Electrical Characteristics; Tuning Encoder; Front Panel Switch/Encode Assembly; Section I - Watkins-Johnson Company WJ-8718A/MFP Instruction Supplement

WJ-8718A/MFP
SECTION I
GENERAL DESCRIPTION
GENERAL DESCRIPTION
1.1
ELECTRICAL CHARACTERISTICS
The WJ-8718A/MFP (Microprocessor Front Panel) Option
(Figure 1-1)
allows local
digital control of all receiver parameters while providing push-button access to 100
programmable memory channels. Optional remote control, utilizing the EIA Standard RS-232/C
format or the IEEE Standard 488-1975 format, can be accomplished by installing a 232M or
488M I/O Interface.
Standard local control of a WJ-8718A/MFP Option equipped receiver is enhanced
by the use of momentary-contact, push-button switches, with LED indicators. Selection of RF
and BFO frequencies is achieved by a keypad or tuning wheel. RF frequency from 5 kHz to
29.99999 MHz is displayed in megahertz to a 10 Hz resolution; BFO frequency between -8 and
+8 kHz is displayed in kilohertz to a 10 Hz resolution. The 7-segment LED displays are
available in a choice of three colors: yellow, red, or green.
Ninety-nine discrete (and one implicitly addressed) programmable memory channels
allow for the selection of a method of receiver control to suit specific needs. Memory channels
can be loaded with receiver parameter data and accessed one at a time or scanned sequentially.
Automatic scan of a group of memory channels (with pre-selected start and stop addresses)
tunes the receiver sequentially to the stored parameters.
The front panel functions are implemented through an 8-bit microprocessor, and
the address, storage, and memory devices required to interface the front panel components with
the signal processing circuits in the receiver. The interface circuits and the front panel
components form the two key functional sections of the MFP Option.
1.1.1 TUNING ENCODER
The Tuning Encoder (MFP- A2) converts the rotation of the front panel tuning
wheel into digital pulse trains which are monitored by the microprocessor through a logic
circuit on the FrontPanel Encode Board (MFP-A1A1).
1.1.2 FRONT PANEL SWITCH/ENCODE ASSEMBLY
The Front Panel Switch/Encode Assembly (MFP-Al) consists of a Type 7960"56-1
Front Panel Encode Board (MFP-AIAl), a Type 794309-X Front Panel Switchboard
(MFP-A1A2), interconnecting track, and amplifiers for the headphone audios.
With the exception of the power switch, the switchboard contains all front panel
switches, LED indicators, and LED display arrays. Logic circuits on the Front Panel Encode
Board interface the switchboard with the microprocessor system. The front panel assembly is
functionally dependent on the Type 794275-X and Type 794308-2 Interface Boards, which form
the second functional section of the MFP Option. Multiconductor cables interconnect the f--ront
panel assembly to the interface boards.
1-1