TB 9-6625-1999-35
(2) Adjust A4R21 (fig. 3) until oscilloscope indication is slightly increased, then
slowly adjust in opposite direction until oscilloscope indication just collapses (R).
25. Maximum Carrier and Modulation Zero
Set
a. Performance Check
(1) Connect true rms voltmeter to RF OUTPUT 50Ω.
CAUTION
Throughout procedure, adjust ATTENUATOR VERNIER
control fully ccw before changing RANGE switch setting.
(2) Position controls as listed in (a) through (c) below:
(a) RANGE switch to 50KC-170KC.
(b) ATTENUATOR VERNIER control fully cw.
(c) MODULATION SELECTOR switch to EXT. AC.
(3) Rotate FREQUENCY control throughout range and record minimum voltage
(4) Repeat technique of (3) above for all RANGE switch settings. Minimum voltage
will be at least 1.05 V ac. Record minimum voltage.
(5) Set RANGE switch and adjust FREQUENCY control to value recorded in (4) above.
(6) Set MODULATION SELECTOR switch to CW. If true rms voltmeter indicates
a change in voltage output, perform b below.
b. Adjustments
(1) Adjust MAX CARRIER SET R60 (fig. 1) for a 1.05-V indication on voltmeter (R).
(2) Set MODULATION SELECTOR switch to EXT. AC.