Watkins-Johnson Company WJ-8718-19/FE Instruction Manual page 199

MAINTENANCE WJ-8718-19/FE HF RECEIVER
Move the Frequency Counter clip lead to A5XA1 pin
A53. The Frequency Counter should read 1.000 kHz +/-
1 Hz.
Move the Frequency Counter clip lead to test point
A5A1A2 pin E6. The Frequency counter should read
40.000 kHz +/- 1 Hz.
If the signal in step 5 is incorrect, check the test
points given in Table 4-27 with an RF Voltmeter and
high impedance probe. When a faulty signal is
encountered, replace the key components indicated and
repeat the Checkout Procedure. Figure 6-25, 1st 6c 3rd
LO Synthesizer Schematic Diagram should be referred to
if additional signal tracing/fault isolation is necessary.
When the Time Base has been repaired and is operating
satisfactorily, deenergize the receiver and disconnect
test equipment, if no further tests are to be performed.
Table 4-27. Time Base Frequency Chart
IC PIN FREQUENCY
IC PIN FREQUENCY
U15 5
1 MHz U18
12 10 kHz
i
U15
6
1 MHz
U19
5
250 kHz
U15 8
2 MHz
U19
12 50 kHz
•
U15
12 200 kHz
U20
5
5 kHz
U17
12
40 kHz
U20
12
1 kHz
U18
5
500 kHz
U23 8
1 MHz
U18 8
1 MHz U23
11 1 MHz
4-46