Motorola EP450 Service Manual
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Motorola EP450 Service Manual

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  • Page 1 EP450 ™ Portable Radio Detailed Service Manual...
  • Page 3 EP450 Portable Radio Detailed Service Manual VHF 136-162 MHz VHF 146-174 MHz UHF 403-440 MHz UHF 438-470 MHz UHF 465-495 MHz UHF 490-527 MHz Motorola, Inc. 1301 E. Algonquin Road HKLN4216C Schaumburg, IL 60196...

  • Page 4: Product Safety And Rf Exposure Compliance

    Motorola. Furthermore, the purchase of Motorola products shall not be deemed to grant either directly or by implication, estoppel, or otherwise, any license under the copyrights, patents or patent applications of Motorola, except for the normal non-exclusive license to use that arises by operation of law in the sale of a product.

  • Page 5: Table Of Contents

    Table of Contents Table of Contents Foreword ..............................ii Product Safety and RF Exposure Compliance ....................ii Computer Software Copyrights ........................ii Document Copyrights ..........................ii Disclaimer..............................ii List of Figures ..............................x List of Tables ............................xiv Related Publications..........................xiv Chapter 1 Test Equipment, Service Aids, and Service Tools..1-1 Test Equipment..........................
  • Page 6 Table of Contents 4.3.2 Antenna Switch ......................... 4-3 4.3.3 Harmonic Filter........................4-3 4.3.4 Antenna Matching Network....................4-4 4.3.5 Power Control ........................4-4 VHF Frequency Generation Circuitry..................... 4-4 4.4.1 Fractional-N Synthesizer....................4-5 4.4.2 Voltage Controlled Oscillator (VCO) ................. 4-6 Keypad............................4-7 Chapter 5 146-174 MHz VHF Theory Of Operation ......
  • Page 7 Table of Contents Figure 7-9. VHF (136-162 MHz) Controller Interconnect Schematic Diagram (8486769Z02-A) ..7-11 Figure 7-10. VHF (136-162 MHz) Microprocessor Circuitry Schematic Diagram (8486769Z02-A) ... 7-12 Figure 7-11. VHF (136-162 MHz) Audio Circuitry Schematic Diagram (8486769Z02-A) ....7-13 Figure 7-12. VHF (136-162 MHz) DC Regulation Schematic Diagram (8486769Z02-A) ....
  • Page 8 Table of Contents VHF (146-174 MHz) 8486342Z13-C Radio Parts List ................7-55 VHF (146-174 MHz) Keypad Board Parts List (8466565A03-B) ............7-58 Chapter 7 VHF 146-174 MHz Schematic Diagrams, Overlays, and Parts Lists (8486769Z04-C) ........7-59 Figure 7-45. VHF (146-174 MHz) Radio Circuit Block Interconnect Diagram (8486769Z04-C) ..7-59 Figure 7-46.
  • Page 9 Table of Contents 9.3.4 Antenna Matching Network....................9-4 9.3.5 Power Control ........................9-4 UHF Frequency Generation Circuitry .................... 9-4 9.4.1 Fractional-N Synthesizer ....................9-5 9.4.2 Voltage Controlled Oscillator (VCO) ................. 9-6 Keypad............................9-7 Chapter 10 465-495 MHz UHF Theory Of Operation ......10-1 10.1 Introduction ..........................
  • Page 10 viii Table of Contents 13.1.2 Six Layer Circuit Board ....................13-3 13.2 Speaker and Microphone Schematic ................... 13-3 13.2.1 Speaker and Microphone Parts List................13-3 Chapter 13 UHF 403-440 MHz 8486635Z03-O Schematic Diagrams, Overlays, and Parts Lists ..........13-5 Figure 13-3. UHF (403-440 MHz) 8486635Z03-O Radio Circuit Block Diagram ........ 13-5 Figure 13-4.
  • Page 11 Table of Contents Chapter 13 UHF 465-495 MHz 8486634Z02-O Schematic Diagrams, Overlays, and Parts Lists ..........13-41 Figure 13-31. UHF (465-495 MHz) 8486634Z02-O Radio Circuit Block Diagram......13-41 Figure 13-32. UHF (465-495 MHz) 8486634Z02-O Receiver Front End Schematic Diagram ... 13-42 Figure 13-33.

  • Page 12: List Of Figures

    Table of Contents List of Figures Figure 1-1. Programming/Test Cable....................1-4 Figure 1-2. Wiring of the Connectors ....................1-4 Figure 2-1. DC Power Distribution Block Diagram................2-1 Figure 4-1. VHF Receiver Block Diagram................... 4-1 Figure 4-2. VHF Transmitter Block Diagram..................4-3 Figure 4-3.
  • Page 13 Table of Contents Figure 7-33. VHF (146-174 MHz) 8486342Z13-C Receiver Back End Schematic Diagram ....7-43 Figure 7-34. VHF (146-174 MHz) 8486342Z13-C Synthesizer Schematic Diagram ......7-44 Figure 7-35. VHF (146-174 MHz) 8486342Z13-C Voltage Controlled Oscillator Schematic Diagram 7-45 Figure 7-36. VHF (146-174 MHz) 8486342Z13-C Transmitter and Power Control Schematic Diagram..........................
  • Page 14 Table of Contents Figure 13-2. Speaker and Microphone Schematic................13-3 Figure 13-3. UHF (403-440 MHz) 8486635Z03-O Radio Circuit Block Diagram ........ 13-5 Figure 13-4. UHF (403-440 MHz) 8486635Z03-O Receiver Front End Schematic Diagram....13-6 Figure 13-5. UHF (403-440 MHz) 8486635Z03-O Receiver Back End Schematic Diagram ....13-7 Figure 13-6.
  • Page 15 Table of Contents xiii Figure 13-50. UHF (490-527 MHz) 8486768Z02-A Transmitter and Power Control Schematic Diagram........................13-64 Figure 13-51. UHF (490-527 MHz) 8486768Z02-A Controller Interconnect Schematic Diagram ..13-65 Figure 13-52. UHF (490-527 MHz) 8486768Z02-A Microprocessor Circuitry Schematic Diagram ..13-66 Figure 13-53.

