Motorola Gp328 Gp338 Detailed 6804110j64 F Manual
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Receiver6D-74.3 Automatic Gain Control Circuit(Refer to330-400MHz Receiver Front End Schematic Diagramon page 6D-16) The front end automatic gain control circuit is to provide automatic gain reduction of the front end RF amplifier via feedback. This action is necessary to prevent overloading of backend circuits. This is achieved by drawing some of the output power from the RF amplifier’s output. At high radio frequencies, capacitor C331 provides the low impedance path to ground for this purpose. CR308 is a PIN diode used for switching the path on or off. A certain amount of forward biasing current is needed to turn the PIN diode on. Transistors Q315 provides this current where upon saturation, current will flow via R347, PIN diode, collector and emitter of Q315 and R319 before going to ground. Q315 is an NPN transistor used for switching here. Maximum current flowing through the PIN is mainly limited by the resistor R319. Radio signal strength indicator, RSSI, a voltage signal, is used to drive Q315 to saturation hence turning it on. RSSI is produced by U301 and is proportional to the gain of the RF amplifier and the input RF signal power to the radio. Resistor network at the input to the base of Q315 is scaled to turn on Q315, hence activating the AGC, at certain RSSI levels. In order to turn on Q315, the voltage across the transistor’s base to ground must be greater or equal to the voltage across R319, plus the base-emitter voltage (Vbe) present at Q315. The resistor network with thermistor RT300 is capable of providing temperature compensation to the AGC circuit, as RSSI generated by U301 is lower at cold temperatures compared to normal operation at room temperature. Resistor R300 and capacitor C397 form an R-C network used to dampen any transient instability while the AGC is turning on.
6D-8Frequency Generation Circuitry5.0 Frequency Generation CircuitryThe Frequency Generation Circuitry is composed of two main ICs, the Fractional-N synthesizer (U201), and the VCO/Buffer IC (U241). Designed in conjunction to maximize compatibility, the two ICs provide many of the functions that normally would require additional circuitry. The synthesizer block diagram illustrates the interconnect and support circuitry used in the region. Refer to the relevant schematics for the reference designators. The synthesizer is powered by regulated 5V and 3.3V which come from U247 and U248 respectively. The synthesizer in turn generates a superfiltered 4.5V which powers U241. In addition to the VCO, the synthesizer must interface with the logic and ASFIC circuitry. Programming for the synthesizer is accomplished through the data , clock and chip select lines from the microprocessor. A 3.3V dc signal from synthesizer lock detect line indicates to the microprocessor that the synthesizer is locked. Transmit modulation from the ASFIC is supplied to pin10 of U201. 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 to the VCO.Figure 6-3: Frequency Generation Unit Block DiagramVol tag e MultiplierSynthesizer U201Dual Tran- sistorLoop FilterVCOBIC U241Low Pass FilterMatching NetworkAttenuatorTo Mixer To PA DriverVCPVmult1Aux3 Aux4 MOD Out Modulating Signal Vmult2Rx VCO Circuit Tx VCO CircuitTRB 16.8 MHz Ref. Osc.Rx Out Tx Out
