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Motorola Gp328 Gp338 Detailed 6804110j64 F Manual

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    							Transmitter6E-53.1.2 Antenna SwitchThe antenna switch circuit consists of two pin diodes (D100 and D101), a RF network (C147 and
    L103), and a DC feed network (L104, C144 and current limiting resistor R101). In the transmit mode,
    PCIC (U102) pin 32 goes high supplying current via the feed network to bias the diodes “on”. The
    shunt diode (D101) shorts out the receiver port and L103 is connected from the RF path to ground.
    L103 and the input capacitance of the lowpass filter form a parallel resonant circuit, effectively
    disconnecting the receiver port from the antenna while not loading the transmit path. In the receive
    mode, pin 32 goes low and the.the diodes are off. D100 looks like a high impedance disconnecting
    the transmitter from the antenna while L103 and C147 form a series resonant circuit to connect the
    receiver to the antenna.3.1.3 Harmonic FilterThe harmonic filter consists of components C103, C106, C107,C110, C111, C114, C115 and 3
    inductors which are a part of the SH100 assembly. The harmonic filter for lowband is pole zero design
    which give greater attenuation lower in frequency where the harmonic energy of the transmitter is the
    greatest and less attenuation high in frequency where there is less harmonic energy. The harmonic
    filter insertion loss is typically less than 0.8 dB3.1.4 Antenna Matching NetworkThe antenna matching network (T100) matches the antennas impedance with the harmonic filter to
    optimize the performance of the transmitter and receiver.3.1.5 Power Control Integrated Circuit (PCIC)The transmitter uses the PCIC (U102) to regulate the power output of the radio. To accomplish this,
    the voltage across R102 is sensed. This voltage drop is directly proportional to the current drawn in
    the final stage of the transmitter. This voltage is compared to a programmable reference inside the
    PCIC and the voltage on PCIC pin 4 adjusted. Pin 4 connects to the PA driver IC (U101) pin 1 via
    resistor R100 and varies RF output power of the driver. This controls the current drain of the final
    stage and sets the output power.3.1.6 Temperature Cut Back CircuitTemperature sensor VR101 and associated components are part of a temperature cut back circuit.
    This circuit senses the printed circuit board temperature around the transmitter circuits and outputs a
    DC voltage to the PCIC. If the DC voltage produced exceeds the set threshold of the PCIC, the
    transmitter output power decreases to reduce the transmitter temperature.                                                                                              
    						
    							6E-6Receiver4.0 Receiver4.1 Receiver Front-EndThe RF signal received by the antenna is routed through the transmitter lowpass filter and antenna
    switch. These circuits are described in the transmitter section.The signal next passes through a
    highpass filter consisting of L501, L502, C538, C533 and C504. This filter serves to reject below band
    signals and has a 3 dB corner frequency of 27 MHz.
    The output of the highpass filter is connected to an RF amp consisting of Q509 and associated
    biasing components. This is a BJT amplifier powered off 5 volts and has 13 dB of gain. The amplifier
    drives a lowpass filter consisting of L503, L504 L507, C534, C535, C536, C537 and C515. This filter
    is a pole zero design that filters off harmonic components from the RF amp. The 3 dB corner of this
    filter is at 56 MHz.
    The output of the lowpass filter is connected to the passive double balanced mixer consisting of
    components T501, T502, and D501. After mixing with the first local oscillator up-converted to a
    109.65 MHz IF signal.
    The IF signal coming out of the mixer is transferred to the crystal filter (FL301) through a resistor pad
    (R507, R508 and R509) and a diplexer (C516 and L508). Matching to the input of the crystal filter is
    provided by L301, L302, C301 and C302. The 3 pole crystal filter provides the necessary selectivity
    and intermodulation protection.Figure 6-2: Lowband Receiver Block DiagramDemodulator
    SynthesizerCrystal
    Filter Mixer Lowpass
    Filter RF Amp Highpass
    Filter Antenna
    Switch RF Antenna
    First LO
    from FGU
    Recovered Audio
    Squelch
    RSSI
    SPI Bus 17.0 MHz
    Reference Clock
    Second
    LO VCOJackLowpass
    FilterIF AmpAGC
    ProcessingIF IC
    U303                                                                                              
    						