  • Page 16: List Of Tables

    Table of Contents List of Tables Table 1-1. Recommended Test Equipment ..................1-1 Table 1-2. Service Aids........................1-2 Table 1-3. Recommended Service Tools ..................1-2 Table 2-1. Voltage Regulators ......................2-2 Table 3-1. Radio Memory Requirements................... 3-1 Table 3-2. SPI Bus Signal Definitions....................3-2 Table 6-1.

  • Page 17: Chapter 1 Test Equipment, Service Aids, And Service Tools

    Chapter 1 Test Equipment, Service Aids, and Service Tools Test Equipment Table 1-1 lists test equipment required to service the EP450 Radios. Table 1-1. Recommended Test Equipment Motorola Part No. Description Characteristics Application R2600 series System analyzer This item will substitute for...

  • Page 18: Service Aids

    Service Aids Table 1-2 lists service aids recommended for working on the EP450 Radios. While all of these items are available from Motorola, most are standard shop equipment items, and any equivalent item capable of the same performance may be substituted for the item listed.
  • Page 19 Test Equipment, Service Aids, and Service Tools: Service Aids Table 1-3. Recommended Service Tools (Continued) Motorola Part Description Application RLN4062 Hot air workstation, 120 V Tool for hot air soldering/desoldering of surface mounted integrated circuits 0180386A78 Illuminated magnifying glass with...

  • Page 20: Figure 1-1. Programming/Test Cable

    Test Equipment, Service Aids, and Service Tools: Service Aids Programming/Test Cable 25 POSITION 25 POSITION MALE CONNECTOR FEMALE CONNECTOR 36.0” CABLE 36.0” CABLE Figure 1-1. Programming/Test Cable 25 pin Male D Connector Components molded inside 2.5mm stereo and 3.5mm Orange 3.5mm Tip (Speaker +) Blue...

  • Page 21: Chapter 2 Dc Power Distribution

    Chapter 2 DC Power Distribution DC Regulation and Distribution A block diagram of the DC power distribution throughout the radio is shown in Figure 2-1. Accessories 20 pin Connector Audio Power Keypad/Option Board Amplifier Vdda Vdda Regulator UNSWB+ SWB+ 7.5V Vddd Vddd Battery...

  • Page 22: Table 2-1. Voltage Regulators

    DC Power Distribution: DC Regulation and Distribution When the radio is turned on, SWB+ is present and is applied to: • transistor switch Q494 (pins 1 and 6) which turns on Q493 • RX audio power amplifier U490 • voltage divider R420/R421 and port PE0, a microprocessor A/D input which measures battery voltage and radio on/off status The output of FET switch Q493 is applied to the control pins of regulators U310, U320 and U330, turning them on.

  • Page 23: Chapter 3 Controller Theory Of Operation

    7-39 and 7-40). 3.1.1 Microprocessor Circuitry The microprocessor circuitry includes microprocessor (U401) and associated EEPROM, S-RAM (not used in EP450 models), and Flash ROM memories. The following memory IC's are used: Table 3-1. Radio Memory Requirements Reference No. Description Type...

  • Page 24: Memory Usage

    Controller Theory of Operation: Controller 3.1.1.1 Memory Usage Radio operation is controlled by software that is stored in external Flash ROM memory (U404). Radio parameters and customer specific information is stored in external EEPROM (U402). The operating status of the radio is maintained in RAM located within the microprocessor. When the radio is turned off, the operating status of the radio is written to EEPROM before operating voltage is removed from the microprocessor.

  • Page 25: Interface To Rss Programming

    Controller Theory of Operation: Controller In order for each circuit block to respond only to the data intended for it, each peripheral has its own chip select (or chip enable) line. The device will only respond to data when its enable line is pulled low by one of the microprocessor ports, as follows: •...

  • Page 26: Boot Mode Control

    Controller Theory of Operation: Controller The microprocessor reset line (pin 94) can be controlled directly by the digital 3.3 V regulator (U320 pin 7), the microphone jack (part of accessory connector J471) via Q472 and Q471, and the microprocessor itself. U320 pulls the reset line low if the digital 3.3 V source loses regulation. This prevents possible MOS latch-up or overwriting of registers in the microprocessor because the reset line is higher in voltage than the microprocessor VDD ports (U401 pins 12, 39, 59, 88).

  • Page 27: Audio Power Amplifier

    The Motorola RLN4460 Portable Test Set and AAPMKN4004 Programming Test Cable provide the proper interface between the radio's ungrounded audio output and ground-referenced test equipment.

  • Page 28: Vox Operation

    Controller Theory of Operation: Controller 3.1.2.5 VOX Operation VOX audio accessories do not have a PTT switch. Instead, the mic cartridge is wired directly from J471-4 to ground. If the radio has been programmed for VOX operation and the VOX accessory is plugged in prior to turning the radio on, the current drawn by the cartridge will turn on Q470 (pins 3- 4-5) and a logic high will be seen at port PJ1 at turn-on.