Frequency Generation Circuitry6D-95.1 Synthesizer(Refer to330-400MHz Synthesizer Schematic Diagramon page 6D-18) The Fractional-N Synthesizer uses a 16.8MHz crystal (FL201) to provide a reference for the system. The LVFractN IC (U201) further divides this to 2.1MHz, 2.225MHz, and 2.4MHz as reference frequencies. Together with C206, C207, C208, R204 and CR203 , they build up the reference oscillator which is capable of 2.5ppm stability over temperatures of -30 to 85°C. It also provides 16.8MHz at pin 19 of U201 to be used by ASFIC and LVZIF. The loop filter which consist of C231, C232, C233, R231, R232 and R233 provides the necessary dc steering voltage for the VCO and determines the amount of noise and spur passing through . In achieving fast locking for the synthesizer, an internal adapt charge pump provides higher current at pin 45 of U201 to put synthesizer within the 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 capacitive voltage multiplier which is made up of C258, C259, C228, triple diode CR201 and level shifters U210 and U211. Two 3.3V square waves ( 180 deg out of phase) are first shifted to 5V, then along with regulated 5V , put through arrays of diodes and capacitors to build up 13.3V at pin 47 of U201. Figure 6-4Synthesizer Block DiagramDATA CLK CEX MODIN VCC,DC5V XTAL1 XTAL2 WARP PREIN VCPREFERENCE OSCILLATORVOLTAGE MULTIPLIERVOLTAGE CONTROLLED OSCILLATOR2-POLE LOOP FILTERDATA (U409 PIN 100) CLOCK (U409 PIN 1) CSX (U409 PIN 2) MOD IN (U404 PIN 40) +5V (U247 PIN 4)7 8 9 10 13, 30 23 24 25 32 47 VMULT2 VMULT1BIAS1 SFOUTAUX3 AUX4 IADAPTIOUTGND FREFOUTLOCK4 19 6, 22, 23, 24 43 45 3 2 28 14 1540FILTERED 5VSTEERING LINE LOCK (U409 PIN 56) PRESCALER INLO RF INJECTION TX RF INJECTION (1ST STAGE OF PA) FREF (U201 PIN 21 & U404 PIN 34)39 BIAS241DUAL TRANSISDUAL TRANSIS-485VR5 5, 20, 34, 36 (U248 PIN 5) AUX1 VDD,3.3VMODOUT U251 LOW VOLTAGE FRACTIONAL-N SYNTHESIZERTORSTORS
6D-10Frequency Generation Circuitry5.2 VCO - Voltage Controlled Oscillator(Refer to330-400MHz Voltage Controlled Oscillator Schematic Diagramon page 6D-19) Figure 6-5VCO Block Diagram The VCOBIC (U241) in conjunction with the Fractional-N synthesizer (U201) generates RF in both the receive and the transmit modes of operation. The TRB line (U241 pin 19) determines which oscillator and buffer will be enabled. A sample of the RF signal from the enabled oscillator is routed from U241 pin 12, through a low pass filter, to the prescaler input (U201 pin 32). After frequency comparison in the synthesizer, a resultant CONTROL VOLTAGE is received at the VCO. This voltage is a DC voltage between 3.5V and 9.5V when the PLL is locked on frequency.Presc RX TXMatching NetworkLow Pass Filter Attenuator Pin8 Pin14 Pin10 Level Shifter Network5V (U201 Pin28) VCC Buffers TX RF Injection U201 Pin 32AUX4 (U201 Pin3)AUX3 (U201 Pin2) Prescaler Out Pin 12 Pin 19 Pin 20TX/RX/BS Switching Network U241 VCOBIC Rx Active Bias Tx Active Bias Pin2 Rx-I adjustPin1 Tx-I adjustPins 9,11,17 Pin18Vsens Circuit Pin15Pin16 RX VCO Circuit TX VCO Circuit RX Tank TX TankPin7 Vcc-Superfilter Collector/RF in Pin4 Pin5 Pin6RX TX(U201 Pin28)Rx-SW Tx-SW Vcc-Logic (U201 Pin28) Ste er Line Volta ge (VCTRL)Pin13 Pin3TRB_IN LO RF INJECTIONVSFVSF VSF
Frequency Generation Circuitry6D-11The VCOBIC(U241) is operated at 4.54 V (VSF) and Fractional-N synthesizer (U201) at 3.3V. This difference in operating voltage requires a level shifter consisting of Q260 and Q261 on the TRB line. The operation logic is shown in Table 6-1. In the receive mode, U241 pin 19 is low or grounded. This activates the receive VCO by enabling the receive oscillator and the receive buffer of U241. The RF signal at U241 pin 8 is run through a matching network. The resulting RF signal is the LO RF INJECTION and it is applied to the mixer at T302 (refer to330-400MHz Receiver Front End Schematic Diagramon