Home
>
Motorola
>
Portable Radio
>
Motorola Two Way Portable Radio Ht750ls Detailed 6881088c46 E Manual
Motorola Two Way Portable Radio Ht750ls Detailed 6881088c46 E Manual
Have a look at the manual Motorola Two Way Portable Radio Ht750ls Detailed 6881088c46 E Manual online for free. It’s possible to download the document as PDF or print. UserManuals.tech offer 249 Motorola manuals and user’s guides for free. Share the user manual or guide on Facebook, Twitter or Google+.
FMR-2045A-2December 26, 2003 UHF Band 2 Theory of Operation: Synthesizer 41 The Frequency Generation Circuitry is composed of two main ICs: Fractional-N synthesizer (U201) 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 pin 10 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. 4.4 Synthesizer (Refer to “Figure 5-6. UHF Band 2 Synthesizer Schematic Diagram” on page 52.) Figure 4-4. Synthesizer Block Diagram The Fractional-N Synthesizer uses a 16.8 MHz crystal (FL201) to provide a reference for the system. The LVFractN IC (U201) further divides this to 2.1 MHz, 2.225 MHz, and 2.4 MHz as reference frequencies. Together with C206, C207, C208, R204, and CR203, they build up the reference oscillator which is capable of 2.5 ppm stability over temperatures of –30 to 85 °C. It also provides 16.8 MHz at pin 19 of U201 to be used by ASFIC. DATA CLK CEX MODIN V CC, DC5V XTAL1 XTAL2 WARP PREIN VCP REFERENCE OSCILLATOR VOLTAGE MULTIPLIER VOLTAGE CONTROLLED OSCILLATOR 2-POLE LOOP FILTER DATA (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 BIAS2 41 DUAL TRANSIS DUAL TRANSIS-48 5VR5 5, 20, 34, 36 (U248 PIN 5) AUX1 V DD, 3.3VMODOUT U251 LOW VOLTAGE FRACTIONAL-N SYNTHESIZER TORSTORS
December 26, 2003FMR-2045A-2
42UHF Band 2 Theory of Operation: Voltage-Controlled Oscillator (VCO)
The loop filter, which consists 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 the 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.
4.5 Voltage-Controlled Oscillator (VCO)
(Refer to “Figure 5-7. UHF Band 2 Voltage Controlled Oscillator Schematic Diagram” on page 53.
Figure 4-5. VCO Block Diagram
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 20
TX/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
Pin6
RX
TX
(U201 Pin28)Rx-SW
Tx-SW
Vcc-Logic
(U201 Pin28) Steer Line
Voltage
(VCTRL)Pin13
Pin3TRB_IN
LO RF INJECTION
VSFVSF VSF
FMR-2045A-2December 26, 2003 UHF Band 2 Theory of Operation: Voltage-Controlled Oscillator (VCO) 43 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. The VCOBIC (U241) is operated at 4.54V (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 4-1. 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 to “Figure 5-4. UHF Band 2 Receiver Front End Schematic Diagram” on page 50). 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 pin 19, 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 4-1. Level Shifter Logic Desired Mode AUX 4 AUX 3 TRB TxLowHigh (@3.2V)High (@4.8V) Rx High Low Low Battery SaverLowLowHi-Z/Float (@2.5V)
December 26, 2003FMR-2045A-2 This page intentionally left blank. 44UHF Band 2 Theory of Operation: Voltage-Controlled Oscillator (VCO)
