Watkins-Johnson Company WJ-8718-19/FE Instruction Manual page 91

CIRCUIT DESCRIPTION WJ-8718-19/FE HF RECEIVER
3.2.6.2 Input/Output Signal Interfaces
The following input/output signals interface with the Digital Control
Section: J
a. Front Panel Control/Display Data - Front panel bandwidth,
mode, gain and frequency data is received from the front panel!
Also, receiver tuned frequency data and signal strength/line
audio status data is sent to the front panel for display.
b. Tuning Data - BCD encoded data words are sent from the
Digital Control Section to program the output frequencies of
the 1st, 2nd, 3rd and BFO synthesizers.
c. BW Select - A 5-bit BW select data word is sent to the
IF/Demodulator Section to select each -of the five 3rd IF
filters.
d. Mode Select - A 5-bit mode select data word is sent to the
IF/Demodulator Section to select AM, FM or CW/SSB modes.
e. Gain Select - A 2-bit mode select data word is sent to the
IF/Demodulator Section select SLOW, FST or MAN gain modes.
In MAN mode, a MAN GAIN analog control voltage is sent to
the IF/Demodulator Section to vary the gain of the 3rd IF
amplifier.
f. RF Gain Control - This dc voltage is supplied to the RF/IF
Conversion Section. This level is nominally 0 Vdc under
normal signal conditions, increasing to -4 Vdc under maximum;
signal conditions.
g. Status - Two dc outputs are received from the IF/Demodulator
Section and represent the relative signal strength and line
audio output level.
h. Combined Audio - This low level audio is received from the
IF/Demodulator Section for distribution to the front panel
headphone amplifier.
3.2.7 POWER SUPPLY SECTION
The Power Supply Section received 115 or 230 Vac input from the AC line
and converts it to dc levels required by the receiver circuits. There are two main
groups of regulator assemblies: three are mounted on the main chassis, three are
mounted on the Synthesizer Motherboard, A5.
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