
Model 8640B
TM 9-4935-601-14-7&P
CHANGE 5
Page 6-13, Table 6-3:
Change A8MP41 to 08640-40067.
Page 6-37, Table 6-3:
Change A26A4S1 to 3101-0860.
CHANGE 6
NOTE
See paragraph 7-75 for recommended instrument modification.
Page 1-6, paragraph 1-65:
Delete the following:
Spare power supply regulator integrated circuit.
Page 5-2, paragraph 5-21:
Add step h.
A8A1C8 Selection.
Capacitor may or may not be used; its value will always be 2.2 pF. Select as
follows:
1.
Set COUNTER MODE: Source to EXT 0-550, RANGE to 256-512 MHz, and OUTPUT LEVEL to +10
dBm.
2.
Connect RF OUTPUT to COUNTER INPUT.
3.
Turn FREQUENCY TUNE cw and observe frequency increase towards 550 MHz on the counter.
4.
Repeat step 3 for OUTPUT LEVEL settings of 0 dBm and -7 dBm. If count becomes erratic or displays
zero count, as frequency approaches 550 MHz, add capacitor between pins 13 and 16 of A8AlU1.
Page 5-2, Table 5-1:
Add the following:
Service
Range of
Component
Sheet
Values
Basis of Selection
A8A1C8
18
2.2 pF
See paragraph 5-21
Page 6-13, Table 6-3:
Add A8A1C8 0160-3872 CAPACITOR-FXD 2.2 PF + 0.25 PF 200 WVDC.
Page 6-34, Table 6-3:
Change A26A2CR9 to 1901-0539 DIODE, SCHOTTKY, SI.
Change A26A2CR13 to 1901-0539 DIODE, SCHOTTKY, SI.
7-27
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