TM 11-6110-211-15
push-pull voltage amplifier Q201 and Q202 is pro-
through pins 13 and 14 of connector P201 to the
vided by the voltage developed across mister R204
motor control field of the motor-generator in the
and the parallel arrangement of resistor R212 and
navigation indicator. The dc ground return for
thermistor RT201 (a negative temperature coeffi-
transistors Q203 and Q204 is through the control
cient resistor which keeps the bias constant under
field of the navigation indicator motor-generator
varying temperature conditions). Resistors R209
via terminals 13 and 14 of P201. Capacitor C203
and R204 and the parallel arrangement of resistor
is connected in parallel with the collectors and the
R212 and thermistor RT201 form a voltage di-
output (control field of the motor) to present a
vider network across power supply output filter
nonreactive load to the push-pull power amplifier.
capacitor C205.
The voltage divider network
Fuses F201 and F202 provide overload protection
provides the base-emitter bias voltage for Q201
for transistors Q203 and Q204.
and Q202. Resistors R205 and R206, in the emit-
2-6. Power Supply
ter circuits, provide for dc bias and stability and
prevent transistor thermal runaway. The output
Ac power (115-volt, 400-cps) from the aircraft
of push-pull voltage amplifier Q201 and Q202 is
power supply is applied to the input section of
applied through coupling transformer T201B to
power transformer T202 through pins 7 and 12 of
push-pull power amplifier Q203 and Q204. The
connector P201. The ac voltage is also fed from
primary of transformer T201B is tuned to 400
pin 7 of connector P201 through phase-shifting
cycles by capacitor C202 in series with resistor
capacitor C204 and pin 11 of connector P201 to the
R213.
fixed field of the navigation indicator motor-
2-5. Push-Pull Power Amplifier Q203 and
generator. A tap on power transformer T202 sup-
Q204
plies 26 volts ac, 400 cps, at 0 reference phase
through pin 8 of connector P201 to energize the
The output of coupling transformer T201B is
fixed field of the navigation indicator motor-
applied to the bases of transistors Q203 and Q204,
generator. Full-wave rectification is accomplished
which form a push-pull power amplifier circuit.
by diodes CR201 and CR202. Resistor R210 and
A center tap on the secondary winding of trans-
capacitor C205 filter the output of the full-wave
former T201B assures equal and opposite voltages
rectifier. Unfiltered 27 volts dc from the junction
and provides forward bias to the emitters of tran-
of CR201 and R210 is applied as operating voltage
sistors Q203 and Q204. Operating bias for tran-
for the push-pull power amplifier. The unfiltered
sistor Q203 is applied through resistor R207 and
27 volts dc is also applied through dropping re-
fuse F201. Operating bias for transistor Q204 is
sistor R211 and pin 10 of connector P201 as flag
applied through resistor R208 and fuse F202. Re-
current to control a warning flag in the navigation
sistors R207 and R208 and fuses F201 and F202
indicator. Filtered 22 volts dc from the junction
are in parallel with bypass capacitor C206. The
of R210 and C205 is applied as operating and bias
output of push-pull power amplifier Q203 and
Q204 is taken from the collectors and is applied
voltage for the push-pull voltage amplifier.
2-3