  • Page 29: Chapter 4 136-162 Mhz Vhf Theory Of Operation

    Chapter 4 136-162 MHz VHF Theory Of Operation Introduction This chapter provides a detailed theory of operation for the radio components. Schematic diagrams for the circuits described in the following paragraphs are located in Chapter 7 of this manual. VHF Receiver The VHF receiver covers the range of 136-162 MHz and provides switchable IF bandwidth for use with 12.5 kHz or 20/25 kHz channel spacing systems.

  • Page 30: Receiver Back-End

    136-162 MHz VHF Theory Of Operation: VHF Receiver constant at 6.2 mA regardless of device and temperature variations, for optimum dynamic range and noise figure. The output of the RF amplifier is applied to the interstage filter, a fixed-tuned 3-pole series-coupled resonator design having a 3 dB bandwidth of 54 MHz and insertion loss of 1.8 dB.

  • Page 31: Vhf Transmitter

    136-162 MHz VHF Theory Of Operation: VHF Transmitter VHF Transmitter The VHF transmitter covers the range of 136-162 MHz. Depending on model, the output power of the transmitter is either switchable on a per-channel basis between high power (5 watts) and low power (1 watt), or is factory preset to 2 watts.

  • Page 32: Antenna Matching Network

    136-162 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry 4.3.4 Antenna Matching Network The harmonic filter presents a 50 Ω impedance to antenna jack J140. A matching network, made up of C140-C141 and L140, is used to match the antenna impedance to the harmonic filter. This optimizes the performance of the transmitter and receiver into the impedance presented by the antenna, significantly improving the antenna's efficiency.

  • Page 33: Fractional-N Synthesizer

    136-162 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry Transmit modulation from the ASFICcmp (U451 pin 40) is applied to U201 pin 10 (MOD_IN). An electronic attenuator in the ASFICcmp adjusts overall transmitter deviation by varying the audio level applied to the synthesizer IC.

  • Page 34: Voltage Controlled Oscillator (Vco)

    136-162 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry One of the auxiliary outputs of the synthesizer IC (AUX3, U201 pin 2) provides the TRB signal which determines the operating mode of the VCO, either receive or transmit. DATA (U401 Pin 100) DATA LOCK LOCK (U401 Pin 56)

  • Page 35: Keypad

    136-162 MHz VHF Theory Of Operation: Keypad C267, and varactor D261. High-port audio modulation from the synthesizer IC is applied as VCO_MOD to varactor D262 which modulates the transmit VCO. AUX3 (U201 Pin 2) TRB_IN Pin 20 Pin 19 Pin 7 TX/RX/BS Pin 13 Switching Network...
  • Page 36 136-162 MHz VHF Theory Of Operation: Keypad Notes: June, 2005 HKLN4216C...

  • Page 37: Chapter 5 146-174 Mhz Vhf Theory Of Operation

    Chapter 5 146-174 MHz VHF Theory Of Operation Introduction This chapter provides a detailed theory of operation for the radio components. Schematic diagrams for the circuits described in the following paragraphs are located in Chapter 7 of this manual. VHF Receiver The VHF receiver covers the range of 146-174 MHz and provides switchable IF bandwidth for use with 12.5 kHz or 20/25 kHz channel spacing systems.

  • Page 38: Receiver Back-End

    146-174 MHz VHF Theory Of Operation: VHF Receiver constant at 6.2 mA regardless of device and temperature variations, for optimum dynamic range and noise figure. The output of the RF amplifier is applied to the interstage filter, a fixed-tuned 3-pole series-coupled resonator design having a 3 dB bandwidth of 58 MHz and insertion loss of 1.8 dB.

  • Page 39: Vhf Transmitter

    146-174 MHz VHF Theory Of Operation: VHF Transmitter VHF Transmitter The VHF transmitter covers the range of 146-174 MHz. Depending on model, the output power of the transmitter is either switchable on a per-channel basis between high power (5 watts) and low power (1 watt).

  • Page 40: Antenna Matching Network

    146-174 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry 5.3.4 Antenna Matching Network The harmonic filter presents a 50 Ω impedance to antenna jack J140. A matching network, made up of C140-C141 and L140, is used to match the antenna impedance to the harmonic filter. This optimizes the performance of the transmitter and receiver into the impedance presented by the antenna, significantly improving the antenna's efficiency.

  • Page 41: Fractional-N Synthesizer

    146-174 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry Transmit modulation from the ASFICcmp (U451 pin 40) is applied to U201 pin 10 (MOD_IN). An electronic attenuator in the ASFICcmp adjusts overall transmitter deviation by varying the audio level applied to the synthesizer IC.

  • Page 42: Voltage Controlled Oscillator (Vco)

    146-174 MHz VHF Theory Of Operation: VHF Frequency Generation Circuitry One of the auxiliary outputs of the synthesizer IC (AUX3, U201 pin 2) provides the TRB signal which determines the operating mode of the VCO, either receive or transmit. DATA (U401 Pin 100) DATA LOCK LOCK (U401 Pin 56)

  • Page 43: Keypad

    146-174 MHz VHF Theory Of Operation: Keypad C267, and varactor D261. High-port audio modulation from the synthesizer IC is applied as VCO_MOD to varactor D262 which modulates the transmit VCO. AUX3 (U201 Pin 2) TRB_IN Pin 20 Pin 19 Pin 7 TX/RX/BS Pin 13 Switching Network...
  • Page 44 146-174 MHz VHF Theory Of Operation: Keypad Notes: June, 2005 HKLN4216C...

