TM 11-6625-622-40
c o n n e c t o r J3. The transmission line passes
by way of pins P, R, S, and T of jack J19, and
through the center of, and serves as the primary
pins 49 through 52 of connector J1. The 0.001-
for, toroidal transformer T1. The rf current in-
MHz control, S4, selects aportion of the receiver-
duced in transformer T1 produces a voltage that
transmitter operating frequency in 0.001-MHZ
divides equally across resistors R1 and R2. The
steps. The 0.001-MHZ control is connected to
voltages developed across resistors R1 and R2
the receiver-transmitter byway of pins F, G, H,
with respect to ground are 180 out of phase.
and J of jack J19, and pins 38 through 41 of
Capacitors C5 and C6 serve as bypass capacitors.
.
connector J1. All frequency control signals go to
The rf voltage on the transmission line is coupled
the rf translator module of the receiver-transmit-
by variable capacitors C1 and C2 to the cathodes
ter. The rf sensitivity of the receiver-transmitter
of diodes CR1 and CR2, respectively. As a result,
is controlled from the control unit by RF SENS
when the rf load is 50 ohms resistive, equal volt-
potentiometer R1. Potentiometer R1 is connected
ages of the same phase are applied to the diode
from jack J19 pin Z, to the receiver-transmitter
cathodes and equal voltages of opposite phase are
rf translator module, through connector J1 pin
applied to the diode anodes. When a mismatch
30. Frequency band information is sent to the
occurs at the 50-ohm transmission line output,
antenna coupler from the control unit. The con-
nections are as follows: jack J19 pins f, g, and
power is reflected back; then the voltages de-
h, to ANT. CPLR connector J6 pins B, C, and
veloped across R1 and R2 represent the vector
D, respectively. The sideband selection line from
sum of two components, one of which is pro-
mode selector switch S5A in the control unit to
portional to the forward wave rf current and the
the sideband selection relay of the receiver-trans-
other proportional to the reflected wave rf cur-
rent. Similarity, the capacitively coupled voltages
mitter passes through the test unit as follows:
at diode cathodes represent the vector sum of the
from jack J19 pin j, to switch S6 terminal 12;
forward wave and reflected wave voltage compo-
and from switch S6 terminal 11, the signal is
nents. Variable capacitors C1 and C2 are factory-
passed to the receiver-transmitter through con-
adjusted so that the magnitude of the forward
nector J1 pin 24. The AM relay line from mode
wave voltage and forward wave current compo-
selector switch S5A in the control unit to the
nents is equal for a 50-ohm resistive load. As a
A M relay of the receiver-transmitter passes
result, the magnitude of the reflected wave volt-
through the test unit as follows: from jack J19
age and reflected wave current components also
pin i, to switch S6 terminals 9 and 10; from
is equal.
switch S6, terminal 8 to the receiver-transmitter
through connector J1 pin 25. The continuous-
b. When variable capacitors C1 and C2 are
wave (cw) key line circuit from mode selector
adjusted properly, the phase relationship between
s w i t c h S5B to the cw relay of the receiver-
the various components is such that the voltage
transmitter passes through the test unit as fol-
across diode CR1 is equal to the resultant of the
lows: from jack J19 pin p to the receiver-trans-
forward wave components. The voltage across
mitter, through connector J1 pin 31. Another
diode CR2 is equal to the resultant of the re-
branch of the cw key line circuit goes from mode
flected wave components. When the transmission
selector switch S5A, through jack J19 pin k, to
line is terminated in a 50-ohm resistive load,
CW KEY switch S8. If switch S8 is not in the
the voltages at the anode and cathode of diode
center position, the cw key line circuit is ground-
CR1 are equal in magnitude and opposite in
ed. The on-off control line circuit from the re-
phase. The voltage drop across diode CR1 is the
c e i v e r - t r a n s m i t t e r to the control unit passes
sum of those voltages or twice the value of each.
through the test unit as follows: from interlock
Therefore, diode CR1 acts as a detector and pro-
r e l a y K9 of the receiver-transmitter, through
duces a resultant dc voltage which is proportional
connector J1 pin 59, to switch S6 terminal 5;
to the amplitude of the forward voltage and cur-
from switch S6 terminal 6, through jack J19 pin
rent phase or sum. The dc voltage is applied to
q, to switch S5B. The wire which would normally
the RF OUTPUT meter circuits to provide an
be used to supply power to the panel lights in
indication of rf forward power on the transmis-
the control unit passes through jack J19 pin d
sion line. At the same time, the inductively and
and terminates in the test unit.
capacitively coupled voltages across diode CR2
are of equal magnitude and in phase. Therefore,
2-9. Directional Wattmeter
zero dc output voltage is obtained from diode
CR2. When a mismatch on the transmission line
a. The rf input is applied to DIR WM RF IN
causes reflected power waves, the voltages are no
2-3
