value of numerous individual components has
(1) The purpose of this modification is to
changed slightly in Facsimile Sets AN/TXC-1A,
provide an external loudspeaker for
-1B, -1C, and -1D to conform with American
War Standards values. In most cases, the differ-
Facsimile Transceiver AN/TXC-1A.
(2) The talk-back circuit is the part modified.
ences are less than the plus or minus 10 percent
b. MWO SIG 11-2258-1.
tolerances of the components, and are of no
(1) The purpose of this modification is to
significance.
make audible to the receiving operator
e. Rectifier P o w e r Unit PP-86(*)/TXC-1.
the tones that precede a facsimile trans-
Rectifier Power Unit PP-86/TXC-1, a component
mission. This is accomplished by re-
of Facsimile Sets AN/TXC-1 and AN/TXC-1A,
wiring the existing standby circuit to
will operate Facsimile Transceiver TT-1/TXC-1
include a loudspeaker in Facsimile Set
or TT-1A/TXC-1, but will not operate Facsimile
AN/TXC-1.
Transceiver TT-1B/TXC-1, TT-1C/TXC-1, TT-
(2) The receiving and standby circuits are
1D/TXC-1, TT-1E/TXC-1, or TT-1F/TXC-1,
modified.
unless modified.
Rectifier Power Units PP-
86A/TXC-1 and PP-86B/TXC-1 will operate
(1) The purposes of this modification are:
Facsimile Sets AN/TXC-1 through AN/TXC-1C.
-
(a) To eliminate motor failure by provid-
Rectifier Power Unit PP-86E/TXC-1 will operate
ing a new and improved type motor.
all models of the transceiver and has provision for
(b) To install a meter and a control for
supplying power for the dust removal blower
proper motor current indication and
supplied with Facsimile Set AN/TXC-1D.
adjustment.
f. Table MT-252A/TXC-1. Tables MT-252A/
(c) To prevent possible failure of amplifier
TXC-1 and MT-252B/TXC-1 are the same si e
tubes by installing a voltage dropping
as Table MT-252/TXC-1. The construction and
resistor and replacing tubes type
method of dismantling the three models differ
6AG5GT/G with tubes type 1635.
slightly.
(d) To prevent fluctuation of the input
g. Transceiver Differences.
Facsimile Trans-
signal to the motor power tubes by
ceiver TT-1F/TXC-1 is similar to Facsimile
incorporating an adjustment control,
Transceiver TT-1E/TXC-1 as listed in table I,
indicating meter, and new regulating
except in the following respects. In the -1F model,
lamp in the regulated B voltage
an automatic stop circuit is incorporated to
circuit.
de-energize the synchronous drive motor and
(2) Facsimile Transceivers TT-1/TXC-1 and
ground the amplified facsimile signal at the end
-1A and Rectifier Power Unit PP-
of drum travel. A duct has been placed to help
86/TXC-1 are the major items affected.
remove dust from the vicinity of the stylus during
d. MWO SIG 11-2258-3.
the record direct operation. The paper clamp bar is
(1) The purpose of this modification is to
plastic insulated to reduce spurious rf radiation
provide a replaceable worm and gear,
generated as the stylus passes across the clamp
when the worm and worm gear become
bar. This model includes R64, R71, R107, and
worn out, and when it is necessary to
R318 controls. Differences in Facsimile Trans-
replace the decoupling springs between
ceivers TT-1/TXC-1 through TT-1E/TXC-1
the synchronizing and start rotors with
are listed in table I.
springs of improved design.
(2) Facsimile motor model KBA-1 is the
11. Modifications
major item affected.
Certain parts of Facsimile Set AN/TXC-1(*)
e. MWO SIG 11-2258-5.
and Rectifier Power Unit PP-86/TXC-1 have been
(1) The purpose of this modification is to
modified as listed below. To determine whether
provide an improved type motor and new
or not the equipment in use has been modified,
mounting studs to be used on Facsimile
indications will be shown by markings on modified
Transceiver TT-1C/TXC-1 as made by
equipment or by the schematic diagrams found
Espey.
on the bottom plates of transceivers and rectifier
(2) Facsimile Transceiver TT-1C/TXC-1 is
the major item affected.
power units.