  • Page 45: Chapter 6 Vhf Troubleshooting Tables

    Chapter 6 VHF Troubleshooting Tables Troubleshooting Table for Receiver Table 6-1. Troubleshooting Table for Receiver Symptom Possible Causes Procedure Corrective Action Radio Dead (no 1. Battery dead or defec- Substitute known good battery or Charge or replace battery. turn-on beep, no tive.
  • Page 46 VHF Troubleshooting Tables: Troubleshooting Table for Receiver Table 6-1. Troubleshooting Table for Receiver (Continued) Symptom Possible Causes Procedure Corrective Action No Audio 1. Synthesizer out of lock Verify U201-4 is at 3 V dc. Troubleshoot synthesizer/VCO circuits. 2. Defective IFIC Verify audio is present at U51-8.

  • Page 47: Troubleshooting Table For Synthesizer

    VHF Troubleshooting Tables: Troubleshooting Table for Synthesizer Troubleshooting Table for Synthesizer Table 6-2. Troubleshooting Table for Synthesizer Symptom Possible Causes Procedure Corrective Action Synthesizer Out of 1. VCO fault Verify oscillator is working, check RF Check VCO tank components Lock (RX mode level at U251-10 per schematic.

  • Page 48: Troubleshooting Table For Transmitter

    VHF Troubleshooting Tables: Troubleshooting Table for Transmitter Troubleshooting Table for Transmitter Table 6-3. Troubleshooting Table for Transmitter Symptom Possible Causes Procedure Corrective Action No Transmit (no TX 1. PTT switch defective. Verify U401-71 goes low when PTT Replace PTT switch S441. LED indication) is pressed.
  • Page 49 VHF Troubleshooting Tables: Troubleshooting Table for Transmitter Table 6-3. Troubleshooting Table for Transmitter (Continued) Symptom Possible Causes Procedure Corrective Action Low Power 1. Low TX injection Check that RF level at jct. R100/ Check U251, L291-292, C290- R101 per schematic. 291.
  • Page 50 VHF Troubleshooting Tables: Troubleshooting Table for Transmitter Table 6-3. Troubleshooting Table for Transmitter (Continued) Symptom Possible Causes Procedure Corrective Action No EXT MIC audio 1. Mic bias fault Verify approx 1.8 V dc across EXT Check Q470. R475, R477, MIC cartridge in TX mode. Verify L471.

  • Page 51: Troubleshooting Table For Board And Ic Signals

    VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Troubleshooting Table for Board and IC Signals Table 6-4. Troubleshooting Table for Board and IC Signals IC Designator Pin Function DC Voltage Comments (Condition) RF input 44.85 MHz 1.20 IFIC RF input decoupling 1.20 2nd LO osc output...
  • Page 52 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U110 RF input (TX mode) RF Power Amp Vgg (gate bias) 2.65 (typ) (TX mode) (4.25 V typ at VHF) 6.59 (TX mode)
  • Page 53 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U201 Ref osc XTAL2 Freq Synthesizer Ref osc warp output 3.00 Superfilter cap 4.48 Superfilter base (NU) 3.76...
  • Page 54 6-10 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U251 Prescaler output 2.26 VCO / Buffer TX switch output (NU) 0.06 Vcc_BUFFERS 3.00...
  • Page 55 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 6-11 Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U401 PB1_ADDR9 3.05 Microprocessor PB2_ADDR10 0.16 3.23 PBO_ADDR8 3.05 PB5_ADDR13 0.13 PG1_XA14 0.20 PG4_XA17...
  • Page 56 6-12 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U401 PH1_PW2 3.00 Microprocessor PH0_PW1 3.23 Synth chip select XIRQ 3.00 1.48 RX enable 0.01...
  • Page 57 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 6-13 Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U401 PA3_IC4_OC5_OC1 3.00 Microprocessor PA4_OC4_OC1 Squelch detect input PA5_OC3_OC1 Channel activity input PA6_OC2_OC1 PA7_PA1_OC1 VSSR...
  • Page 58 6-14 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U404 3.17 Flash ROM 0.30 0.22 3.03 3.08 3.06 0.24 3.08 3.05 3.05 0.69...
  • Page 59 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 6-15 Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U451 GCB1 general purpose output ASFIC_CMP GCB0 general purpose output 3.00 BW select (25 kHz mode) Squelch channel activity output To U401-84...
  • Page 60 6-16 VHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Notes: Table 6-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U480 Unit 1 output 2.48 Dual Opamp Unit 1 (-) input 2.48 Unit 1 (+) input 2.46...

  • Page 61: Chapter 7 Vhf Schematic Diagrams, Overlays, And Parts Lists

    (pF) or microfarads (µF), and inductance values are in nanohenries (nH) or micro- henries (µH). 2. DC voltages are measured from point indicated to chassis ground using a Motorola DC multi- meter or equivalent. If the board has been removed from the chassis, the transmitter module mounting screws may be used for ground connection.
  • Page 62 VHF Schematic Diagrams, Overlays, and Parts Lists: Introduction Ref. No. Series Circuit Block 301-400 DC Regulation 401-450 Microprocessor 451-550 Audio 7. Circuit Block Interconnection Legend: Name Description USWB+ Unswitched Battery Voltage (always on) 5 volts (regulated) 5 volts in RX mode only 5 volts in TX mode only RESET Low-line reset signal from U320 to uP...