    							Receiver6E-74.2 Receiver Back-EndThe output of crystal filter FL301 is connected to the input of IF amplifier transistor U301. Components
    L303 and C348 and R301 form the termination for the crystal filter and the signal is coupled to one
    gate of U301 by C303. The IF amplifier is a dual gate MOSFET powered off of the 5 volt supply. The
    first gate receives the IF signal as indicated previously. The second gate receives a DC voltage from
    U302 which serves as an AGC control signal. This signal reduces the gain of the IF amplifier to
    prevent overload of the IF IC, U303. The gain can be varied from a maximum of 13 dB to an
    attenuation of 55 dB. The output IF signal from U301 is coupled into U303 (pin 3) via C306, R304 and
    L304 which provides matching for the IF amplifier and U303.
    The IF signal applied to pin 3 of U303 is amplified, down-converted, filtered, and demodulated, to
    produce recovered audio at pin 27 of U303. This IF IC is electronically programmable, and the
    amount of filtering, which is dependent on the radio channel spacing, is controlled by the
    microprocessor. Additional filtering, once externally provided by the conventional ceramic filters, is
    replaced by internal filters in IF IC U303.
    The IF IC uses a type of direct conversion process, whereby the externally generated second LO
    frequency is divided by two in U303 so that it is very close to the first IF frequency. The IF IC (U303)
    synthesizes the second LO and phase-locks the VCO to track the first IF frequency. The second LO is
    designed to oscillate at twice the first IF frequency because of the divide-by-two function in the IF IC.
    In the absence of an IF signal, the VCO searches for a frequency, or its frequency will vary close to
    twice the IF frequency. When an IF signal is received, the VCO locks onto the IF signal. The second
    LO/VCO is a Colpitts oscillator built around transistor Q301. The VCO has a varactor diode, CR301,
    to adjust the VCO frequency. The control signal for the varactor is derived from a loop filter consisting
    of components C308, C309, and R310.
    The IF IC (U303) also performs several other functions. It provides a received signal-strength
    indicator (RSSI) and a squelch output. The RSSI voltage is also used to control the automatic gain
    control (AGC) circuit at the back end.
    The demodulated signal on pin 27 of U303 is also used for squelch control. The signal is routed to
    U404 (ASFIC) where squelch signal shaping and detection takes place. The demodulated audio
    signal is also routed to U404 for processing before going to the audio amplifier for amplification.4.3 Automatic Gain Control CircuitThe automatic gain control circuit provides automatic reduction of gain to prevent overloading of
    backend circuits. This is achieved by lowering the voltage on one gate of U301 which will reduce the
    drain current in that part and lower its gain.
    The Radio Signal Strength Indicator (RSS I) voltage signal for the IF IC (U303) is used to drive the
    AGC processing circuitry consisting of R306, R307, R308, R309 C307 and U302. As the received
    signal gets stronger, the RSSI line will rise. When the RSSI line passes a certain threshold, the
    voltage at the output of U302 will begin to drop. This voltage is connected to one gate of IF amplifier
    U301 through resistor R305. As this voltage decreases, it will lower the drain current in U301 and
    reduce the gain of the stage. This will limit the power incident on the IF IC, U303.                                                                                              
    						
    							6E-8Frequency Generation Circuitry5.0 Frequency Generation CircuitryThe frequency generation circuit, shown in Figure 6-3 , is composed of Low Voltage Fractional-N
    synthesizer U205 and discrete RX VCO, TX VCO.and buffers as well other supporting circuitry. The
    synthesizer block diagram illustrates the interconnect and support circuitry used in the region. Refer
    to the schematic for the reference designators.
    The synthesizer is powered by regulated 5V and 3.3V. The 5 volt signal to the synthesizer as well as
    the rest of the radio is provided by U204. The 3.3 v signal is provided from U400 in the controller. The
    5V signal goes to pins 13 and 30 while the 3.3V signal goes to pins 5, 20, 34 and 36 of U201. The
    synthesizer in turn generates a superfiltered 4.3V which powers the VCOs and buffers.
    In addition to the VCO, the synthesizer also interfaces with the logic and ASFIC circuitry.
    Programming for the synthesizer is accomplished through the data, clock and chip select lines (pins
    7, 8 and 9) from the microprocessor, U409. A 3.3V dc signal from pin 4 indicates to the
    microprocessor that the synthesizer is locked.
    Transmit modulation from the ASFIC is supplied to pin10 of U205. Internally the audio is digitized by
    the Fractional-N and applied to the loop divider to provide the low-port modulation. The audio runs
    through an internal attenuator for modulation balancing purposes before going out at pin 41 to the
    VCO.Figure 6-3: Lowband Frequency Generation Unit Block DiagramVoltage
    MultiplierSynthesizer
    U205Loop
    FilterTo
    Mixer
    To PA
    DriverVCPAux2
    Aux3
    MOD Out
    Modulating
    Signal Indmult
    17.0 MHz
    Ref. Osc.Switching
    NetworkVSFPrescalar inputTX VCO RX VCO
    Buffer                                                                                              
    						