page 6D-16). During the transmit condition, when PTT is depressed, five volts is applied to U241 pin 19. This activates the transmit VCO by enabling the transmit oscillator and the transmit buffer of U241. The RF signal at U241 pin 10 is injected into the input of the PA module (U101 pin16). This RF signal is the TX RF INJECTION. Also in transmit mode, the audio signal to be frequency modulated onto the carrier is received through the U201 pin 41. When a high impedance is applied to U241 pin19, the VCO is operating in BATTERY SAVER mode. In this case, both the receive and transmit oscillators as well as the receive transmit and prescaler buffer are turned off.Table 6-1: Level Shifter LogicDesired ModeAUX 4 AUX 3 TRBTxLowHigh (@3.2V)High (@4.8V) Rx High Low LowBattery SaverLowLowHi-Z/Float (@2.5V)
6D-12 Notes For All Schematics and Circuit Boards6.0 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
Circuit Board/Schematic Diagrams and Parts List6D-137.0 Circuit Board/Schematic Diagrams and Parts List E409E407R410 R418 R437 32 17 U406 1 16 1 7 22 821 U405 J4001 40C426 C425E408 C423 TP401 TP402 TP410R435 C443C444RT400 C427 C428 8 54 1 U407L401 VR447 C429 C424 R428 R429 R492SH400R478 R408 21 1 J403 20 22 VR450 TP405 R421 L400 VR434 TP406TP415D403R450Q417 3 4 R477 C441 C490 C491 C492C493 C494 C495 C496C497C471 C473 C472VR449 Q403 Q400 Q405 3 4 R401 R402 R403R405 R407 R416 R446 R448 R476R481R406 R447 R427 SH401 U400 8 5 4 D401 CR440 C401 C402C400C467 C482 C403 C480 PB502 PB503 C216 C432 FL201 1 3 4 6 TP201 B503B504 C257C292 C228 C229 CR201 C212 C210 TP202 TP302 C238 Q210 3 4 Q260 3 4 R256R255 R206SH201 L232 L201 L202L203U247 C211C213C214C220 C230 C260 C294 C297 C233 C203 C217 C235 C291 C282 C283 SH241 C251 C253C289Q261 3 4 R260 R248 C247 C248 L282C273 3 L2431R243C286 R253 C285 C272 R339 C370 C386 R333L271 L273 L321 C374 C276C271 3 L2531Q241PB504 R351 R352 FL301SH323 L311C325 C324 C323R300 VR444 Q315 Q316 R316 R318R325 RT300 RT301 R338 R327 R319R326 R334 R335 R314 VR300 C328C397C391 CR308 T301 34 6 T3023 4 6 R309 R308R310 R348 SH303L310 L309 C375 C320C319 C322 C381 32 Q110 1 R107 R108 L160 C121 C160 C120 U101 9 8 161 R161 C161 C169 L113 C112L108 R120 R171 R173 R193 R104 R174 R106 SH101 L115 L117 L106 L114L107 L109 C118 C125C165 C113 C127 C110C114 C119 C122 C166C171 C131 C193 C117 C 111 C181 C115 C109 C116 C129 C180 PB501 VR440 C521 C502 VR501 Q505R506 R505 R507 C505 C512 C513 Q502 R502 SH321 CR310 Q320 R345R320 R355R322 R346 R321 R324L325 L332 C350 C362 C364C352 C351 C349 C354C363 C353 C384 C385 R342 R301R302 SH301 L301 L302 CR301 CR302C308C304 C301 C303 C302C305 CR503 2 34 R501 C520 VR443 C511 C514 PB505C331 L116 C141C140 SH100 L101 L102 L104 L105CR101 CR102 C102C104 C103 C106C107C188 C101 R317 R336 C333C396 ZMY0130348-O 330-400MHz Main Board Top Side PCB No. 8485726Z01 http://www.myradio168.name
6D-14Circuit Board/Schematic Diagrams and Parts List 2 S502 35 44 C 8 C S501 2 1 J101 4 3 2 J102 Q 111 3 4R101 R170M100 CR103 P100C108 R172 R133 H101 CR105 C172 C132 C173 R102 R131 R130 R132R109 L112 25 9 17 U102 1C133 C105 C130 C138C151 C170 C174 C134 C128 C135 C150 C152C126Q301 R304R340 R305R328 R306 R307 R303 R347 SH302 L340 L304 L306 L307 L303 L305 CR304 CR305CR303 C309 C315 C321 C395C307C310 C314 C380 C312 C318 C316 C313C317 C306 C311 R344R350 R343 M301 SH322 L331 L314 13 25 37 1U301 C337 C383 C390 C334 C356 C329 C336 C344 C345 C346 C347 C348 C360 C339 C340 C341 C342 C355 C361 C343 C357C382 C358C359 Q302 R315R313R311 R312M101 L330 B501 321 C327 C338C326 C330 R205 L505 U248 VR441 VR442 VR506 C277C522 C278 C279 C215 R329 F501 E101SH304 CR501 VR439 CR306C503 