Motorola Cm Vhf1 136 162mhz Low Power Manual
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Commercial Series CM Radios VHF1 (136-162MHz) Low Power Service Information Issue: October 2004
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iii Table of Contents Chapter 1MODEL CHART AND TECHNICAL SPECIFICATIONS 1.0 CM140/CM30/CM160/CM360 Model Chart ......................................................... 1-1 2.0 Technical Specifications ...................................................................................... 1-2 Chapter 2THEORY OF OPERATION 1.0 Introduction .......................................................................................................... 2-1 2.0 VHF (136-162MHz) Receiver............................................................................... 2-1 2.1 Receiver Front-End ........................................................................................ 2-1 2.2 Receiver Back End ......................................................................................... 2-2 3.0 VHF Transmitter Power Amplifier (136-162 MHz) ............................................... 2-2 3.1 First Power Controller Stage .......................................................................... 2-2 3.2 Power Controlled Driver Stage ....................................................................... 2-3 3.3 Final Stage ..................................................................................................... 2-3 3.4 Bi-Directional Coupler..................................................................................... 2-3 3.5 Antenna Switch............................................................................................... 2-3 3.6 Harmonic Filter ............................................................................................... 2-4 3.7 Power Control ................................................................................................. 2-4 4.0 VHF (136-162MHz) Frequency Synthesis ........................................................... 2-4 4.1 Reference Oscillator ....................................................................................... 2-4 4.2 Fractional-N Synthesizer ................................................................................ 2-5 4.3 Voltage Controlled Oscillator (VCO) ............................................................... 2-6 4.4 Synthesizer Operation .................................................................................... 2-7 5.0 Controller Theory of Operation ............................................................................ 2-8 5.1 Radio Power Distribution ................................................................................ 2-8 5.2 Protection Devices........................................................................................ 2-10 5.3 Automatic On/Off .......................................................................................... 2-10 5.4 Microprocessor Clock Synthesiser ............................................................... 2-11 5.5 Serial Peripheral Interface (SPI) ................................................................... 2-12 5.6 SBEP Serial Interface ................................................................................... 2-12 5.7 General Purpose Input/Output...................................................................... 2-12 5.8 Normal Microprocessor Operation................................................................ 2-13 5.9 Static Random Access Memory (SRAM)...................................................... 2-14 6.0 Control Board Audio and Signalling Circuits ...................................................... 2-14 6.1 Audio Signalling Filter IC and Compander (ASFIC CMP) ............................ 2-14 7.0 Transmit Audio Circuits ...................................................................................... 2-15 7.1 Microphone Input Path ................................................................................. 2-15 7.2 PTT Sensing and TX Audio Processing ....................................................... 2-16 8.0 Transmit Signalling Circuits ............................................................................... 2-17 8.1 Sub-Audio Data (PL/DPL) ............................................................................ 2-17 8.2 High Speed Data .......................................................................................... 2-18
