Adc/Interface Section - HP 8560A Service Manual

An Automatic IF Adjustment, in analyzer firmware, sets center frequency and 3 dB
bandwidth of all filter poles through varactor and PIN diodes. The firmware also controls
crystal-pole symmetry and the step gain amplification.
The ADC/Interface Section is the link between the Controller Section and the rest of the
spectrum analyzer. It controls the RF, Synthesizer,and IF sections through address and
data lines on the W2 Control Cable (Analog Bus). Analog signals from these sections are
monitored by the ADC/Interface Section's ADC (Analog to Digital Converter) circuit.
The ADC/Interface section includes the A3 Interface Assembly, AlAl Keyboard, and AlA
RPG (front-panel knob). The A3 assembly includes log expand, video filter, peak detector,
track-and-hold, real-time DACs, RF gain DACs, +lO V reference, and ADC circuitry. The
assembly's digital section includes ADC ASM, sweep trigger, keyboard interface, RPG
interface, and analog bus interface circuitry.
General Troubleshooting 6-41