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WJ-8718A/MFP
TABLE 4-5
occurs, R2 should be adjusted to decrease VR voltage until all segments are of the same
intensity.
To properly adjust R2, connect an oscilloscope (reference equipment list, WJ-8718
Series HF Receiver Instruction Manual) to J2, and adjust R2 for an oscilloscope display of
approximately 7 Vdc with a maximum ripple of 500 mV p-p.
R2 is adjusted clockwise to
increase voltage and counterclockwise to decrease voltage.
4.1.2.2
Scan
TIlreshold Adjustment (R7)
Potentiometer R7 controls the range of the signal strength levels, so that they fall
within the required specifications.
Table
4-5
lists the threshold level codes and their
corresponding signal strength levels in dBm.
Table
4-5.
TIlreshold Level
Codes
Keypad Entry
Thr-eshold
Code
Level
1
-110 dBm
2
-100 dBm
3
-90 dBm
4
-80 dBm
5
-70 dBm
6
-60 dBm
7
-50 dBm
8
-30 dBm
NOTE:
±l
0 dBm tolerance.
To locate R7, consult Figure
5-10
(location of components) and Figure
6-5
(schematic diagram).
Before alignment, the potentiometer should be turned completely
counterclockwise. The scan threshold adjustment itself is done with the receiver in scan mode.
To align R7 to the specified range, use the following procedures:
1.
Connect the test equipment as shown in Figure
4-2
and energize all
equipment.
2.
Tune the signal generator to provide a 15 MHz, CW signal at
-30 dBm.
3.
Store the following receiver parameters in memory channel 87:
Detection Mode
Bandwidth
Gain Mode
Tuned Frequency
Threshold
Dwell
4.
Store 15.1 MHz in channel 88.
CW
16 kHz
AGC FAST
14.9 MHz
8
1
4-7
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