(1) Transmitting. With the selector switch
ohms, since the use of tube 5652 as a photocell in
set in the TRANSMIT or SET RANGE
these models precludes the passage of undesired
position, the control grid of V12 receives
low frequencies through the amplifier strip. In
the signal coupled from the plate of tube
Facsimile Transceiver TT-1E/TXC-1 and TT-
V11 through C39 and developed across
1F/TXC-1, capacitor C35 is 240 f. The cathode
R59, the transmitting half of the dual
of V11 is not bypassed; sufficient signal is im-
G A I N control. The slider on R59
pressed on the grid of this tube because of the
selects the portion of voltage across the
increased values of coupling capacitor C35 and
resistor which is to be applied to the
grid resistor R55 to make it unnecessary to have
grid of V12. Resistors R61 and R62 in
additional gain by means of cathode bypassing.
series constitute a voltage divider across
Screen current is supplied through screen resistor
the input circuit of V12. Half of the
R57, and the screen is bypassed to ground by
V12 grid voltage is applied from the
C37. Regulated plate voltage is applied through
junction of R61 and R62 through capac-
R58, the plate load resistor. The amplified
itor C41 to the grid of the meter amplifier
1,800-cycle signal developed across R58 is applied
half of V13 (figs. 55 and 56). Tube V12
through C39 to output GAIN control R59, and
is biased by cathode current flowing
through C38 to the grid circuit of the signal am-
through cathode resistor R63, which is
plifier half of dual triode tube V13.
bypassed at audio frequencies by C40.
Transformer T2 is the output trans-
third signal amplifier is a triode-connected, Class
former for stage V12. Plate current
A signal amplifier, using a 7C5 tube, which serves
flows through the primary from the reg-
as the transceiver output amplifier on transmitting
ulated +250-volt supply. Signal varia-
and as a driver stage for V14 (Class B stage) on
tions at the plate of V12 cause signal
photo recording. Tube V12 is in the facsimile
signal circuit only when the selector switch is in
voltages to be induced in the two
the TRANSMIT, SET RANGE, or RECORD
secondaries of T2. In the TRANSMIT
position of the selector switch only,
PHOTO position. The stage amplifies modulated
secondary No. 1 is connected to the
1,800-cycle signals in both transmitting and re-
LINE JACK, one side of which is
ceiving functions. The stage is also used in the
talk-back circuit of Facsimile Transceivers TT-
grounded through section IVL of the se-
1A/TXC-1 through TT-1F/TXC-1.
lector switch, and secondary No. 2 is
