the tuning

(fig. 5)

u n i t s and all tubes in the detector and

T h e power supply provides all of the

electrometer circuit. The dc output of

power requirements for the circuits in

V 7 0 4 - V 7 0 5 is also used as a reference

t h e main unit and in the tuning unit. A

voltage for vibrating-type regulator K703.

simplified representation of the power

T h i s reference voltage is applied to the

s u p p l y is shown in the shunt calibration

coil of the vibrating-type regulator, which

block diagram (fig. 1 and 2). The flow of

a p p l i e s varying amounts of resistance in

power and the development of low-voltage

series with the ac input power, depending

a l t e r n a t i n g current (ac) and rectified dc

on input line fluctuations and output load

v o l t a g e s is shown in the detailed block

variations.

diagram (fig. 5).

c. +105-Volt Regulated Power Circuit.

a. Ac Input and Output Power. Ac input

The 105-volt regulated output is derived

i s connected to the main unit at POWER

from the 150-volt power supply. This 105-

receptacle J721. The voltage is fed through

v o l t output is regulated by voltage reg-

P O W E R switch S710 to interlock switch

ulator tube V708, and is used as B+ volt-

S711 and protective fuse F701. The inter-

age by the local oscillators in each tuning

lock switch is closed when a tuning unit is

unit .

p l u g g e d into the opening provided at the

d. -150- Volt Regulated Power Circuit.

left side of the main unit. When a tuning

Metallic rectifier CR706 is connected to