  • Page 63: Six Layer Circuit Board

    Speaker and Microphone Schematic MATES WITH J470 ON RADIO BOARD MATES WITH J491 ON RADIO BOARD Figure 7-2. Speaker and Microphone Schematic 7.2.1 Speaker and Microphone Parts List Reference Motorola Part Description Designator 5085880L01 Microphone, electret 5085738Z08 Speaker assembly with connector HKLN4216C...
  • Page 64 VHF Schematic Diagrams, Overlays, and Parts Lists: Speaker and Microphone Schematic Notes: June, 2005 HKLN4216C...

  • Page 65: Chapter 8 403-440 Mhz Uhf Theory Of Operation

    Chapter 8 403-440 MHz UHF Theory Of Operation Introduction This chapter provides a detailed theory of operation for the radio components. Schematic diagrams for the circuits described in the following paragraphs are located in Chapter 13 of this manual. UHF Receiver The UHF receiver covers the range of 403-440 MHz and provides switchable IF bandwidth for use with 20/25/30 kHz or 12.5 kHz channel spacing systems.

  • Page 66: Receiver Back End

    403-440 MHz UHF Theory Of Operation: UHF Receiver The output of the RF amplifier is applied to the interstage filter, a fixed-tuned 4-pole Butterworth shunt-coupled resonator design having a 3 dB bandwidth of 68 MHz centered at 462 MHz, and insertion loss of 3.5 dB.

  • Page 67: Uhf Transmitter

    403-440 MHz UHF Theory Of Operation: UHF Transmitter UHF Transmitter The UHF transmitter covers the range of 403-440 MHz. Depending on model, the output power of the transmitter is either switchable on a per-channel basis between high power (4 watts) and low power (1 watt), or is factory preset to 2 watts.

  • Page 68: Antenna Matching Network

    403-440 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry 8.3.4 Antenna Matching Network The harmonic filter presents a 50Ω impedance to antenna jack J140. A matching network, made up of C140-C141 and L140, is used to match the antenna impedance to the harmonic filter. This optimizes the performance of the transmitter and receiver into the impedance presented by the antenna, significantly improving the antenna's efficiency.

  • Page 69: Fractional-N Synthesizer

    403-440 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry SPI_CLK, and SYNTH_CS (chip select) lines (U409 pins 100, 1 and 47 respectively). A logic high (3 V) from U201 pin 4 indicates to the microprocessor that the synthesizer is locked. Buffer Voltage Q280...

  • Page 70: Voltage Controlled Oscillator (Vco)

    403-440 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry One of the auxiliary outputs of the synthesizer IC (AUX3, U201 pin 2) provides the TRB signal which determines the operating mode of the VCO, either receive or transmit. DATA (U401 Pin 100) DATA LOCK LOCK (U401 Pin 56)

  • Page 71: Keypad

    403-440 MHz UHF Theory Of Operation: Keypad C267, and varactor D261. High-port audio modulation from the synthesizer IC is applied as VCO_MOD to varactor D262 which modulates the transmit VCO. AUX3 (U201 Pin 2) TRB_IN Pin 20 Pin 19 Pin 7 TX/RX/BS Pin 13 Switching Network...
  • Page 72 403-440 MHz UHF Theory Of Operation: Keypad Notes: June, 2005 HKLN4216C...

  • Page 73: Chapter 9 438-470 Mhz Uhf Theory Of Operation

    Chapter 9 438-470 MHz UHF Theory Of Operation Introduction This chapter provides a detailed theory of operation for the radio components. Schematic diagrams for the circuits described in the following paragraphs are located in Chapter 13 of this manual. UHF Receiver The UHF receiver covers the range of 438-470 MHz and provides switchable IF bandwidth for use with 20/25/30 kHz or 12.5 kHz channel spacing systems.

  • Page 74: Receiver Back End

    438-470 MHz UHF Theory Of Operation: UHF Receiver The output of the RF amplifier is applied to the interstage filter, a fixed-tuned 4-pole Butterworth shunt-coupled resonator design having a 3 dB bandwidth of 68 MHz centered at 462 MHz, and insertion loss of 3 dB.

  • Page 75: Uhf Transmitter

    438-470 MHz UHF Theory Of Operation: UHF Transmitter UHF Transmitter The UHF transmitter covers the range of 438-470 MHz. Depending on model, the output power of the transmitter is either switchable on a per-channel basis between high power (4 watts) and low power (1 watt).

  • Page 76: Antenna Matching Network

    438-470 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry 9.3.4 Antenna Matching Network The harmonic filter presents a 50Ω impedance to antenna jack J140. A matching network, made up of C140-C141 and L140, is used to match the antenna impedance to the harmonic filter. This optimizes the performance of the transmitter and receiver into the impedance presented by the antenna, significantly improving the antenna's efficiency.

  • Page 77: Fractional-N Synthesizer

    438-470 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry SPI_CLK, and SYNTH_CS (chip select) lines (U409 pins 100, 1 and 47 respectively). A logic high (3 V) from U201 pin 4 indicates to the microprocessor that the synthesizer is locked. Buffer Voltage Q280...