    							Frequency Generation Circuitry6E-95.1 SynthesizerThe Fractional-N synthesizer, shown in Figure 6-4, uses a 17.0 MHz crystal (Y201) to provide a
    reference for the system. Along with being used in the LVFracN, the 17.0 MHz signal is provided at
    pin19ofU205forusebytheASFICandLVZIF.
    The LVFractN IC (U205) further divides this by 8 internally to give 2.125 MHz to be used as the
    reference frequency in the frequency synthesis. While UHF and VHF can use other references,
    (divide by 7 or divide by 7/8), only the divide by 8 function is valid for lowband.
    The internal oscillator device in the LVFracN together with C236, C237, C242, R219, CR211and Y201
    comprise the reference oscillator. This oscillator is temperature compensated is capable of 2.5 ppm
    stability over temperatures of -30 to 85°C. There is temperature compensation information that is
    unique to each crystal contained on Y201 that is programmed into the radio when built.
    The loop filter consists of components C256, C257, C259, R224, R225 and R228. This circuit
    provides the necessary dc steering voltage for the VCO and determines the amount of noise and spur
    passing through.
    To achieve fast locking for the synthesizer, an internal adapt charge pump provides higher current at
    pin 45 of U205 to put the synthesizer within lock range. The required frequency is then locked by
    normal mode charge pump at pin 43.
    Both the normal and adapt charge pumps get their supply from the inductive voltage multiplier made
    up of C240, C246, C247, C249, D201, and L223. This circuit provides 13.3V at pin 47 of U205.Figure 6-4: Lowband Synthesizer Block DiagramDATA
    CLK
    CEX
    MODIN
    VCC,DC5V
    XTAL1
    XTAL2
    WARP
    PREIN
    VCPREFERENCE
    OSCILLATORVOLTAGE
    MULTIPLIERVOLTAGE
    CONTROLLED
    OSCILLATORS2-POLE
    LOOP
    FILTERDATA (U409 PIN 100)
    CLOCK (U409 PIN 1)
    CSX (U409 PIN 2)
    MOD IN (U404 PIN 40)
    +5V (U204 PIN 4)7
    8
    9
    10
    13, 30
    23
    24
    25
    32
    47
    INDMULTBIAS1 SFOUTAUX3 AUX2 IADAPTIOUTGND FREFOUTLOCK4
    19
    6, 17, 22, 29, 31, 33, 44
    43
    45
    1
    2
    28
    1640FILTERED 4.3VSTEERING
    LINE LOCK (U409 PIN 56)
    PRESCALER INLO RF INJECTION
    TX RF INJECTION
    (FIRST STAGE OF PA) FREF (U303 PIN 21 & U404 PIN 34)39 BIAS241SWITCHING
    NETWORK 5, 20, 34, 36
    (U400 PIN 1) VDD,3.3VMODOUT U205
    LOW VOLTAGE
    FRACTIONAL-N
    SYNTHESIZER                                                                                              
    						
    							6E-10Frequency Generation Circuitry5.2 VCO - Voltage Controlled Oscillator
    5.2.1 Receive VCOThe receive VCO is a Colpitts type design and using two active devices in parallel, Q202 and Q204.
    The oscillator is powered off of the 4.3 volt super filter supply when the AUX3 line goes low. The
    oscillator operates from 139 to 160 MHz, and the frequency is tuned by varactor diodes CR201 and
    CR202.5.2.2 Transmit VCOThe transmit VCO is a Hartley type design with active devices Q203. The oscillator is powered off of
    the 4.3 volt super filter supply when the AUX2 line goes low. The oscillator operates from 29.7 to 42
    MHz for Range 1 and 35 to 50 MHz for Range 2. The frequency is tuned by varactor diodes in U203.
    Note that the values of the inductive tap, L208 and L209, and the capacitor C215 which couples the
    varactor to the oscillator tank vary between the ranges.5.2.3 BufferBoth the receive and transmit VCO are fed to a buffer amplifier Q201. This is a BJT amplifier that
    boosts the signal levels to +4 dBm and provides reverse isolation to the oscillators. The amplifier is
    powered off the 4.3 volt super filter supply and the feed network is combined with the transmit filter.5.2.4 Diplexer and Output FiltersThe output of the buffer drives a pair of parallel filters. One filter is a lowpass filter in the TX pass that
    passes 29.7 - 50 MHz signals for the transmitter into the power amplifier while rejecting the receive
    LO injection signals at 139 - 160 MHz. This filter is comprised of L204, L211, L212, C230 and C231.
    The other filter is a highpass filter which passes 139 - 160 MHz signals for the receive LO into the
    mixer while rejecting the transmit injection signals at 29.7 -50 MHz. This filter is comprised of
    C228,C229,C235 and L215.5.2.5 Prescalar FeedbackThe prescalar input signal for receive and transmit is tapped off of the outputs of each filter by
    resistors R234 and R238. This signal is routed to U205 pin 32. After frequency comparison in the
    synthesizer, current is transferred in the loop filter and a control voltage is generated at the output of
    the loop filter to adjust the frequency of the VCO. This voltage is a DC voltage between 3.5V and 9.5V
    when the PLL is locked on frequency.                                                                                              
    						
