Power Supply - GENERAL RADIO COMPANY 1398-A Operating Instructions Manual

PRINCIPLES OF O P E R A T I O N
4.4.13 STOP-TRIGGER AMPLIFIER.
Stop-Signal Action
The stop-trigger amplifier behaves in the same
fashion a s the start trigger amplifier when it receives
a positive pulse, i.e., it reverses the s t a t e of the multi-
vibrator, which, in turn, reverses the s t a t e of the output
amplifiers. Thus VlO5 i s turned back on,VlO6 i s turned
off, a l l circuits have returned t o their quiescent levels,
and the output pulse i s terminated.
4.5 POWER
SUPPLY.
(
Figure 4-6).
4.5.1 GENERAL.
Both the positive and negative 150-volt supplies
are highly regulated with conventionalamplifier, s e r i e s -
tube, voltage regulators. The negative supply contains
the reference tube and i s therefore the primary regulated
voltage source. T h e positive supply obtains i t s refer-
ence from the negative. The raw d c s,ource for e a c h
supply i s a full-wave bridge rectifier with a capacitor
input filter. CR501, CR502, CR503, and CR504 provide
+
225 volts with respect to ground to the first half of
V501, the positive s e r i e s tube. In similar fashion
CR505, CR506, CR507, and CR508 provide a n equal d c
and R513 form a voltage divider establishing the grid
potential of amplifier tubeV503 at a level very slightly
more negative than the cathode. T h e plate current of
V503 in R507 controls the drop a c r o s s V501. V501 and
V503 are therefore an amplifier with high gain and any
attempt by V503's grid voltage t o change with respect
t o i t s cathodevoltage results in a compensating change
in the voltage drop a c r o s s V501. T h e drop a c r o s s R.513
and t o the t o p of R512 is therefore held very constant
and i s near 8 0 volts.
4.5.3 THE POSITIVE VOLTAGE SUPPLY.
The constant -150-volt source established with
V501J3, V503, and V504 is used a s a reference for the
positive supply. The plate current of V502, the cathode
of which i s grounded, in R501 controls the drop a c r o s s
V501A. Thus V501A and V502 comprise a n amplifier
with high gain. The grid voltage of v502,only slightly
negative (one volt) with respect t o i t s cathode, i s e s -
tablished by the voltage divider consisting of R504,
R505, and R506. T h i s divider is s e t s o that the portion
of resistance above the t a p i s equal t o that below. For
the grid voltage of V501 t o be near zero volts the out-
put voltage a t pin 3 of V501 must be 150 volts.
voltage which divides a c r o s s the second section of
V5Ol and the load t o ~ r o v i d e -150 volts regulatedwith
4.5.4 THE HEATER VOLTAGE SUPPLY.
-
respect to ground.
Two heater b u s s e s are used in the Type
1398-A.
4.5.2 THE NEGATIVE VOLTAGE SUPPLY.
The 6.3-volt d c heaters of V101, V102, V104, V501,
and V502 are fed from a common b u s s a t ground poten-
R510 and V503 draw about 10 milliamperes of
tial. The heater supply for V103,V105,V106, and V501
current in V504, the voltage reference tube. T h e drop
is biased t o
-
70 volts dc by a divider from
-
150 volts
across V504 i s a very constant 80 volts. R511, R512,
comprised of R514, R515, and R518.