  • Page 78: Voltage Controlled Oscillator (Vco)

    438-470 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry One of the auxiliary outputs of the synthesizer IC (AUX3, U201 pin 2) provides the TRB signal which determines the operating mode of the VCO, either receive or transmit. DATA (U401 Pin 100) DATA LOCK LOCK (U401 Pin 56)

  • Page 79: Keypad

    438-470 MHz UHF Theory Of Operation: Keypad C267, and varactor D261. High-port audio modulation from the synthesizer IC is applied as VCO_MOD to varactor D262 which modulates the transmit VCO. AUX3 (U201 Pin 2) TRB_IN Pin 20 Pin 19 Pin 7 TX/RX/BS Pin 13 Switching Network...
  • Page 80 438-470 MHz UHF Theory Of Operation: Keypad Notes: June, 2005 HKLN4216C...

  • Page 81: Chapter 10 465-495 Mhz Uhf Theory Of Operation

    Chapter 10 465-495 MHz UHF Theory Of Operation 10.1 Introduction This chapter provides a detailed theory of operation for the radio components. Schematic diagrams for the circuits described in the following paragraphs are located in Chapter 13 of this manual. 10.2 UHF Receiver The UHF receiver covers the range of 465-495 MHz and provides switchable IF bandwidth for use with 20/25/30 kHz or 12.5 kHz channel spacing systems.

  • Page 82: Receiver Back End

    10-2 465-495 MHz UHF Theory Of Operation: UHF Receiver The output of the RF amplifier is applied to the interstage filter, a fixed-tuned 4-pole Butterworth shunt-coupled resonator design having a 3 dB bandwidth of 68 MHz centered at 480 MHz, and insertion loss of 3.3 dB.

  • Page 83: Uhf Transmitter

    465-495 MHz UHF Theory Of Operation: UHF Transmitter 10-3 10.3 UHF Transmitter The UHF transmitter covers the range of 465-495 MHz. Depending on model, the output power of the transmitter is either switchable on a per-channel basis between high power (4 watts) and low power (1 watt), or is factory preset to 2 watts.

  • Page 84: Antenna Matching Network

    10-4 465-495 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry 10.3.4 Antenna Matching Network The harmonic filter presents a 50Ω impedance to antenna jack J140. A matching network, made up of C140-C141 and L140, is used to match the antenna impedance to the harmonic filter. This optimizes the performance of the transmitter and receiver into the impedance presented by the antenna, significantly improving the antenna's efficiency.

  • Page 85: Fractional-N Synthesizer

    465-495 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry 10-5 SPI_CLK, and SYNTH_CS (chip select) lines (U409 pins 100, 1 and 47 respectively). A logic high (3 V) from U201 pin 4 indicates to the microprocessor that the synthesizer is locked. Buffer Voltage Q280...

  • Page 86: Voltage Controlled Oscillator (Vco)

    10-6 465-495 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry One of the auxiliary outputs of the synthesizer IC (AUX3, U201 pin 2) provides the TRB signal which determines the operating mode of the VCO, either receive or transmit. DATA (U401 Pin 100) DATA LOCK...

  • Page 87: Keypad

    465-495 MHz UHF Theory Of Operation: Keypad 10-7 C267, and varactor D261. High-port audio modulation from the synthesizer IC is applied as VCO_MOD to varactor D262 which modulates the transmit VCO. AUX3 (U201 Pin 2) TRB_IN Pin 20 Pin 19 Pin 7 TX/RX/BS Pin 13...
  • Page 88 10-8 465-495 MHz UHF Theory Of Operation: Keypad Notes: June, 2005 HKLN4216C...

  • Page 89: Chapter 11 490-527 Mhz Uhf Theory Of Operation

    Chapter 11 490-527 MHz UHF Theory Of Operation 11.1 Introduction This chapter provides a detailed theory of operation for the radio components. Schematic diagrams for the circuits described in the following paragraphs are located in Chapter 13 of this manual. 11.2 UHF Receiver The UHF receiver covers the range of 490-527 MHz and provides switchable IF bandwidth for use with 20/25/30 kHz or 12.5 kHz channel spacing systems.

  • Page 90: Receiver Back End

    11-2 490-527 MHz UHF Theory Of Operation: UHF Receiver The output of the RF amplifier is applied to the interstage filter, a fixed-tuned 4-pole Butterworth shunt-coupled resonator design having a 3 dB bandwidth of 68 MHz centered at 480 MHz, and insertion loss of 3.3 dB.

  • Page 91: Uhf Transmitter

    490-527 MHz UHF Theory Of Operation: UHF Transmitter 11-3 11.3 UHF Transmitter The UHF transmitter covers the range of 490-527 MHz. Depending on model, the output power of the transmitter is either switchable on a per-channel basis between high power (4 watts) and low power (1 watt), or is factory preset to 2 watts.

  • Page 92: Antenna Matching Network

    11-4 490-527 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry 11.3.4 Antenna Matching Network The harmonic filter presents a 50Ω impedance to antenna jack J140. A matching network, made up of C140-C141 and L140, is used to match the antenna impedance to the harmonic filter. This optimizes the performance of the transmitter and receiver into the impedance presented by the antenna, significantly improving the antenna's efficiency.

  • Page 93: Fractional-N Synthesizer

    490-527 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry 11-5 SPI_CLK, and SYNTH_CS (chip select) lines (U409 pins 100, 1 and 47 respectively). A logic high (3 V) from U201 pin 4 indicates to the microprocessor that the synthesizer is locked. Buffer Voltage Q280...

  • Page 94: Voltage Controlled Oscillator (Vco)

    11-6 490-527 MHz UHF Theory Of Operation: UHF Frequency Generation Circuitry One of the auxiliary outputs of the synthesizer IC (AUX3, U201 pin 2) provides the TRB signal which determines the operating mode of the VCO, either receive or transmit. DATA (U401 Pin 100) DATA LOCK...

