Agilent Technologies 856290216 service manual RF Section, A7 Sloda

RF Section

The RF section includes the following assemblies:

A7 SLODA (switched LO distribution amplifier)

A8 low band mixer

A9 input attenuator

A10 YIG-tuned filter/mixer (RYTHM)

All YTO (YIG-tuned oscillator)

Al3 second converter

Al4 frequency control assembly (also in synthesizer section)

Al5 RF assembly (also in synthesizer section)

FLl, 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 Al4 frequency control and Al5 RF assemblies.

Band 0 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 kHz to 2.9 GHz Bands 1 through 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2.75 to 13.2 GHz

Band 0 uses triple conversion to produce the 10.7 MHz IF and a fourth conversion used only in the digital resolution bandwidths (5100 Hz). A8 low band mixer up-converts the RF input to a first IF of 3.9107 GHz. Al3 second converter down-converts the 3.9107 GHz IF to an IF of 310.7 MHz. A third conversion on the Al5 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 the digital resolution bandwidths (5100 Hz).

Bands 1 and 2 use double conversion. A third conversion is used for the digital resolution bandwidths (<lo0 Hz). A10 YIG-tuned filter/mixer (RYTHM) down-converts the RF input to a first IF of 310.7 MHz. Although this IF passes through the Al3 second converter, it bypasses the second mixer. The second conversion on the Al5 RF assembly down-converts the 310.7 MHz IF to 10.7 MHz. A third conversion on the A4 log amplifier assembly down-converts the second IF to the 4.8 kHz third IF used only in the digital resolution bandwidths (5100 Hz).

A7 SLODA

The A7 SLODA ( switched LO distribution amplifier) levels the output of the All YTO and distributes the power to the front-panel First LO OUTPUT, A8 low band mixer, A10 YIG-tuned filter/mixer, and A15UlOO sampler. The leveling circuitry is on the Al4 frequency control assembly.

A8 Low Band Mixer

A8 low band mixer is ac-coupled and contains a limiter. The high band mixing is done in the A10 YIG-tuned filter/mixer. A PIN diode switch in A10 directs the RF input to the appropriate mixer. A PIN diode switch in A7 SLODA directs the first LO to the appropriate mixer. Low band mixer power is provided by the Al4 frequency control assembly.

General Troubleshooting 7-43