    							Notes For All Schematics and Circuit Boards 6E-116.0 Notes For All Schematics and Circuit Boards* Component is frequency sensitive. Refer to the Electrical Parts List for value and usage.
    1.Unless otherwise stated, resistances are in Ohms (k = 1000), and capacitances are in picofarads
    (pF) or microfarads (µF).
    2.DC voltages are measured from point indicated to chassis ground using a Motorola DC multime-
    ter or equivalent. Transmitter measurements should be made with a 1.2 µH choke in series with
    the voltage probe to prevent circuit loading.
    3.Reference Designators are assigned in the following manner:
    100 Series = Transmitter
    200 Series = Frequency Generation
    300 Series = Receiver
    400/500 Series = Controller
    600 Series = Keypad Board
    4.Interconnect Tie Point Legend:
    UNSWB+ = Unswitch Battery Voltage (7.5V)
    SWB+ = Switch Battery Voltage (7.5V)
    R5 = Receiver Five Volts
    CLK = Clock
    Vdda = Regulated 3.3 Volts (for analog)
    Vddd = Regulated 3.3 Volts (for digital)
    CSX = Chip Select Line (not for LVZIF)
    SYN = Synthesizer
    DACRX = Digital to Analog Voltage (For Receiver Front End Filter)
    VSF = Voltage Super Filtered (5 volts)
    VR = Voltage Regulator
    6-LAYER CIRCUIT BOARD DETAIL VIEWING
    COPPER STEPS IN PROPER LAYER SEQUENCELAYER 1 (L1)
    LAYER 2 (L2)
    LAYER 3 (L3)
    LAYER 4 (L4)
    LAYER 5 (L5)
    LAYER 6 (L6)INNER LAYERS SIDE 1
    SIDE 2                                                                                              
    						
    							6E-12 Notes For All Schematics and Circuit Boards                                                                                              
    						
    							Circuit Board/Schematic Diagrams and Parts List6E-137.0 Circuit Board/Schematic Diagrams and Parts List
    B503B504
    C103
    C106
    C107
    C110 C111
    C114C115C118C119
    C120 C121C122
    C123
    C130C136
    C144
    C145C147 C148
    C149
    C201C202C203C206
    C218
    C219C220
    C223
    C224
    C228
    C229
    C232C233
    C234
    C235C237
    C247 C249C260
    C263
    C283
    C284C285 C286
    C287
    C301C302
    C303
    C304
    C305
    C306
    C308 C309
    C310
    C311
    C312
    C313C314
    C315C316
    C317C348
    C400
    C401
    C402
    C403
    C404
    C406C423
    C424 C425 C426
    C427C428C429
    C432 C438
    C440
    C441 C443
    C444
    C467 C471 C472 C473
    C480C482
    C490
    C491
    C492 C493C494 C495C496C497
    C500
    C502
    C505 C511C512C513
    C514
    C515
    C516
    C522
    C534 C535 C536
    C537
    CR201
    CR202CR211
    CR301
    CR412
    CR413
    CR440
    CR502
    4 3
    2 CR503
    D100
    D101 D210
    D211
    D501 E407
    E408
    E409
    5
    64 3
    2
    1
    FL301
    1
    40
    J40022201 21J403
    L100 L101
    L102
    L103
    L104
    L105
    L106
    L107
    L110
    L201
    L202 L203L210 L226L301
    L302
    L303
    L304L306L308
    L400L401
    L503
    L504L507 L508PB501 PB502 PB503
    PB504
    PB505
    12
    3Q100
    Q201Q202
    Q204
    Q288
    Q301 Q400
    Q403
    43
    Q405 4
    3 Q411
    4
    3
    Q417
    Q510 R104
    R105
    R106
    R112 R203
    R227
    R229 R230R233R235
    R237
    R285
    R286R287
    R288R289
    R301
    R302
    R303
    R304R305
    R310
    R312R314
    R315
    R316
    R317
    R401
    R402
    R403R405
    R406 R407R408 R410R416R418 R421R427R428
    R429
    R435
    R436 R437
    R446
    R447
    R448
    R450
    R476
    R477R478
    R481
    R492
    R499R501
    R502
    R507
    R508 R509
    R510
    R514
    R515
    RT400
    SH100 SH200
    SH203SH301 SH302 SH303 SH400
    SH401SH501 SH502
    2 1 54
    3
    T100
    64
    3T501
    64
    3T502
    TP201
    TP401
    TP402
    TP405TP406 TP410
    TP415TP500TR201
    1
    168 9
    U101 U204
    U301
    4
    58
    U400
    2221
    8
    7
    1
    U405
    32
    17
    16 1
    U406
    VIEWED FROM SIDE 1
    1 4
    5
    8
    U407
    VR102
    VR434VR447VR449
    VR450VR500
    VR501 VR502
    64 3 1
    Y201
    FL0830474O
    Lowband 29-42/35-50MHz Main Board Top Side PCB No. 8486291A02
     http://www.myradio168.name 
    						
