Mechanical Characteristics; Equipment Supplied - Watkins-Johnson Company WJ-8718-19/FE Instruction Manual

GENERAL DESCRIPTION WJ-8718-19/FE HF RECEIVER
1.2 MECHANICAL CHARACTERISTICS
The receiver is 19 inches wide and occupies one full rack width in a
standard 19-inch equipment rack. The receiver occupies 5.25 inches of vertical space,
and extends 19.6 inches into the rack. The main chassis, front, rear, top, and
internal compartment panels are constructed of aluminum. Side panels are 0.25 inch
thick aluminum plate, the front panel is a 0.19-inch thick aluminum plate, and the
rear panel, main deck, and internal partitions are stamped aluminum. The top and
bottom covers are perforated allowing flow-through ventilation. All operating controls
and indicators are on the front panel, while all input and output cables are connected
to the rear panel (except for the phone jack).
The front panel is overlaid with a green bezel etched with control
markings. All pushbuttons are mounted on a printed circuit card positioned behind
the front panel, and extend through cutouts in the front panel. The remaining
controls and line audio/signal strength meter are mounted directly on the front
panel. The tuned frequency numeric display is mounted on a card positioned behind a
cutout in the front panel, over which a polarized filter is installed. The audio phones
jack, RF gain control and phone level controls are also mounted on the front panel.
The rear panel mounts all input, output, and accessories, except for the
phones jack. BNC connectors are supplied for the RF input, IF output and 1 MHz
reference input/output. The INT/EXT clock switch for selecting internal or external
timebase reference is located next to the 1 MHz reference input/output. Two circular
connectors supply an output for Line Audio and Phone Audio. The rectangular
fuseholder has the additional functions of line filter, voltage selection and ac line
cord receptacle. Also on the rear panel are two heat sinked regulators (+15 Vdc and
+5 Vdc), and the three circular connectors for remote control.
Loosening 34 quarter-turn fasteners allows the top cover to be removed
from the receiver exposing four main compartments. The four compartments are from
left to right as follows: power distribution and the input converter; IF modules;
digital control; and synthesizer. The use of separate compartments provides excellent
mechanical support and shielding.
Removing the bottom cover via 34 quarter-turn fasteners exposes four
motherboards that mount a total of 17 circuit cards and the components mounted on
the front panel. All connections to the motherboard are push-on plugs so replacement
of the motherboard consists of removing only 17 screws and the plugs.
1.3 EQUIPMENT SUPPLIED
The equipment supplied consists of the receiver and a detachable line cord.
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