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P R I N C I P L E S O F O P E R A T I O N
tor circuit i s a p p l i e d ) V105 is on (conducting) and
4.4.7 TRIGGER AMPLIFIERS.
about 6OmA flows through the output resistors.
Start-Signal Action
4.4.5 -OUTPUT AMPLIFIER.
Quiescent:
V106
OFF
4103 and 4104 are the trigger amplifiers. Both
are biased off. Since both are npn transistors, a posi-
The negative output pulse
starts
from
volts and
tive pulse applied t o their b a s e s will turn them on for
falls t o - 6 o v o l t s , Therefore, in the quiescent s t a t e ,
the duration of the p u l s e . When a start s i g n a l (positive
VlO6 is
off
(not conducting), no current flows through,
p u l s e )
arrives from
the
and prf circuit, it is
its plate load resistors and the -OUTPUT point r e s t s
applied t o the b a s e of 4103. 4 1 0 3 conducts and pro-
a t ground potential
(
0 volts
).
duces a negative pulse a t i t s collector.
4.4.6 MULTIVIBRATOR DRIVER,
OUTPUT AMPLIFIER BIAS.
Quiescent:
QlOl
OFF,
Q102
ON
The plate voltages of the output amplifiers are
controlled by their grid voltages, which, in turn, are
controlled by the bistable driver, which c o n s i s t s of two
npn transistors, QlOl and 4102.
As noted before, V105 is on in the quiescent state,
which means i t s grid b i a s must be low enough t o allow
conduction. V105 and
~ 1 0 6
are self-biased by their
common cathode resistor R156, through which about
70 milliamperes flow
for a 2-volt bias. If QlOl were
on (conducting), current would flow through R154, and
the voltage drop across R154 and R156 (V105 b i a s )
would be sufficiently large to turn off V105. SinceVlOS
i s on, QlOl must be off. When QlOl is off, 4102 i s on
b e c a u s e the two transistors .form a bistable multivibrator.
With 4 1 0 2 on, current flows through R157 t o b i a s VlO6
off
-
the quiescent condition described above in para-
graph 4.4.5.
1
STOP
I
STAR 1
4.4.8 MULTIVIBRATOR DRIVER SWITCHING.
Start-Signal Action
SWEEP GENERATOR
"
3
AND CLAMP
The negative p u l s e a t the collector of 4 1 0 3 is
coupled t o the b a s e of 4102 and c a u s e s 4 1 0 2 t o start
t o turn off. 4 1 0 2 is one half of a multivibrator that con-
s i s t s of 4 1 0 2 and 4101; a s 4 1 0 2 s t a r t s t o turn off,
4 1 0 1 s t a r t s t o turn on. T h i s is the normal regenerative
action of any multivibrator and the discussion that
follows describes the switching action and the regen-
erative paths of QlOl and 4102.
T h e negative pulse a t the b a s e of 4102 appears
a s a positive pulse a t the collector of 4102. T h i s pos-
itive pulse is coupled through C134to the b a s e of QlOl
and c a u s e s QlOl t o start t o turn on. T h e positive pulse
a t the b a s e of QlOl appears a s a negative pulse a t the
collector. T h i s negative pulse is coupled through C133
and R139 back t o the b a s e of 4102, a i d s the negative
pulse already present from the collector of 4103, and
thus completes the regenerative loop. Upon completion
of the switching action, QlOl is on and 4 1 0 2 i s off.
F i g u r e
4-5.
S i m p l i f i e d schematic
diagram of the output-pulse c i r c u i t .
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