TM 11-6625-821-45
resistance of resistors R304 and R305. In position
netted across CONTROL TEST terminals J3 and
6, the CONTROL TEST switch connects CON-
J4 checks continuity of the LOOP switch and mea-
TROL TEST terminal J3 to B of potentiometer
sures the resistance of resistors R306 and R307.
R301B through front switch wafer S4B. When the
d. Bfo, Rf Gain Control, and Audio Gain Control
function switch is set to ADF, the ohmmeter mea-
sures the resistance of the bridged-T network con-
across CONTROL TEST terminal J3 and J4, the
sisting of potentiometers R301A and R301B and
test set provides resistance and continuity checks
resistors R304 and R305.
of the beat frequency oscillator (bfo), rf gain con-
trol, and audio gain control circuits in the control
checks on the function control circuit in the con-
unit. RECEIVER-CONTROL switch S4 connects
trol unit are made with an ohmmeter connected
CONTROL TEST jack J4 to pins f and T of connec-
across CONTROL TEST terminals J3 and J4 and
tor P301. When set in position 2, CONTROL TEST
with the CONTROL TEST switch set in positions
switch S3 connects CONTROL TEST terminal J3
7 through 10 RECEIVER-CONTROL switch S4
to the bfo circuit through front switch wafer S4A.
connects CONTROL TEST terminal J4 to pin L of
Continuity of switch S301 in the control unit can
connector P301. In position 7, the CONTROL
now be checked. In position 3, the CONTROL
TEST switch connects CONTROL TEST terminal
TEST switch connects CONTROL TEST terminal
J3 to pin K on connector P301 through the front
J3 to the rf gain control circuit through front
and rear wafers of switch S4C. The operation of
switch wafer S4C. When the control unit function
rear switch S302B is then checked. When the
switch is set to ADF, continuity of switch S302A is
CONTROL TEST switch is set to positions 8, 9,
checked. When the function switch is set to ANT,
and 10, the operation of front switch wafer S302B
the resistance between B and C of potentiometer
is checked. In position 8, CONTROL TEST termi-
R301C is checked. When the function switch is set
nal J3 is connected through rear switch wafer S4A
to LOOP, the resistance of resistor R303 is series
to the ADF function control line of the control
with the resistance between B and C of poten-
unit. When the control unit function switch is set
tiometer R301C is checked. When the CONTROL
to each of its four positions, continuity will be
TEST switch is in position 4, CONTROL TEST
indicated on the ohmmeter in positions ANT and
terminal J3 is connected to A of potentiometer
LOOP and infinity indicated in positions OFF and
R301C through rear switch wafer S4C. The resis-
ADF. When the CONTROL TEST switch is in
tance between A and C of potentiometer R301C is
position 9, CONTROL TEST terminal J3 is con-
measured when the function switch is set to ADF
nected to the ANT function control through front
or ANT. When the function switch is set to LOOP,
switch wafer S4A. The ohmmeter will then indi-
the resistance of resistor R303 in series with the
cate continuity when the function switch is set to
resistance between A and C of potentiometer
ADF and LOOP and indicate infinity in positions
R301C is measured. The audio gain control cir-
OFF and ANT. When the CONTROL TEST
cuits are checked with the CONTROL TEST
switch is in position 10, CONTROL TEST terminal
switch in positions 5 and 6. In position 5, CON-
J3 is connected to the LOOP function control line
TROL TEST terminal J3 is connected to the audio
through rear switch wafer S4A. The ohmmeter
out terminal on the control unit through rear
will indicate continuity when the function switch
switch wafer S4C. When the function switch is set
is set to ADF and ANT and indicate infinity in
to ADF, the resistance between B and C of poten-
positions OFF and LOOP.
tiometer R301A is measured. When potentiome-
f. Range Control Circuit (fig. 5-10). continuity.
ter R301A is in its fully counterclockwise position,
and resistance checks on the range control circuit
the resistance measured in between B and C of
in the test set are made with an
potentiometer R301A in parallel with the series
1-8
Change 2
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