TB 9-4920-451-24
15. Capacitance
a. Performance Check
(1) Set switches as listed in (a) through (c) below:
(a) DISPLAY SELECT switch to CAP (pF).
(b) CAPACITANCE FUNCTION switch to A/C TEST COMP.
(c) CAPACITANCE RANGE (pF) switch to HIGH ADJ.
(2) If digital indicator does not indicate high value stamped on CAP STANDARDS
placard on front panel, adjust CAP STANDARD HIGH ADJ control (front panel).
(3) Set CAPACITANCE RANGE (pF) switch to LOW ADJ. If digital indicator
does not indicate the low value stamped on CAP STANDARDS placard on front panel,
adjust CAP STANDARD LOW ADJ control (front panel).
(4) Repeat (2) and (3) above until no further adjustment is required.
(5) Set CAPACITANCE RANGE (pF) switch to 8000, 4000, 1000, and 200 ranges
respectively. If digital indicator does not zero on each range setting, perform b below.
(6) Connect variable capacitor low to COAX A, and variable capacitor high (upper
range or lower range) to COMP C. Measure lead capacitance and record.
(7) Set CAPACITANCE RANGE (pF) switch to 200 pF.
(8) Set variable capacitor to 35 pF. If TI does not indicate between 34 and 36 pF
plus lead capacitance recorded in (6) above, perform adjustments as listed in table 6.
(9) Repeat technique of (8) above using settings and indications in table 6. If TI does
not indicate within limits specified, perform adjustments listed in table 6.
Table 6. Capacitance Check
Test Instrument
Variable capacitor
or
RANGE
Adjustments
standard capacitor
settings
Indications
(pF)
Min
Max
200
100
99.0
101.0
R21
1000
500
495.0
505.0
R20
4000
1000
980.0
1020.0
---
4000 1
3000
2980.0
3020.0
R19
8000
5000
4960.0
5040.0
---
8000
7000
6960.0
7040.0
---
1Subsitute
capacitance standard for variable capacitor.
b. Adjustments. Adjust R85 (fig. 2) on 200 pF range and R86 on 1000 pF range for a
zero indication then repeat (2) through (4) above.