TB 9-4931-321-35
13. Expanded
Range Linearity and Accuracy
a. Performance Check
(1) Reduce function/arbitrary generator output amplitude and adjust ratio
transformer to 1.000000.
(2) Set RANGE-DB switch to 0 and EXPAND to 0.
(3) Adjust function/arbitrary generator output amplitude to obtain an on-scale
indication on TI meter
(4) Adjust function/arbitrary generator output amplitude and GAIN controls to
obtain a 0 (zero) dB indication on TI meter 0 (zero) to 2 dB scale.
(5) Adjust ratio transformer to obtain 0.5 dB indication on TI meter 0 (zero) to
2 dB scale.
(6) If ratio transformer does not indicate between .887160 and .895360, perform b
(1) through (3) below.
(7) Adjust ratio transformer to obtain TI meter indications listed in table 4. If ratio
transformer does not indicate within specified limits, perform b (4) and (5) below.
Test instrument
Ratio transformer
indication
indication
(0 to 2 dB scale)
Min
Optimum
Max
1
.790684
.794328
.798001
1.5
.704700
.707946
.711212
2
.628063
.630957
.633870
(8) Repeat (1), (3), and (4) above.
(9) Adjust ratio transformer to .630957 and set EXPAND switch to 2.
(10) Adjust ratio transformer to obtain a 0 (zero) dB indication on TI meter 0 (zero) to
2 dB scale. Ratio transformer will indicate between .623735 and .638266.
(11) Repeat technique of (9) and (10) above, using settings listed in table 5. Ratio
transformer indications will be within specified limits.
Initial ratio
Test instrument
Ratio transformer
EXPAND
transformer
indication
setting
switch position
Min
Max
.398107
4
.393551
.402712
.251189
6
.248313
.254097
.158489
8
.156675
.160325
b. Adjustments
(1) Adjust ratio transformer to .891251.
(2) Adjust A3R57 (R357 or R57) (fig. 1) to obtain 0.5 dB indication on TI meter 0
(zero) to 2 dB scale (R).