Motorola Gp328 Gp338 Detailed 6804110j64 F Manual

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...

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....

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...

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...

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...

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...

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...

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...

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...