Sync Pulse Output - HP 202A Operating And Service Manual

Sect.
1 1 1
Page 7
R 4 4 R41
C Z O
Figure 3-8. Sync Output Circuit of Model 202A
attenuated before being applied to the cathode follower
grids. The small shunt capacitors on the upper sides
of the dividers improve the high frequency response
of the amplifier. The voltages appearing a t the
cathode follower output terminals are equal in mag-
nitude and 180" out of phase. Negative feedback is
used to reduce distortion, lower the output impedance
and improve stability. This improved stability
applies not only to the signal output, but to the dc
level a t the output terminals.
The symbol for chassis o r ground is used for the
first time in the output terminal network R98, R99
and C29. In all other description the reference level
for operation has been B-, and in the Model 202A
the B- line is completely isolated from the chassis.
Thus, the chassis ground is available for whatever
connection
is
desired. It is possible to consider
the two output terminals a s a transformer output
and further to balance this apparent transformer to
chassis by making R98 equal to R99. The capacitor
C29 insulates the apparent transformer secondary
from ground.
If
single-ended operation is desired
the ground connection can be tied to either output
terminal without affecting the amplifier.
3-6 SYNC PULSE OUTPUT
The output sync pulse is obtained from the bi-stable
circuit V1 and V2. On the minus switching reference
a t the plate of multiar diode V3, one positive pulse
and one negative pulse appear for every cycle of
operation. These pulses a r e coupled to the grid
REGULATOR
F l E R
f
375 VOLTS REG
. - 0
+P25
VOLTS REG
-
r s
REG
Figure 3-9. Model 202A Power Supply