  • Page 95: Keypad

    490-527 MHz UHF Theory Of Operation: Keypad 11-7 C267, and varactor D261. High-port audio modulation from the synthesizer IC is applied as VCO_MOD to varactor D262 which modulates the transmit VCO. AUX3 (U201 Pin 2) TRB_IN Pin 20 Pin 19 Pin 7 TX/RX/BS Pin 13...
  • Page 96 11-8 490-527 MHz UHF Theory Of Operation: Keypad Notes: June, 2005 HKLN4216C...

  • Page 97: Table 12-1. Troubleshooting Table For Receiver

    Chapter 12 UHF Troubleshooting Tables 12.1 Troubleshooting Table for Receiver Table 12-1. Troubleshooting Table for Receiver Symptom Possible Causes Procedure Corrective Action Radio Dead (no 1. Battery dead or defec- Substitute known good battery or Charge or replace battery. turn-on beep, no tive.
  • Page 98 12-2 UHF Troubleshooting Tables: Troubleshooting Table for Receiver Table 12-1. Troubleshooting Table for Receiver (Continued) Symptom Possible Causes Procedure Corrective Action No Audio 1. Synthesizer out of lock Verify U201-4 is at 3V dc. Troubleshoot synthesizer/VCO circuits. 2. Defective IFIC Verify audio is present at U51-8.

  • Page 99: Table 12-2. Troubleshooting Table For Synthesizer

    UHF Troubleshooting Tables: Troubleshooting Table for Synthesizer 12-3 12.2 Troubleshooting Table for Synthesizer Table 12-2. Troubleshooting Table for Synthesizer Symptom Possible Causes Procedure Corrective Action Synthesizer Out of 1. VCO fault Verify oscillator is working, check RF Check VCO tank components Lock (RX mode level at U251-10 per schematic.

  • Page 100: Table 12-3. Troubleshooting Table For Transmitter

    12-4 UHF Troubleshooting Tables: Troubleshooting Table for Transmitter 12.3 Troubleshooting Table for Transmitter Table 12-3. Troubleshooting Table for Transmitter Symptom Possible Causes Procedure Corrective Action No Transmit (no TX 1. PTT switch defective. Verify U401-71 goes low when PTT Replace PTT switch S441. LED indication) is pressed.
  • Page 101 UHF Troubleshooting Tables: Troubleshooting Table for Transmitter 12-5 Table 12-3. Troubleshooting Table for Transmitter (Continued) Symptom Possible Causes Procedure Corrective Action Poor TX range, 1. RF test jack defective Verify continuity of J140 pins 3 and 4 Replace J140. conducted power in RX mode only.

  • Page 102: Table 12-4. Troubleshooting Table For Board And Ic Signals

    12-6 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 12.4 Troubleshooting Table for Board and IC Signals Table 12-4. Troubleshooting Table for Board and IC Signals IC Designator Pin Function DC Voltage Comments (Condition) RF input 44.85 MHz 1.20 IFIC RF input decoupling...
  • Page 103 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 12-7 Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U110 RF input (TX mode) RF Power Amp Vgg (gate bias) 2.65 (typ) (TX mode) (4.25V typ at VHF) 6.59...
  • Page 104 12-8 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U201 Ref osc XTAL2 Freq Synthesizer Ref osc warp output 3.00 Superfilter cap 4.48 Superfilter base (NU)
  • Page 105 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 12-9 Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U251 Prescaler output 2.26 VCO / Buffer TX switch output (NU) 0.06 Vcc_BUFFERS 3.00...
  • Page 106 12-10 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U401 PB1_ADDR9 3.05 Microprocessor PB2_ADDR10 0.16 3.23 PBO_ADDR8 3.05 PB5_ADDR13 0.13 PG1_XA14 0.20 PG4_XA17...
  • Page 107 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 12-11 Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U401 PH1_PW2 3.00 Microprocessor PH0_PW1 3.23 Synth chip select XIRQ 3.00 1.48 RX enable 0.01...
  • Page 108 12-12 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U401 PA3_IC4_OC5_OC1 3.00 Microprocessor PA4_OC4_OC1 Squelch detect input PA5_OC3_OC1 Channel activity input PA6_OC2_OC1 PA7_PA1_OC1 VSSR...
  • Page 109 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 12-13 Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U404 3.17 Flash ROM 0.30 0.22 3.03 3.08 3.06 0.24 3.08 3.05 3.05 0.69...
  • Page 110 12-14 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U451 GCB1 general purpose output ASFIC_CMP GCB0 general purpose output 3.00 BW select (25 kHz mode) Squelch channel activity output To U401-84...
  • Page 111 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals 12-15 Table 12-4. Troubleshooting Table for Board and IC Signals (Continued) IC Designator Pin Function DC Voltage Comments (Condition) U480 Unit 1 output 2.48 Dual Opamp Unit 1 (-) input 2.48 Unit 1 (+) input 2.46...
  • Page 112 12-16 UHF Troubleshooting Tables: Troubleshooting Table for Board and IC Signals Notes: June, 2005 HKLN4216C...