Chapter 5 UHF Band 2 CB Layouts, Schematic Diagrams, and Parts List 5.1 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 multimeter 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 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 SEQUENCE LAYER 1 (L1) LAYER 2 (L2) LAYER 3 (L3) LAYER 4 (L4) LAYER 5 (L5) LAYER 6 (L6) INNER LAYERS SIDE 1 SIDE 2
December 26, 2003FMR-2045A-2 This page intentionally left blank. 46UHF Band 2 CB Layouts, Schematic Diagrams, and Parts List: Notes For All Schematics and Circuit Boards
Circuit Board/Schematic Diagrams and Parts List 47 FMR-2045A-2 December 26, 2003 5.2 Circuit Board/Schematic Diagrams and Parts List Figure 5-1. UHF Band 2 (450-527 MHz) Main Board Top Side PCB No. 8486686Z01 C425 C426 C432 1 J400 22 21 8 71 U40532 17 16 1 U406 1 4 5 8 U407C423 E407E408 E409R410 R418 R437 C404C427 C428 C443C444 C471 C472 C473 40 1 21 L401R435 RT400 TP401 TP402 TP410 VR447 VR449 CR413 2220J403 L400 4 3 Q417 R421TP405TP406 TP415 VR434 VR450C441 C490 C491 C492 C493 C494 C495 C496C497 R450 R477C424 C429 R408 R428 R429 R478 R492 SH400 C400 C401 C402 C403C406 C467C480C482 CR412 CR440 Q400 Q403 4 3 Q405 R401R402 R403R405 R406 R407 R416R427 R447 R448 R451R452R453 R454 R455 R456 R476R481 SH401 4 58U400 123 5 PB502 123 5 PB503 B503 B504 6 431 FL201 SH201 TP201 C324C325 C338 2 3 4 56 FL301 L311 L330 SH323 43 2 FL303 123 5 PB504 C349C521 FL302 43 2 FL304 123 5 PB501 R365 VR440 2 Y301 R355 C502 C505 C512 C513 Q502 Q505 R505R506 R507 VR501 C140 C141C511 C514 C5204 3 2 CR503 L116123 5 PB505R501R502 VR443 C101 C102C103 C104 C106C107C188 CR101 CR102 L101 L102 L104 L105 SH100C301 C302 C303 C304 C305 C308 CR301 CR302 L301 L302 R301 R302 SH301 C352 C362 R34245 8 U302 C319 C320 C322 C375 C381 L309L310 R308 R309R310 R348 SH303 6 4 3 T30164 3 T302 TP202 TP302 C203 C210C211 C212 C213 C214C217C220 C228 C229 C230 C233C235 C238 C257C260 C282 C283 C291C292 C294 C297 CR201 L201 L202 L203 L232 4 3 Q210 4 3 Q260 R255 R256U247 C247 C248 C251 C253C271 C272 C273 C276C285 C286 C289 C370 C374C386 3 L243 3 L253 L271L273L282L321 Q241 4 3 Q261 R243 R248 R253R260 R333R339 SH241C109 C110 C111 C112 C113 C114 C115 C116 C117 C118 C119 C120 C121 C122C125C127 C129 C131 C160 C161 C165 C166 C169 C171 C180 C181 L106 L107 L108 L113 L114L115 L117 L160 12 3 Q110 R104R106R107 R108 R120 R161 R171 R173 R174R175R176 R191 SH101 1 16 8 9U101
48Circuit Board/Schematic Diagrams and Parts ListDecember 26, 2003FMR-2045A-2 Figure 5-2. UHF Band 2 (450-527 MHz) Main Board Bottom Side PCB No. 8486686Z01 4 5 32 S502 2C8C 4 S501 2 3 4 1 J101 J102 C108 CR103 CR160 P1004 3 Q111R101R170 C132 C172 C173 CR105 H101 R133 R172 C105 C123 C126 C128 C130 C133 C134 C135 C138C150 C151C152 C170 C174 E101 L112 R102R109 R130 R131R132 R136 117 9 25 U102 C318CR306 CR501 F501 R329 SH304 VR439 C306 C307 C309C310 C311 C312 C313 C314 C315 C316 C317C321 C380 CR303 CR304 CR305L303 L304 L305 L306 L307 Q301 R303 R304 R305 R306 R307 R328 R340 SH302 C252 C254 C255 C256 C371 C372 C373CR251L251 Q310 R251 R252R254R330 R331 R33211 20C241 C242 C378 CR241 CR242 CR243 L241 SH242 1 10 U241 C281 C295L242 L281 R110 R111 R112 R245 R349 C503 C243 C244C245 C246 C250 R241 R242 R244 C407 C419 C420 C421C479 C481R400R413 R425R445 R449 R475 37 C422 C448 