5. LINEAR AMPLIFIER COMPENSATION
4 INDEX LIGHT SELECTOR A3S1-IF
Index light selection wafer A3S1-1F, on the INPUT
Part of amplifier compensation, for 10 dB steps of INPUT
ATTENUATION control, selects the index light associated
with the LOG REF LEVEL/ LINEAR SENSITIVITY control in
Refer to IF Section Operating and Service Manual for detailed
the analyzer IF section. In LOG mode, the selected index
lamp is opposite the scale factor on the LOG REF LEVEL
control that corresponds to full-scale deflection on the display.
In LINEAR mode, the selected index light is opposite the
LINEAR SENSITIVITY PER DIVISION scale factor. Lights
Connect the ground lead of the HP 410C to fuse Fl. Connect
DS1 through DS6 provide a moveable index point, positioned
the other lead to P3 pin 7. Meter should indicate continuity at
by the INPUT ATTENUATION control, corresponding to the
50 dB, 30 dB, and 20 dB positions of INPUT ATTENUATION
analyzer's overall gain and amplitude scale calibration factor.
control. Move connection from P3 pin 7 to P3 pin 8. Meter
should indicate continuity at 40 dB, 20 dB, and 0 dB positions
of INPUT ATTENUATION control. If readings are correct,
Turn instrument off. Connect the ground lead of the HP 410C
trouble should be in IF Section wiring. If indications are
incorrect, check S11R and 8553B wiring.
check for a reading of 147 ohms at connector pins of P3 as
follows: 0 dB pin 33, 10 dB pin 34, 20 dB pin 35, 30 dB pin 9,
40 dB pin 10, and 50 dB pin 11. If the 147 ohm reading is not
obtained at any setting R10 or Fl may be defective. If the
Provides power to 1121A Active Probe. Probe provides
reading is obtained at some, but not all positions, switch
section S1 1F or wiring is probably defective.
circuits. Power available for probe use is +15V (5%) and --
Simplified Test Procedure Tree