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 C2, TM 11-6625-564-45
1-14. Transient Blanker
relay K2 when relay K2 is energized. The
+27.5 volts dc is applied to the emitter of tran-
(fig 4-8 , 4-8.1)
sistor Q2 and through resistor R1 to the emit-
ter of transistor Q1. When a positive tran-
a. Function. In
MK-731/ARC-51 X
only,
sient pulse appears with the +27.5 volts dc,
the transient blanker circuit protects the
transistor Q2 conducts more, and thereby in-
transistorized stages within power convert-
creases the voltage drop on resistor R3. The
er module 1A3 and audio amplifier modules
positive base bias of transistor Q1 increases.
1A1 and 1A2, and uhf test generator module
The effects of the positive transient pulse and
1A5.
In this module, transient pulses are
the increased positive base bias on transistor
eliminated from the +27.5-volt dc supply. It
Q1 counteract and maintain a constant +27.5
also drops the +27.5 volts dc to +18.9 volts
volts dc. This transient protected +27.5 volts
dc for the filament circuit of uhf test gener-
dc is applied to the collector of transistor Q3
ator module 1A5 and +20.0 volts dc for the
and to the voltage divider network of R5 and
B+ circuit of audio amplifiers 1A1 and 1A2.
CR2. The voltage at the junction of CR2 and
a.1. Function. In MK-731A/ARC-51X, the
transient blanker circuit protects the tran-
R5 is held at a constant +20 volts dc be-
sistorized stages w i t h i n p o w e r c o n v e r t e r
cause of Zener diode action. The +20-volt dc
output of cathode follower Q3 is used as a B+
module 1A3, audio amplifier modules 1A1
and 1A2, and uhf test generator module 1A5.
supply for audio amplifier modules 1A1 and
In this module, transient pulses are elimi-
1A2. This +20 volts dc is also applied to re-
nated from the +27.5-volt dc supply. It also
sistor RC, which reduces the potential to
drops the +27.5 volts dc to +20.0 volts dc for
+ 18.9 volts dc, and this voltage is supplied to
the B+ circuit of audio amplifiers 1A1 and
uhf test generator module 1A5 at terminal El
1A2.
where it serves as a filament voltage supply.
b. Analysis. The + 27.5 volts dc is applied
Filament voltage is not required for the
to transient blanker input terminal E1 through
MK-731A/ARC-51X.
8.1/(8.2 blank)
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