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|  V806, V807, and V808. The trans-
fed through low-pass filter
FL1101, energized antenna relay
m i t t e r modulator amp1ifies the
signal and modulates the plate volt-
K101, and the directional coupler to
age supply to the transmitter
the antenna. Filter FM1101 mini-
driver and power amplifier stages
mizes radiation of undesired har-
monics, and directional coupler
V105, and V106, and the V106
provides an indication of the power
screen grid supply.
input to the antenna and the stand-
(2) The modulated rf output signal of
ing wave ratio on the transmission
the transmitter power amplifier is
line.
Section II. LOW-LEVEL STAGES
remaining components in this circuit oper-
ate as described for the receive function
(para 32).
a. On transmit, third oscillator V401B
functions as the initial frequency source.
Switch S402, driven by the 10-position, 0.1-
m c shaft, selects a crystal that corre-
sponds to the frequency to which the filter
V304 heterodynes the 3.0- to 3.9- mc signal
network consisting of Z401, Z402, and Z403
from V401A (para 49) with the 17.0- to
is tuned. For example, if the rt unit is tuned
26.0-mc output of second oscillator V305,
to a frequency, the last digit of which is 0.9
to produce the 20.0 to 29.9 first if. The op-
mc, 3.9-mc crystal Y410 is connected be-
eration of second oscillator V305 is iden-
tween ground and the grid of V401B through
tical in both the receive and transmit func-
contacts 9 and 10 of switch S402 and con-
tions. Refer to paragraph 28 for circuit
tacts 3 and 2 of relay K401 (energized on
component details.
transmit).
b. The 3.9-mc output of V401B is coupled
b. The 3.0- to 3.9-mc signal is coupled
through C417 into the cathode circuit of
to the control grid of V304 through plug
V401A. The remaining components within
P304, choke L312, and coupling capacitor
this oscillator circuit operate as described
C339. The 17.0- to 26.0-mc output of sec-
for the receive function (para 31).
ond oscillator V305 (para 28) is coupled
to the cathode of V304 and developed across
R317. Inductors L314, L315, and C348 form
a harmonic suppression network. The 3.0-
to 3.9-mc signal mixes with the 17.0 to 26.0
a. On transmit, V401A functions as a
signal in V304 to produce the 20.0- to 29.9-
buffer and amplifies the output of oscillator
mc sum frequency. Resistor R319 is the
V 4 0 1 B . Resistor R409 is disconnected
grid leak to ground circuit for V304. Re-
from the plate circuit by relay K401. This
sistor R317 provides cathode bias for V304
increases the plate voltage applied to
and provides coupling resistance for the
V401A, which, in turn, raises the plate cur-
17.0- to 26.0-mc signal from the second
rent through V401A and the level of the
output signal developed across cathode re-
sistor R405.
C.
Plate voltage for V304 is supplied
from the +125-volt supp1y through J3,
b. The input signal is applied across grid
P 3 0 1 , feedthrough capacitor C334, re-
resistor R406. The output voltage is taken
sistor R314, and choke L309. Screen grid
off cathode resistor R405, coupled through
voltage is supplied through voltage drop-
C411, filter Z403, Z402, and Z401, and ap-
p i n g resistor R316. Capacitors C342
plied to first transmitter mixer V304. The
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