Chapter 6 331
General Troubleshooting
Block Diagram Description
RF Section
The RF Section includes the following assemblies:
• A7 LODA (LO distribution amplifier)
• A8 low band mixer
• A9 input attenuator
• A10 tracking generator (Option 002)
• A11 YTO (YIG-tuned oscillator)
• A13 second converter
• A14 frequency control assembly (also in synthesizer section)
• A15 RF assembly (also in synthesizer section)
• FL1, FL2 low-pass filters
The RF section converts all input signals to a fixed IF of 10.7 MHz. The
RF section microcircuits are controlled by signals from the A14
frequency control and A15 RF assemblies.
The HP 8560E/EC spectrum analyzer uses triple conversion to produce
the 10.7 MHz IF and a fourth conversion used only in resolution
bandwidths ≤100 Hz. A8 low band mixer up-converts the RF input to a
first IF of 3.9107 GHz. A13 second converter down-converts the 3.9107
GHz IF to an IF of 310.7 MHz. A third conversion on the A15 RF
assembly down-converts the second IF to the 10.7 MHz third IF. A
fourth conversion on the A4 log amplifier assembly down-converts the
third IF to the 4.8 kHz fourth IF used only in resolution bandwidths
≤100 Hz.
A7 LODA
The A7 LODA (LO distribution amplifier) levels the output of the A11
YTO and distributes the power to the front-panel 1ST LO OUTPUT, A8
Low Band Mixer, Option 002 Tracking Generator, and A15U100
Sampler. The leveling circuitry is on the A14 Frequency Control
Assembly.
A8 Low Band Mixer
A8 low band mixer is dc-coupled and contains a limiter. In spectrum
analyzers with serial number prefix 3632A and greater, the A8 low
band mixer also contains an LO buffer amplifier and an IF preamplifier.
A14 frequency control board assembly provides power for these
amplifiers via cable harness W12.
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