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FREQUENCY SYNTHESIZER
The frequency synthesizer consists of a microcomputer,
electrically erasable PROM(S) (EEPROM), a frequency
synthesizer IC, transmit and receive VCO’s, and associated
circuitry. The frequency synthesizer under control of the mi-
crocomputer generates all transmit and receive RF frequen-
cies.
EFEPROM
The EEPROM stores binary data for all RF frequencies,
Channel Guard tones/ digital codes, and the timing function
of the carrier control timer (CCT). The microcomputer ac-
cesses the EEPROMS and provides the correct WALSH bits
to the Channel Guard board to generate the correct Channel
Guard tone or digital code on a per channel basis.
PROGRAMMING
The EEPROM allows the radio to be reprogrammed as
needed to adapt to changing system requirements. RF fre-
quencies, Channel Guard tones and digital codes, and the
CCT function can be reprogrammed.
Depending on the configuration of the radio, one or two
EEPROMS may be provided. Radios not equipped with a
MODE A/B switch will have one EEPROM. Radios with
more than 16 channels and those with the MODE switch
will have two EEPROMS.
The EEPROMS can be reprogrammed through the radio
front connector using the General Electric Universal PROM
Programmer Model TQ23IO. This programmer allows all
information to be loaded simultaneously.
Alternatively, a single channel Programmer Model
4EX22A10 allows the user to reprogram the radio on a per
channel basis. This programmer requires the removal of the
radio top cover and any option boards present. A special
programming jack, J711, is provided in the radio for inter-
connections.
Programming instructions are provided in the respective
Programmer Maintenance Manuals.
TRANSMITTER
The transmitter consists of the exciter, frequency synthe-
sizer, TX VCO, and a power amplifier assembly. The PA as-
sembly consists of a PA board mounted along the side of the
radio next to the heat sink assembly. The PA board also con-
tains a hermetically sealed antenna relay and a low pass fil-
ter.
RECEIVER
The receiver consists of the frequency synthesizer, RX
VCO, injection amplifiers, front end, IF and limiter detector.
In UHS receivers, a preamplifier board is added in the re-
ceiver front end. Audio and squelch circuitry for the re-
ceiver is located in the system section of the TRS board.
Jacks for the Channel Guard and other structured options
are also located in the system area.
CONTROL UNITS
Several "S" series control units are available for use with
the DELTA-SX, radio combinations.
The S-500 control unit contains an on-off volume con-
trol switch, a rotary channel selector switch for 1, 8, or 16
channels, a MODE A/B switch (optional) to expand the
channel select capability to 32, seven segment channel indi-
cators(s), a red transmit indicator, channel busy indicator
(optional), and an external tone option jack. Options that
may be used with this control unit include Type 90 and 99
tone, squelch operated relay SOR, GE-STAR encoder, and
public address.
The S-600 control unit contains an on-off volume con-
trol switch, squelch disable switch, red transmit indicator,
and a 7 segment channel indicator. A rotary channel select
switch permits selection of up to eight- channels. A white
power on indicator is used for back lighting the front panel.
Space is provided for two optional. pushbutton switches and
two optional indicators.
The S-900 series control units designed specific-ally for
the DELTA class radios are highly versatile, software con-
trolled units providing numerous functions and options in-
cluding:
• Dual priority Scan
• Digita1 Volume Control
• Digital Squelch Control
• Type 90 or 99 Encode Tones
• GE-STAR Identification
When programming, remember that all RF frequen-
cies must be divisable by 5 or 6.25 kHz but not both.
NOTE
LBI-31564
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