C123 Q310 R 111 R241 R252 R251 R242 R245R244 R349R331 R330 R332R110 R112 R254 M300SH242 L241 L242 L281 L251 U241 10 201 11 CR242 CR243 CR241 CR251 CR252C241 C246 C255 C281 C295 C372C252 C256 C244 C243 C245 C254C242C250 C371 C373 C378 R204 R231 R232R201 R233 R202 R281 SH202 L261 U210 3 4 U211 3 4 13 25 37 1U201CR203 C201 C264 C202 C218 C223 C224 C231 C296C298C234 C207 C206 C258 C259 C219C204C293 C232C263C208 C265 Y2014 3 2 C523 Q416 R409 R411R457 R462 R461 R432R463 R414 R415 R460R426 R420 R4193 FL401 E400E401E402E403E404E405 E406 M400 SH402L410 L411 U410 U409 26 51 76 1D402C431 C449 C453 C456C458 C459C463C466 C434 C435 C433C436 C437 Q410 3 4 R400 R413 R436 R475R434 R425R445 R449 R424 R472 R423 R431 R471 M401 SH403U420 10 20 111 13 25 37 1U404 C408C447 C451C409 C411 C414 C422 C450 C420 C415C407 C410 C416C421 C430 C448 C479 C481 C476 C440 C452C419 C475 R473 VR432 VR433 VR445 VR446 VR448 C445 C442 ZMY0130347-O 330-400MHz Main Board Bottom Side PCB No. 8485726Z01 http://www.myradio168.name
Circuit Board/Schematic Diagrams and Parts List6D-15 DEMOD LVZIF_SEL RSSI 16.8MHzCLK DACRx DATA Vdda Vdda RX_IN RX_INJR5 RECEIVER DATA CLK DACRX DEMOD RSSI LVZIF_SEL 16.8MHz RX_INJSWB+ TX_INJ Vdda FGU 16.8MHz 4V_3.3V 5V CLK CSX DATA LOCK MODIN R5 CSX 4V_3.3VSWB+ LOCK MODIN 5V DATA RESET RX_IN TX_INJ UNSWB+ TRANSMITTER 5V CLK CSX 5V UNSWB+ RESETB503 B504 LI_ION C505 100pFR507 0 C502 0.47uF VR5016.8V1 5 HIGH32SWITCH S502 4 LOW Vdda VOLMECH_SWB+ 100pFC503VR506 6.8V 10V VR439L505 390nH 24V 2 1F501 2CR501 1BATT_CODE UNSWB+ BATT – BATT + RADIO_CODEBATTERY_CONTACT CONN_JB5012 DATA 1 NEG 3 POS PB501 1 2SWITCH .01uFC521 6.8V VR440 SB1 1 2PB502 SWITCH C522 .01uFVR441 6.8V PB503 SB2 C523 .01uF6.8V VR442 SWITCH PB504 1 21 2SWITCH VR444 6.8V PTT SB3 6.8V VR4431 2SWITCH PB505 .01uFC520 EMER 47K R506 Q505R505 10K Vdda GREEN_LED IMX1 5 1 6 24 3 SWB+ RED_LEDQ502 680 R501 180 R502 4 13 CR503 2 RTA0 RTA1 RTA2 RTA3 100pFC514 100pFC513 100pFC511 100pFC512SWITCH S501 GND GND1PC3 PC2 C0 C1 PC0 PC1 8 4 C0 C11 2 79 330-400MHz Controls And Switches Schematic Diagram http://www.myradio168.name
6D-16Circuit Board/Schematic Diagrams and Parts List L340 390nHHSMP3820 1 23 CR308 R317 1K 100pF C395C331 100pF 1K R347 R5 C311100K R307 R306 100K CR304 C306 CR305 C312 8.2pF 22nHL305 C313 12pFL306 19.71nH 19.71nHL307 5.1 pFC316 NUNU R305 470 R304 12K C321 100pF C309 100pF R303 1 K Q301 13 2 C307 0.1uF0.1uF C314 180nHL304C315 100pF C310 0.1uF R328 2.7 L303 33nHR340 8.2K 19.71nH L302C308 100pF 100K R301 12pF C302C305 12pF CR301 CR302 5.1pFC303 11pF C304 R302 L301100K 19.71nH1 CR303 23 C301 8.2pF RX_IN 1 SH304 SHIELD 1SHIELDSH302 1 SHIELDSH301 SH303 SHIELD 1 RXFE Top Shield RXFE Bottom Shield Mixer Shield RX Mixer Diode Shield.01uFC380 100K R342 R5DACRx NU C381 R329 0 C318 12pF C3178.2 pFT301 4 6 3 1 2 XFMR TP302T302 XFMR 4 6 3 1 2 C320 C319 7.5pF 1.8pF16.28nHL309 R348 3.6K R336 C333 R5 NU NU 33K R327R316 91K Q315 1 3 2 18K R318 R319 150C396 NU R300 2.2K 1uF C397 1 33.0K RT300 2 R334 Q3161 3 2 VR300 R326NU NU NU NUR325 6.8KR338R335 RT301 21 C391NU NU NU NU R5 C370 100pF R330 RSSI RX_INJ NUR331C372 Q310 13 2 C371 100pF C386 NU NU NU NU0 R349 100pF C374 C378 C373 NU NU C375 VCOBUF 100pF R332L321 0 R339 R5 NU NUR333 NUR309 18 82pF C322 L310 150nH 270 R308 270 R310 23 4 1 CR306 IF [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] [email protected] 1.797V@-50dBm 0.508V 4.396V 2.285V [email protected] [email protected] Note: Rx1 = [email protected] rf signal Rx2 = [email protected] rf signal probed using high impedence probe ZMY0130352-O 330-400MHz Receiver Front End Schematic Diagram http://www.myradio168.name