Chapter 8 409
ADC/Interface Section
A3 Assembly Control Circuits
6. Press PRESET and set the controls as follows:
Span .................................................................................0Hz
Trigger ...................................................................... SINGLE
7. Monitor A3U401 pin 3 (LR_STB) with an oscilloscope or logic probe.
This is the strobe for the A15 RF assembly.
8. Press
AUX CTRL and REAR PANEL and check that pulses occur when
toggling between
10 MHz INT and 10 MHz EXT.
9. Monitor A3U401 pin 5 (LF_STB) with an oscilloscope or logic probe.
This is the strobe for the A14 frequency control assembly.
10.Press
AMPLITUDE and check that pulses occur when toggling
between
ATTEN settings of 10 and 20 dB.
11.Monitor A3U401B pin 7 (LIF_STB) with an oscilloscope or logic
probe. This is the strobe for the A5 IF assembly.
12.Press
AMPLITUDE and check that pulses occur when toggling
between
REF LVL settings of −10 dBm and −20 dBm.
13.Monitor A3U401B pin 9 (LLOG_STB) with an oscilloscope or logic
probe. This is the strobe for the A4 log amplifier/cal oscillator
assembly.
14.Press AMPLITUDE and check that pulses occur when toggling
between
LINEAR and LOG DB/DIV.
Interface Strobe Select
Refer to function block K of A3 Interface Assembly Schematic Diagram
(sheet 3 of 6) in the 8560 E-Series Spectrum Analyzer Component Level
Information.
Interface strobe select generates the various strobes used by circuits on
the A3 Interface Assembly. Table 8-9 on page 410 and Table 8-10 on
page 410 are the truth tables for demultiplexers A3U410 and A3U500.
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