WJ-8640-1 and the AN/PRD-11

The WJ-8640-1 Man pack Receivers a rugged portable unit designed to operate under extreme environmental conditions, and receive AM, FM and CW emissions l Sideband filters are employed when receiving SSB/CW signals in the 0.5-30 MHz and 20-80 MHz range. The Receiver, has a LED counter w/DAFC, 10 D cell or BA-4386 detachable battery pack or vehicular supply, 4.2"h X 11.4"w X 11.7"d, 18lbs, (mil AN/GRR-8V plug-in 10/50/200kHz AM/FM/CW/USB/LSB, port-0.5-500MHz 5/20kHz optional.

The use of the WJ-9120, WJ-9121 or the WJ-9124 Tuning Head enables the Receiver to cover the frequency range of 0.5-30 MHz, 20-250 MHz or 250-500 MHz respectively. Located on the Receiver’s front panel is the BAND (MHz) selector switch. The Receiver employs a built-in frequency counter with a six digit display and tuned frequency readout within a resolution of 1 kHz. The counter includes Digital Automatic Frequency Control (DAFC) circuitry, whose operation locks the tuned frequency to within 1 kHz, over the entire tuning range. The Counter display switch, located on the front panel, does not permit DAFC operation when the COUNTER OFF position is used. With the DISPLAY OFF mode chosen the DAFC will continue to operate. The controls associated with the counter are the COUNTER OFF-DISPLAY INTENSITY switch and the DAFC LOCK-OFF switch. These tuning assemblies are interchangeable drop-in units requiring simple hand tools for installation and removal. The receiver employs three standard IF bandwidth filters of 10, 50 and 200 kHz. These bandwidths are front panel selectable.

N/PRD-11 Direction Finding Setup.

The WJ-8975A Direction Finder is designed to be used in conjunction with the Watkins-Johnson Company’s Man portable/Vehicular Direction Finding System. This system includes the WJ-8640 Series Man pack Receiver, the WJ-9180 Series Signal Monitor, and the WJ-9880 Series Antenna.

The WJ-8975A Direction Finder is the central controlling unit in the DF System. As the central controlling unit in the DF System, the WJ-8975A Direction Finder controls the element switching network at the antenna. The Direction Finder also processes the signals obtained from the WJ-8640 Series Receiver’s Signal Monitor Output. An accurate bearing of the incoming signal provided by the WJ-8640 Series Receiver is displayed with an easy to read, 3 digit LED display. This 3 digit display reads in lo increments. Surrounding the 3 digit LED display is a circular array of 60 LED's that simulates a compass. The LED’s compass type display is an additional bearing indicator which supports the primary 3 digit LED display.

The complete Man portable/Vehicular Direction Finding System has been ruggedized to provide dependable service for field applications. The WJ-8975A Direction Finder, WJ-8640 Series Man pack Receiver, and WJ-9180 Series Portable Signal Monitor have rubber feet on the bottom of their cases to enable stacking the equipment in the field. For vehicular use, a WJ-8640/MT (mounting tray) will have to reutilized for each unit. The WJ-8640/MT (mounting tray) provides a means of securing the Direction Finding System to the vehicle. All controls and connectors needed for field operation of the Direction Finding System are located on the equipment front panels. Refer to Section II for details of operation which pertain to the WJ-8975A. For vehicular operation, one can utilize the vehicle's power supply to energize the WJ-8975A.

The WJ-8975A Direction Finder was designed to be used in conjunction with the following units which makeup the Man portable/Vehicular direction Finding System: WJ-8640 Series Man pack Receiver, WJ-9180 Series Portable Signal Monitor (optional) WJ-9880 ADF Antenna

Building a Battery Box.

As the Pan adapter did not have a battery compartment, I manufactured one from steel until I can find an original.