TM 11-5826-225-35
g. Adjust the frequency of the signal gen-
(2) GONIO DRIVE switch to ON.
erator to 200 kc (the same as the receiver) as
determined by a zero beat in the headset.
d. Refer to figure 2-7 and note connections for
resistor R133. Unsolder and disconnect both leads
h. Set the BFO-OFF switch on the control
of R133.
unit to OFF.
i. Adjust the output of the signal generator
e. Select a value for resistor R133 (1500, 1800,
to 40 microvolt.
2200, 2700, or 3900 ohms) and connect to terminals
noted in step d.
j. Loosen the locknut on R131 (fig. 2-8).
k. Adjust R131 fully clockwise. The needle
f. Set the test set DC POWER switch to ON and
of the BEARING INDICATOR on the test set
the control unit LOOP L-R switch to the first de-
should fluctuate several degrees on either side
tent toward R.
of the actual indication.
Note. Resistor R131 is the adf hunt control. It is used
g. Record the time required for the test set
to adjust the amount of adf needle activity (fluctuation
BEARING INDICATOR to rotate 180 degrees
about the actual bearing indication). When R131 is
clockwise.
fully clockwise, the time required to obtain a bearing is
minimum but the needle activity is maximum. As R131
is turned counterclockwise, the needle activity decreases,
h. Repeat steps e through g to select a value for
but the time required to obtain a bearing increases and
R133 that will provide a slow slew speed of 24 to 36
the resolution (accuracy) of the indication may be
seconds for a 180-degree clockwise rotation.
degraded. The amount of needle activity can be set as
desired M long as the resolution (l below) and the
i. After the proper resistor value is determined,
speed required to obtain an indication ( m below) are
set the test set DC POWER switch to OFF.
within the prescribed limits.
Replace R133 with new value.
L Check. the resolution as follows:
(1) Note the indication of the BEARING
3-20. Adjustment of Adf Hunt Control
INDICATOR on the teat set.
(2) Adjust the LOOP control on the con-
a. Connect the equipment as shown in figure
trol unit to the L side, and then release
2-2. It is not necessary to connect the audio
the LOOP control. Note the indication
output meter.
of the BEARING INDICATOR when
b. Set the switches on the control unit as
the needle of the BEARING INDI-
follows :
CATOR resolves itself to its previous
position.
(1) BFO-OFF switches to BFO.
(3) Adjust the LOOP control to the R
(2) Function switch to ADF.
s i d e , and then release the LOOP
(8) GAIN control fully clockwise.
control. Note the indication of the
BEARING INDICATOR when resolv-
c. Set the switches on the test set as follows:
ing is complete.
(1) DC POWER switch to ON.
(4) The indications in (2) and (3) above
(2) R E C E I V E R - C O N T R O L switch to
should not exceed the indication in ( 1 )
RECEIVER.
above by more than 2 degree.
(3) GONIO DRIVE switch to ON.
m. Check the bearing speed as follows:
(1) Adjust the TUNE control on the con-
d . Set the 150PF-270PF switch on the
trol unit for 300 kc.
sense antenna adapter to 150PF.
(2) Set the BFO-OFF switch on the con-
trol unit to BFO.
e. Set the range switch on the control unit
(9) Adjust the frequency of the signal
to 190-400, and adjust the TUNE control on
generator to 300 kc as determined by
the control unit for 200 kc on the FREQUEN-
a zero beat in the headset. It may be
CY indicator.
necessary to increase the output level
of the signal generator while zero
f. Adjust the output of the signal generator
beating.
to 1000 microvolt, no modulation.
3-29
Change 5
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