86 Chapter 2
Block Diagrams
Miscellaneous
Front Frame
The front frame assembly contains the following four assemblies.
A1 Keyboard
The keyboard allows entry of keyboard characters, immediate
activation of some features including the print, restart, and display
navigation features, and selection of some softkey menus.
A2 Flat Panel Display
The LCD display assembly provides annotation, graticule, and trace
information, as processed by the CPU though the front panel interface
board. Two backlights are used to illuminate the LCD display. The LCD
display will function when only one backlight is working. The
backlights can be easily replaced, and should be replaced as a pair.
A3 Front Panel Interface Assembly
The front panel interface board interprets which key has been pressed,
and provides voltage supplies to the inverter boards, the RPG tuning
circuitry, and the probe power bias voltage outputs. The front panel
interface assembly is comprised of three boards. The A3A1 and A3A2
inverter boards are identical. The inverter boards provide a stepped-up
voltage to both backlights on the LCD display.
A4 Disk Drive
The disk drive is used to download information from a 3.5 inch floppy
disk to instrument memory, and to load information from the
instrument onto a floppy disk.
A27 Rear Panel
Four connectors are located on the rear panel of the instrument.
External Reference. The external reference allows you to select an
external reference to phase lock all oscillators in the instrument. You
can select any external reference frequency between 1 and 30 MHz. The
A18 reference assembly then converts any external reference frequency
to 10 MHz. A green Ext Ref message on the front panel annunciator
bar indicates that the instrument is locked to the external reference. A
red Ext Ref message indicates that the external reference has been
selected but that the instrument is not locked.
10 MHz out (switched). The 10 MHz out allows you to lock other test
equipment to the same frequency reference that is being used by the
transmitter tester. Once the 10 MHz out is set to an On state, it will
persist an On state until an Off state is selected.
Trigger out (1 + 2). These two trigger outputs enable you to trigger
external test equipment.
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