iv 8.3 Dual Tone Multiple Frequency (DTMF) Data ............................................... 2-18 9.0 Receive Audio Circuits....................................................................................... 2-19 9.1 Squelch Detect ............................................................................................. 2-19 9.2 Audio Processing and Digital Volume Control.............................................. 2-20 9.3 Audio Amplification Speaker (+) Speaker (-) ................................................ 2-20 9.4 Handset Audio .............................................................................................. 2-21 9.5 Filtered Audio and Flat Audio ....................................................................... 2-21 10.0 Receive Signalling Circuits ................................................................................ 2-21 10.1 Sub-Audio Data (PL/DPL) and High Speed Data Decoder .......................... 2-21 10.2 Alert Tone Circuits ........................................................................................ 2-22 Chapter 3TROUBLESHOOTING CHARTS 1.0 Troubleshooting Flow Chart for Receiver RF (Sheet 1 of 2)................................ 3-2 1.1 Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ................................ 3-3 2.0 Troubleshooting Flow Chart for 25W Transmitter (Sheet 1 of 3) ......................... 3-4 2.1 Troubleshooting Flow Chart for 25W Transmitter (Sheet 2 of 3).................... 3-5 2.2 Troubleshooting Flow Chart for 25W Transmitter (Sheet 3 of 3).................... 3-6 3.0 Troubleshooting Flow Chart for Synthesizer........................................................ 3-7 4.0 Troubleshooting Flow Chart for VCO ................................................................... 3-8 5.0 Troubleshooting Flow Chart for DC Supply (1 of 2) ............................................. 3-9 5.1 Troubleshooting Flow Chart for DC Supply (2 of 2) ..................................... 3-10 Chapter 4VHF1 PCB/ SCHEMATICS/ PARTS LISTS 1.0 Allocation of Schematics and Circuit Boards ....................................................... 4-1 1.1 VHF1 and Controller Circuits.......................................................................... 4-1 2.0 VHF 1-25W Band 1 PCB 8486672Z01 / Schematics .......................................... 4-3 2.1 VHF1 PCB 8486672Z01 Parts List 1-25W ................................................... 4-19
Chapter 1 MODEL CHART AND TECHNICAL SPECIFICATIONS 1.0 Model Chart (VHF1 136-162 MHz) CM Series VHF1 136-162MHz Model Description MDM50JNC9AA2_NCM140 136-162 MHz 1-25W 8-Ch MDM50JNF9AA2_N CM160 136-162 MHz 1-25W 64-Ch MDM50JNF9AN2_NCM360 136-162 MHz 1-25W 100-Ch Item Description X PMUD1936_ S. Tanapa VHF1 25W 8 Ch BNC XPMUD1940_S. Tanapa VHF1 25W 64 Ch BNC X PMUD1941_ S. Tanapa VHF1 25W 100 Ch BNC XFCN6288_Control Head X X FCN5523_ Control Head XXXHKN4137_Battery Power Cable XX XRMN5018_ HMN3596_Mag One Microphone Compact Microphone XXXGLN7324_Low Profile Trunnion X X X 6866546D02_ RTTE Leaflet XXX6866537D37_Safety Leaflet X PMUD1952AS Servicing Kit CM140 XPMUD1956ASServicing Kit CM160 X PMUD1957AS Servicing Kit CM360 X = Indicates one of each is required
1-2 MODEL CHART AND TECHNICAL SPECIFICATIONS 2.0 Technical Specifications Data is specified for +25°C unless otherwise stated. General Specification VHF1 Frequency Range:136-162 MHz Frequency Stability (-30°C to +60°C, 25°C Ref.)±2.5 PPM Channel Capacity:CM140 - 8 CM340 - 10 CM160 - 64 CM360 - 100 Channel Spacing: 12.5/20/25 kHz Power Supply:13.8 Vdc (11 Vdc - 16.6 Vdc) negative Vehicle ground Dimensions (L x W x H) 4.65” X 6.67” X 1.73” (118mm X 169.5mm X 44mm) Weight2.22 lbs (1.01 kg) FCC Description ABZ99FT3048 Operating Temperature-30 to 60° C (Display only -20°C to 60°C) Storage Temperature -40 to 85° C Thermal Shock-40 to 80° C High Humidity 95% RH @ 50° C for 8 hrs ESD15KV air discharge Packing Test Impact Test
Technical Specifications1-3 Transmitter Specification VHF1 Power Output1-25W Conducted/Radiated Emissions:-36 dBm < 1 GHz -30 dBm > 1 GHz Audio Response: (from 6 dB/ oct. Pre-Emphasis, 300 to 3000Hz) +1, -3dB Tx Audio Distortion < 3% Modulation Limiting:±2.5 kHz @ 12.5 kHz ±4.0 kHz @ 20 kHz ±5.0 kHz @ 25 kHz FM Hum and Noise: -40 [email protected] kHz -45 dB@25 kHz Receiver Specification VHF1 Sensitivity (12 dB SINAD):0.35 µV @ 12.5 kHz 0.3 µV @ 25 kHz Intermodulation: 65 [email protected] kHz 75 dB@25 kHz Adjacent Channel Selectivity:65 dB @ 12.5 kHz 75 dB @ 25 kHz Spurious Response 75 dB Rated Audio Power4 W (typ.) Internal 7.5 W @ 5 % External Audio Distortion < 5 % Hum and Noise:-40 dB @ 12.5 kHz -45 dB @ 25 kHz Audio Response +1, -3dB Conducted Spurious Emission per FCC Part 15:-57 dBm 1 Ghz Specifications subject to change without notice. All electrical specifications and methods refer to EIA/TIA 603 standards.
