increase of 2 or 3 db is Eastman 797. This paper
will not give the contrast given by the Royal
The signal attenuation over field wire such as
Bromide F1, but the lack of contrast can be
Wire W-110B is very high as compared with
compensated for by having the transmitting oper-
commercial telephone circuits. If only one circuit
ator transmit a signal of greater range between
is involved, make the line connection to the LINE
black and white. If the low density of a recording
JACK through the test cord provided with alli-
is the result of fogging of the recording lamp, the
gator clips. This permits the satisfactory trans-
fog or sputter usually can be removed partially
mission of signals over approximately 25 miles of
by heating the end of the tube in a flame. The
field line. If there are adjacent circuits, it may not
heating must be done by bringing the temperature
be possible to operate directly from the LINE
up gradually; the cooling also must be gradual.
JACK, because the facsimile signal will produce
The heat evaporates the deposited coating.
cross talk. The next best method of feeding the
line is to use the UC feed coil and connect the
line to the 6-volt receptacle.
Allowances
Caution: Never connect a commercial tele-
a. If there is no supply of stylus needles,
phone circuit to the LINE JACK.
ordinary steel phonograph needles may be used,
but they must be replaced often. Steel spring
wire with a diameter of approximately .010 inch
Troubles
may be used in an emergency. If the stylus
Telephone circuits carried in cables usually have
holder has become damaged beyond repair, a light
loading coils inserted in the cable at regular inter-
steel spring may be mounted in a fixed position
vals to improve the voice transmission character-
to serve as a stylus.
istics. The insertion of the loading coils produces
b. If Teledeltos or Timefax paper is not avail-
a distortion effect which is quite noticeable in some
able, readable copy can be made on black inter-
of the older type commercial circuits. If the
leaving paper used in the packing of transmission
received copy shows an out-of-focus or stutter
film.
effect, this degradation in many cases can be
traced to delay distortion on the telephone trans-
mission line. Under normal operating conditions,
Under some conditions, a radio transmitter will
nothing can be done to correct this trouble. The
feed back into a facsimile transceiver when the
only remedy is to obtain a better circuit.
transceiver is set for TRANSMIT. This feed-
back condition may occur when the facsimile set
is close to the radio transmitter. Feedback may
If Royal Bromide F1 paper is not available,
be caused by circulating currents through the
the recordings should be made on film and contact
ground system or in the general line connections.
prints made from the film. If too much time is
The feedback is indicated by a short contrast
required for this process, bromide enlarging papers
range when the radio set is turned on. Do not
may be used. Fairly good results can be obtained
attempt to operate when there is an indication of
from photostatic paper. Experiments must be
radio feedback; it must be eliminated. There is
made to determine the correct DB METER
no fixed rule for doing this. In most cases, proper
reading for the proper exposure. Most papers
isolation may be secured by trying different
require a higher signal level than Royal Bromide
coupling circuits and grounding systems between
F1. If it is necessary to go up to +4 or +5 db
the facsimile transceiver and the radio modulator
for recording, do not attempt to handle half-tone
input circuit.
copy. The shadows will be badly flattened be-
cause of the overloading of the amplifier.
Sparking at the recorder stylus sometimes causes
radio interference. Interference in radio reception
with New Transceiver
may be reduced by the use of proper grounding
systems. It is sometimes necessary to use a
Rectifier Power Unit PP-86/TXC-1, which is a
common ground for the radio receiver and the
component of Facsimile Sets AN/TXC-1 and
facsimile transceiver.
AN/TXC-1A, will not operate Facsimile Trans-
175