R424 C447 R423 R472 R498 R499 R431 C416 C411 C451 125 13 U404 C405 C408 C409 C410 C414 C415C430 C440 R434 R436 VR460 C450C452 C476 4 3 Q410R471 SH40311 1 20 10 U420C475 C442 C445 R473 VR432 VR433 VR445 VR446 VR448 C449 C458 C459 C463 C466C524 C525 C526 C527 C528C529E400E401 R457E402E403 E404 E405 E406 26 C434 C453 C456 L410 L411R409 R411 R432R461 R462 1 76 C435 CR411 Q416 R419 R460 U410C431 C433 C436 C437 3 FL401 R414R415 R420R426 R463 SH402 51 U409C277 C279 C328 C337 C358 C359 C383 C522 C523 R370R371R372R373 R374 R375 R376 R377 U248 1 4 58U303VR441 VR442 VR506 C278 C390 L505 R378 C201 C202 C204 C206C207 C208C218 C219 C223 C224 C231 C232 C234 C258 C259 C263 C264 C265 C293 C296C298 CR203 L261 R201 R202R204 R231 R232 R233 R281 SH202 1 3725 13 U201 5 4 3 U2105 4 3 U211 1 2 3 B501 VR444 C351 C364C367 C385 CR313L325 Q320R320 R321R322R324R345 R346 R360 R363 R364 4 3 2 Y300 C329 C343 C345 C346 C347 C357 CR312 R350 R358 R361SH322 111 20 10 U301 C326C327 C344C348 C360 C361 C366 C382 CR311 L332 Q302 R311R312 R313R314 R315 R344 C334 C350 C355R359 R366 R367 R368R369
Circuit Board/Schematic Diagrams and Parts List49FMR-2045A-2December 26, 2003 Figure 5-3. UHF Band 2 Controls and Switches Schematic Diagram 390nHL505 RADIO_CODE BATTERY_CONTACT BATT- BATT+ B501 CONN_J DATA 2 NEG 1 POS 3 1 2CR501VR439 10V 6.8VVR506 C503 100pF 124V F501 2 BATT_CODE UNSWB+ R507 0 0.47uFC502 C505TAB2 7 2 100pFS502 SWITCH 4 1 LOW5 3 HIGH TAB1 6 VR5016.8V MECH_SWB+ Vdda B503 if B504 LI_ION VOL P100 SB1 SB3 SB2 .01uF C521 C523 .01uF .01uF C522PTT VR442 6.8V VR444 6.8V 6.8V VR441VR440 6.8V SWITCH 3 G1 G2 4 5 G3 2 IN1 OUT G1 G2 4 5 G3 2 IN1 OUT PB502 PB501 SWITCH 3 3 G1 G2 4 5 G3 2 IN1 OUTPB503 SWITCH PB504 SWITCH 3 G1 G2 4 5 G3 2 IN1 OUTQ50224 3Q505 4 13 CR503 25 1 6IMX1 R502 R501 680 18010K R505 R506 47K SWB+ RED_LEDVdda C0C0 C1 C1 7 GND GND1 9 1 PC0 2 PC1 4 PC2 PC38 S501 SWITCH C511 100pFC512 100pFC513 100pFC514 100pF RTA0 RTA1 RTA2 RTA3 DUMMY C520 .01uFVR443 6.8VPB505 SWITCH 3 G1 G2 4 5 G3 2 IN1 OUT EMER GREEN_LED NU8.2pF C141 C140 J102 ANTENNA_NUT 1 TAB1 2 TAB2 3 TAB34 TAB45 TAB5 A1 A2 A3K1 K2 K3 RF_JACK L116 16.28nH 1 2 3if RF_JACKJ101 GND 4 CR160
50Circuit Board/Schematic Diagrams and Parts ListDecember 26, 2003FMR-2045A-2 Figure 5-4. UHF Band 2 Receiver Front End Schematic Diagram RXFE Top Shield1 SHIELDSH301 RXFE Bottom Shield RX Mixer Diod Shield1 SHIELDSH302 SH304 SHIELD 1Mixer ShieldSH303 SHIELD 1 4.3pFC303 CR301 12pF C302 L301 11.03nHR301 100K C301 8.2pF RX_IN100K R302 C304 11pF100pF C305 11.03nH L302CR3023 1 CR303 2 C308 100pF 100pFC307C310 100pF C309 100pF 2.7 R328 1.5K R303 Q301 13 20.1uF C314 R304 12KR305 470 L304 180nHC321 100pFC315 100pF R5 NU 12nHL305 7.5pFC312 C306 NU C311 C313 11pF 11.03nHL306100K R307 CR305 R306 100K 11.03nH L307 CR304C316 4.3pF.01uF C380 R342 100K DACRx 12pF C318 R329 0 8pF C3172 XFMRT301 4 6 3 1 C381 NUL310 150nH R309 0 CR306 3 4 R308 51 82pF C322 NU R310 IF 21 2 T302 XFMR 4 6 3 1 R348 3.6K TP302 9.1pFC320 4.3pF C319 16.28nHL309 C375 100pF 180nHNU L321 R333 100pF C374VCOBUF NU NU 0 R349 C373 C378 12KR339 4.3K R332 Q310 13 2 C386 100pF 240100pF 10K NU C371C372 R331 R330 C370 4.7pF RX_INJ L303 22nH 8.2K R340 R5