TM 11-6110-211-15
CHAPTER 2
FUNCTIONING
b. Push-Pull Voltage and Power Amplifiers.
2-1. General
Two inputs are applied to the amplifiers through
The purpose, operation, and interoperation of
calibrating resistors R201, R202, and R203. One
the various electrical circuits of the AM-3209/
input is the 400-cycle input voltage from the navi-
ASN are explained in this chapter. Familiarity
gation indicator servo-synchro; the other is a 400-
with the equipment, how it works, and why it
cycle feedback voltage from the navigation indi-
works that way are valuable tools in troubleshoot-
cator motor-generator.
Calibrating resistors
ing the equipment.
R201, R202, R203 match the AM-3209/ASN to
2-2. System Application
the various navigation indicators with which the
AM-3209/ASN maybe used. The input and feed-
a. The AM-3209/ASN amplifies control signals
back voltages, applied from the calibrating re-
from a navigation indicator to drive the naviga-
sistors to transformer T201A, are out of phase and
tion indicator directional mask, heading dial, or
are added algebraically in transformer T201A.
sphere, depending on the navigation indicator
The algebraic sum of the input and feedback volt-
used. The amplified signal output is applied from
ages is applied to push-pull voltage amplifier
the AM-3209/ASN to a motor-generator in the
Q201 and Q202. The output of push-pull voltage
navigation indicator which, through gearing,
amplifier Q201 and Q202 is applied to the in-
drives the navigation indicator mask, dial, or
sphere.
put of push-pull power amplifier Q203 and Q204
The output from push-pull power amplifier Q203
b. The AM-3209/ASN provides a corect-cur-
and Q204 is applied to the control field of the navi-
rent (dc) voltage and two alternating-current
gation indicator motor-generator to drive the
(ac) voltages. The dc voltage may be used to
motor-generator. The direction of rotation for
drive the navigation indicator warning flag. The
the motor-generator is dependent upon the out-
two ac voltages are used as fixed field voltages for
put polarity of the voltage from push-pull power
the navigation indicator motor-generator.
amplifier Q203 and Q204.
2-3. Block Diagram Analysis
2-4. Push-Pull Voltage Amplifier Q201 and
Q202
a. Primary Power. Primary power (115 volts,
400 cycles per second (cps)) is applied from the
aircraft power distribution system to power trans-
Input and feedback voltages (400~) from the
former T202. The output of power transformer
navigation indicator are applied, as appropriate,
T202 drives a full-wave rectifier circuit consisting
through terminals 1, 3, 4, and 5 of P201, and
of diodes CR201 and CR202. The full-wave recti-
through calibrating resistors R201, R202, and
fier power supply provides voltages (22 and 27
R203 to transformer T201A. The feedback volt-
volts) for operation of push-pull voltage ampli-
age prevents excessive rapid rotation of the motor-
fier Q201 and Q202 and push-pull power amplifier
generator rotor. The ground return of the pri-
Q203 and Q204. In addition, the full-wave recti-
mary winding of transformer T201A is completed
fier power supply provides a flag voltage to operate
through pin 6 of connector P201. The voltage
the flag alarm circuit in the associated navigation
developed across the secondary of transformer
indicator. Transformer T202 also applies 26 volts
T201A is applied to the bases of push-pull voltage
ac to the navigation indicator generator fixed
amplifier Q201 and Q202. A center tap on the
field winding and 115 volts ac, through phase-shift
secondary winding of transformer T201A assures
capacitor C204, to the navigation indicator motor
that equal but opposite voltages are applied to
fixed field winding.
Q201 and Q202. Forward bias to the emitters of
2-1