  • Page 113: Overlays, And Parts Lists

    (pF) or microfarads (µF), and inductance values are in nanohenries (nH) or micro- henries (µH). 2. DC voltages are measured from point indicated to chassis ground using a Motorola DC multi- meter or equivalent. If the board has been removed from the chassis, the transmitter module mounting screws may be used for ground connection.
  • Page 114 13-2 UHF Schematic Diagrams, Overlays, and Parts Lists: Introduction Ref. No. Series Circuit Block 301-400 DC Regulation 401-450 Microprocessor 451-550 Audio 7. Circuit Block Interconnection Legend: Name Description USWB+ Unswitched Battery Voltage (always on) 5 volts (regulated) 5 volts in RX mode only 5 volts in TX mode only RESET Low-line reset signal from U320 to uP...

  • Page 115: Six Layer Circuit Board

    13.2 Speaker and Microphone Schematic MATES WITH J470 ON RADIO BOARD MATES WITH J491 ON RADIO BOARD Figure 13-2. Speaker and Microphone Schematic 13.2.1 Speaker and Microphone Parts List Reference Motorola Part Description Designator 5085880L01 Microphone, electret 5085738Z08 Speaker assembly with connector...
  • Page 116 13-4 UHF Schematic Diagrams, Overlays, and Parts Lists: Speaker and Microphone Schematic Notes: June, 2005 HKLN4216C...

  • Page 117: Index

    INDEX Antenna Matching Network, UHF 403-440 MHz Theory Of Operation .......8-4 Antenna Matching Network, UHF 438-470 MHz Theory Of Operation .......9-4 Antenna Matching Network, UHF 465-495 MHz Theory Of Operation ......10-4 Antenna Matching Network, UHF 490-527 MHz Theory Of Operation ......11-4 Antenna Matching Network, VHF 136-162 MHz Theory Of Operation........4-4 Antenna Matching Network, VHF 146-174 MHz Theory Of Operation........5-4 Antenna Switch, UHF 403-440 MHz Theory Of Operation..........8-3...
  • Page 118 INDEX: DC Power Distribution Theory of Operation................2-1 DC Regulation and Distribution Theory of Operation............2-1 Disclaimer ..........................ii Document Copyrights......................ii Foreword ..........................ii Fractional-N Synthesizer, UHF 403-440 MHz Theory Of Operation ........8-5 Fractional-N Synthesizer, UHF 438-470 MHz Theory Of Operation ........9-5 Fractional-N Synthesizer, UHF 465-495 MHz Theory Of Operation .........10-5 Fractional-N Synthesizer, UHF 490-527 MHz Theory Of Operation .........

  • Page 119: Notes For All Schematics And Circuit Boards

    INDEX: Keypad, UHF 403-440 MHz Theory Of Operation ..............8-7 Keypad, UHF 438-470 MHz Theory Of Operation ..............9-7 Keypad, UHF 465-495 MHz Theory Of Operation ............10-7 Keypad, UHF 490-527 MHz Theory Of Operation ............11-7 Keypad, VHF 136-162 MHz Theory Of Operation...............4-7 Keypad, VHF 146-174 MHz Theory Of Operation...............5-7 List of Figures.........................

  • Page 120: Six Layer Circuit Board

    INDEX: Receiver Front-End, VHF 136-162 MHz Theory Of Operation ...........4-1 Receiver Front-End, VHF 146-174 MHz Theory Of Operation ...........5-1 Receiver, UHF 403-440 MHz Theory Of Operation ............8-1 Receiver, UHF 438-470 MHz Theory Of Operation ............9-1 Receiver, UHF 465-495 MHz Theory Of Operation ............10-1 Receiver, UHF 490-527 MHz Theory Of Operation ............
  • Page 121 INDEX: UHF Schematic Diagrams, Overlays, and Parts Lists ............12-1 Introduction........................12-1 Notes For All Schematics and Circuit Boards............12-1 Six Layer Circuit Board..................12-3 Speaker and Microphone Schematic................12-3 Speaker and Microphone Parts List...............12-3 UHF 403-440 MHz Theory Of Operation................8-1 Introduction........................8-1 UHF Receiver........................8-1 Receiver Front End....................8-1 Receiver Back End ....................8-2 UHF Transmitter ......................8-3 Transmitter Power Amplifier ................8-3...
  • Page 122 INDEX: Fractional-N Synthesizer ..................10-5 Voltage Controlled Oscillator (VCO)..............10-6 Keypad ........................10-7 UHF 490-527 MHz Theory Of Operation ................11-1 Introduction ......................... 11-1 UHF Receiver......................11-1 Receiver Front End ....................11-1 Receiver Back End....................11-2 UHF Transmitter......................11-3 Transmitter Power Amplifier .................. 11-3 Antenna Switch .....................
  • Page 123 INDEX: Receiver Front-End ....................5-1 Receiver Back-End....................5-2 VHF Transmitter ......................5-3 Transmit Power Amplifier ..................5-3 Antenna Switch......................5-3 Harmonic Filter ......................5-3 Antenna Matching Network ..................5-4 Power Control......................5-4 VHF Frequency Generation Circuitry ................5-4 Fractional-N Synthesizer ..................5-5 Voltage Controlled Oscillator (VCO) ................5-6 Keypad ..........................5-7 VHF Troubleshooting Tables ....................6-1 Troubleshooting Table for Receiver................6-1 Troubleshooting Table for Synthesizer ................6-3 Troubleshooting Table for Transmitter ................6-4...
  • Page 124 INDEX: Notes: June, 2005 HKLN4216C...
  • Page 126 MOTOROLA and the Stylized M Logo are registered in the U.S. Patent and Trademark Office. All other product or service names are the property of their respective owners. © Motorola, Inc. 2005 © *HKLN4216C* HKLN4216C...

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