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Chapter 2 THEORY OF OPERATION 1.0 Introduction This Chapter provides a detailed theory of operation for the VHF circuits in the radio. Details of the theory of operation and trouble shooting for the associated Controller circuits are included in this Section of the manual. 2.0 VHF (136-162MHz) Receiver 2.1 Receiver Front-End The received signal is applied to the radio’s antenna input connector and routed through the harmonic filter and antenna switch. The insertion loss of the harmonic filter/antenna switch is less than 1 dB. The signal is routed to the first filter (4-pole), which has an insertion loss of 2 dB typically. The output of the filter is matched to the base of the LNA (Q303) that provides a 16 dB gain and a noise figure of better than 2 dB. Current source Q301 is used to maintain the collector current of Q303. Diode CR301 protects Q303 by clamping excessive input signals. Q303 output is applied to the second filter (3-pole) which has an insertion loss of 2 dB. In Distance mode, Q304 turns on and causes D305 to conduct, thus bypassing C322 and R337. In Local mode, the signal is routed through C322 and R337, thus inserting 7 dB attenuation. Since the attenuator is located after the RF amplifier, the receiver sensitivity is reduced only by 6 dB, while the overall third order input intercept is raised. The first mixer is a passive, double-balanced type, consisting of T300, T301 and U302. This mixer provides all of the necessary rejection of the half-IF spurious response. High-side injection at +15 dBm is delivered to the first mixer. The mixer output is then connected to a duplex network which matches its output to the XTAL filter input (FL300) at the IF frequency of 44.85 MHz. The duplex network terminates into a 50 ohm resistor (R340) at all other frequencies. Figure 2-1 VHF Receiver Block Diagram Mixer Xtal Filter Controller Front Filter Antenna First LO 2nd LO Xtal Osc IF AmpSecond Filter4- Pole 25kHzFilter 12.5kHzFilter Phase Shift Element IFIC LNA 25kHzFilter 12.5kHzFilter
2-2THEORY OF OPERATION 2.2 Receiver Back End The IF signal from the crystal filter enters the IF amplifier which provides 20 dB of gain and feeds the IF IC at pin 1. The first IF signal at 44.85 MHz mixes with the second local oscillator (LO) at 44.395 MHz to produce the second IF at 455 kHz. The second LO uses the external crystal Y301. The second IF signal is amplified and filtered by two external ceramic filters (FL303/FL302 for 12.5KHz channel spacing and FL304/FL301 for 25KHz channel spacing). The IF IC demodulates the signal by means of a quadrature detector and feeds the detected audio (via pin 7) to the audio processing circuits. At IF IC pin 5, an RSSI signal is available with a dynamic range of 70 dB. 3.0 VHF Transmitter Power Amplifier (136-162 MHz) The radio’s 25W PA is a three-stage amplifier used to amplify the output from the TX_INJ to the antenna port. All three stages utilize LDMOS technology. The gain of the first stage (U101)and the second stage (Q105) is adjustable and is controlled by pin 7 of U103-2 via U103-3 and U102-1. It is followed by an LDMOS final stage Q100. Figure 2-2 VHF Transmitter Block Diagram Devices U101, Q105 and Q100 are surface mounted. Two screws with Belleville washers provide direct pressure ensuring good thermal contact between both the driver and final stage, and the chassis. 3.1 First Power Controller Stage The first stage (U101) is a 20dB gain integrated circuit containing two LDMOS FET amplifier stages. It amplifies the RF signal from the VCO (TX_INJ). The output power of stage U101 is controlled by a DC voltage applied to pin 1 from the op-amp U103-3, pin 8. The control voltage simultaneously varies the bias of two FET stages within U101. This biasing point determines the overall gain of U101 and therefore its output drive level to Q105, which in turn controls the output power of the PA. Loop Pin Diode Antenna Switch RF JackAntenna Harmonic Filter CouplerPA-FinalStag e From VCO (TX_INJ) ControlledStage Bias Temperature Sense SPI BUSASFIC_CMP PA PWR SET PA Driver Controller U103-2Forward