Anritsu MG3702xA Series, Maintenance Manual

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2-5 RF Deck Assemblies Chapter 2 — Functional Description
2-10 PN: 10370-10372 Rev. B MG3702xA MM
External Leveling
In the external leveling mode, an external detector or power meter monitors the RF output level of the
MG3702xA instead of the internal level detector. The signal from the external detector goes to the A6
ALC PCB assembly from the rear panel input. The ALC controls the RF power output level as previously
described.
Power Sweep
In this mode, the CPU has the ALC step the RF output through a range of levels specified by the user.
This feature can be used in conjunction with the sweep mode to produce a set of identical frequency
sweeps, each with a different RF power output level.
Pulse Modulation Operation
During pulse modulation, the ALC level amplifier (A6 ALC PCB) is operated as a sample/hold amplifier.
The level amplifier is synchronized with the modulating pulses from the A8 Function Generator or A13
Pulse Generator PCB so that the ALC loop effectively operates only during the ON portion of the pulsed
modulated RF output.
Pulse Generator Operation
The A6 built in Function Generator provides the internal pulse generating function for the MG3702xA. It also
interfaces external pulse inputs from the rear panel connector to the pulse modulator driver in the external
mode.
The A6 internal pulse generator produces a pulse modulation waveform consisting of single, doublet, triplet, or
quadruplet pulse trains at variable pulse rates, widths, and delays. In addition, the A6 internal pulse
generator produces a sync pulse and video pulse output that goes to the rear panel. The sync pulse output is for
synchronizing auxiliary instruments to the internally generated pulse; the video pulse is a TTL level copy of
the RF output pulse; and the sample/hold signal synchronizes the ALC loop to the ON portion of the pulse
modulating waveform.
2-5 RF Deck Assemblies
The primary purpose of the RF deck assembly is to generate CW RF signals and route these signals to the front
panel RF OUTPUT connector. It is capable of generating RF signals in the frequency range of
10 MHz to 20 GHz.
The series MG3702xA use a VCO and Multiplexer. All other frequencies are derived from the fundamental
frequencies generated by this oscillator, as follows:
• RF output frequencies of 0.01GHz to 2 GHz are developed by digital down converting the fundamental
frequencies of 2.0 to 4.4 GHz.
• RF output frequencies of 2 to 20 GHz are produced directly from the VCO and Multipliers.
RF Deck Configurations
All MG3702xA RF deck assemblies contain a VCO oscillator and multiplier, a switched filter assembly, and a
directional coupler. Beyond that, the configuration of the RF deck assembly varies according to the particular
options installed.
Refer to the block diagrams in
Figure 2-4 , and Figure 2-5 through Figure 2-7 , which show the various RF deck
configurations and include all of the common RF components found in the series MG3702xA RF deck
assemblies. Refer to these block diagrams while reading the following paragraphs.