drums with synchronous motors operat-
receiving drum to the transmitting drum
ing at identical speeds. Phasing is ac-
(5) Motor circuit. The motor circuit (V4,
complished by transmitting a series of
V5, and V6) amplifies the 1,800-cycle
transmission. These pulses operate a
signal from the fork oscillator unit and
clutch mechanism which phases the re-
drives the synchronous motor at a con-
stant speed. A multivibrator stage, V26,
ceiving drum to the transmitting drum.
has been incorporated into Facsimile
Transceivers TT-1D/TXC-1, TT-1E/
TXC-1, and TT-1F/TXC-1 to provide
Facsimile Set AN/TXC-1(*).
for half-speed operation of the syn-
a. Electrical Circuits. The complete electrical
chronous motor (par. 71).
(6) B+ regulator circuit. The B+ regulator
circuit of Facsimile Set AN/TXC-1(*), including
Facsimile Transceiver TT-1(*)/TXC-1 and Rec-
circuit (V7, V8, V9, and V25) provides a
tifier Power Unit PP-86(*)/TXC-1, may be
closely regulated voltage of 260 volts
broken down by functions into the following eight
from the rectifier power supply of 450
principal circuits:
volts. Regulated B+ voltage is used on
(1) Signal source at 1,800 cycles. The fork
critical transceiver circuits.
oscillator unit (V1, V2, and V3) generates
(7) Rectifier power supply. The high-voltage
a steady 1,800-cycle audio signal for use
power supply rectifier (V22 in Rectifier
in several other circuits (figs. 30 and 34).
Power Unit PP-86(*)/TXC-1) provides
(2) Photocell bridge modulator. The photo-
unregulated +450 volts. Power trans-
cell bridge modulator circuit (V24), built
former T11 supplies 6.3-volt ac for the
around a type 1645 photocell tube (type
transceiver and power unit tube fila-
ments. Starting voltage for the syn-
5652 in Facsimile Transceivers TT-1D/
T X C - 1 , TT-1E/TXC-1, and TT-1F/
chronous motor and the blower in modi-
TXC-1), is used on transmission only.
fied sets and Facsimile Transceiver
It amplitude modulates the 1,800-cycle
TT-1F/TXC-1, is obtained directly from
signal in accordance with variations in
the ac line. Rectifier Power Unit PP-
light intensity of the small portion of the
86E/TXC-1 also supplies 115-volts ac
for the dust filter blower operation.
transmitted copy being scanned at any
instant.
(8) Exciter lamp supply. The exciter lamp
(3) Signal amplifier circuit. The signal am-
supply (V17, V18, V19, V20, V21, and
plifier circuit (V10, V11, V12, V13, and
V23) in Rectifier Power Unit PP-86(*)/
V14) amplifies the 1,800-cycle am signal
TXC-1 amplifies and regulates the 1,800-
cycle signal voltage from the fork
is used to drive V14 on direct recordings
oscillator unit to provide a steady poten-
only. The other half of V13 is con-
tial for the transceiver exciter lamp,
nected as a meter amplifier for operation
which illuminates the transmitted copy
of the DB METER. On transmission,
with a constant brilliancy.
the photocell bridge modulator feeds the
b. Mechanical System. The mechanical system
signal amplifier circuit, which feeds the
of the facsimile transceiver (figs. 31 and 32) con-
line. On reception, the signal on the line
sists of a synchronous motor which drives the
is fed to the signal amplifier circuit which
rotating drum through a clutch arrangement.
drives either the stylus for direct record-
Operation of the clutch during phasing is described
ing or the recorder lamp for photo
recording. Tubes V10, V11, and V12
also are used in the talk-back circuit.
of the various stages of the facsimile set when
(4) Phasing circuit. The phasing circuit
transmitting. The picture being transmitted is
(V15 and V16) is used only for phasing
attached to the rotating drum, on which the con-
denser lens system focuses light originating at the
the facsimile receiver. A series of phas-
ing pulses from the transmitter actuate
exciter lamp. Varying amounts of light are
a clutch mechanism and phase the
reflected back through the objective lens and