    							6E-14Circuit Board/Schematic Diagrams and Parts List
    C108
    C117
    C124 C125
    C126
    C127
    C128
    C129
    C131 C132
    C133
    C134
    C135 C137
    C138
    C139 C140
    C141C142
    C143C146
    C204
    C205
    C214 C215
    C216
    C221
    C222
    C225 C226 C227
    C230
    C231
    C236C242
    C255
    C256
    C257
    C258C259C261C280 C281C297
    C298
    C299
    C307 C319
    C320 C321
    C323 C324
    C325
    C326 C327 C328 C330 C331 C332
    C333
    C334
    C335
    C336C337
    C339
    C340
    C341
    C342C343
    C405
    C407
    C408
    C409
    C410
    C411
    C412
    C414
    C415
    C416
    C419
    C420
    C421
    C422
    C430 C431
    C433C434
    C435C436
    C437
    C442
    C445
    C447C448
    C449
    C450
    C451
    C452
    C453
    C456
    C458
    C459C463C466
    C475
    C476 C479
    C481 C503
    C504
    C506
    C507
    C533
    C538
    CR200
    CR203 CR204
    CR411
    D502
    E100E400
    E401
    E402
    E403
    E404E405
    E406
    F13
    FL401
    3 2 1
    J1
    1
    2 3 4
    J1014
    J102
    L108
    L109
    L200
    L204
    L207
    L208 L209
    L211 L212L215
    L225 L305L307
    L410
    L411
    L501L502
    M100
    M101
    M202 M300M301
    M400
    M401 Q203
    43
    Q410
    Q416
    Q509
    R101
    R102
    R103
    R107R108
    R109
    R110 R111
    R113 R114
    R115 R116
    R117
    R118R119
    R204
    R206R219
    R222 R223
    R224
    R225
    R228
    R231
    R232 R234R236
    R238R239
    R306R307R308 R309 R318
    R400R409
    R411 R413R414
    R415
    R419
    R420
    R423
    R424 R425
    R426
    R431
    R432
    R434R445 R449
    R457 R460
    R461R462R463
    R471 R472
    R473
    R475 R503
    R504
    R505
    R512
    R513
    2 C8
    C
    4
    S501
    4
    5
    32
    S502
    VIEWED FROM SIDE 2
    SH201
    SH202 SH300
    SH402
    SH403 SH500
    TP100 TP200
    1
    17
    925
    U102U200
    5 8
    1
    4
    U203
    13
    1224 25
    3736
    48
    1
    U205
    U207
    U302
    13
    12 24
    25
    37 36
    481
    U303
    13
    1224 25
    3736
    48
    1
    U404
    1
    76 5126
    U409
    U410
    11
    1 20
    10
    U420
    VR101
    VR200VR201
    VR202
    VR203
    VR432
    VR433
    VR445
    VR446
    VR448FL0830475O
    Lowband 29-42/35-50MHz Main Board Bottom Side PCB No. 8486291A02
     http://www.myradio168.name 
    						
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