TB 9-6625-003-35
27. Bolometer Bias
a. Performance Check
(2) Connect dc voltmeter (A4) to resistance standard, using cable (B5).
(3) Set RANGE switch to 0 (zero), INPUT SELECTOR switch to BOLO HIGH, and
turn and hold BIAS CHECK control fully cw. If TI does not indicate 8.7 mA on BOLO BIAS
scale, and dc voltmeter does not indicate between 1.69 and 1.79 V, perform b(1) and (2)
below.
(4) Set INPUT SELECTOR switch to BOLO LOW and turn and hold BIAS CHECK
control fully cw. If TI does not indicate 4.3 mA on BOLO BIAS scale and dc voltmeter does
not indicate between 0.83 and 0.88 V, perform b(3) below.
b. Adjustments
(1) Turn and hold BIAS CHECK control in fully cw position while adjusting BOLO
BIAS ADJ HIGH (rear panel) for an 8.7-mA indication on BOLO BIAS scale.
(2) Adjust R101 (fig. 7) until dc voltmeter indicates 1.74 V (R).
Figure 7. Model 415D- bottom view.
(3) Turn and hold BIAS CHECK control in fully cw position while adjusting BOLO
BIAS ADJ LOW (rear panel) until TI indicates 4.3 mA on BOLO BIAS scale.
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