Motorola Xts1500 Xts2500 Basic 6881094c09 B Manual
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3 Basic Maintenance 2 Introduction to This SectionThis section of the manual describes preventive maintenance and handling precautions. Each of these topics provides information vital to the successful operation and maintenance of your radio. Preventive MaintenanceASTRO Digital XTS 2500 radios do not require a scheduled preventive maintenance program; however, periodic visual inspection and cleaning is recommended. InspectionCheck that the external surfaces of the radio are clean, and that all external controls and switches are functional. A detailed inspection of the interior electronic circuitry is not needed. CleaningThe following procedures describe the recommended cleaning agents and the methods to be used when cleaning the external surfaces of the radio. External surfaces include the housing assembly and battery case. These surfaces should be cleaned whenever a periodic visual inspection reveals the presence of smudges, grease, and/or grime. The only recommended agent for cleaning the external radio surfaces is a 0.5% solution of a mild dishwashing detergent, such as JOY ®, in water. Cleaning External Plastic SurfacesThe detergent-water solution should be applied sparingly with a stiff, non-metallic, short- bristled brush to work all loose dirt away from the radio. A soft, absorbent, lintless cloth or tissue should be used to remove the solution and dry the radio. Make sure that no water remains entrapped near the connectors, cracks, or crevices. The effects of certain chemicals and their vapors can have harmful results on certain plastics. Aerosol sprays, tuner cleaners, and other chemicals should be avoided. ! C a u t i o n
Basic Maintenance 4 Handling PrecautionsComplementary metal-oxide semiconductor (CMOS) devices, and other high-technology devices, are used in this family of radios. While these devices have many attributes, their characteristics make them susceptible to damage by electrostatic discharge (ESD) or high- voltage charges. Damage can be latent, resulting in failures occurring weeks or months later. Therefore, special precautions must be taken to prevent device damage during disassembly, troubleshooting, and repair. Handling precautions are mandatory for this radio, and are especially important in low-humidity conditions. Never heat the RF PA above 210°C while performing repair or rework procedures to maintain its integrity. Utilizing a Chipmaster (R1319 or R1321) top-side set point of 215°C and a Dragon (R1427) bottom-side pre-heat set point of 180°C has proven to satisfy this condition during the rework of the RF PA (note: the RF PA temperature does not reach the Chipmaster’s internal set point temperature). All other parts on the transceiver board can be reworked with Chipmaster top-side heat alone.
5 Basic Theory of Operation 3 General OverviewThe ASTRO Digital XTS 2500 radio is a wideband, synthesized, fixed-tuned radio available in the 700/800 MHz bands. All XTS 2500 radios are capable of both analog operation (12.5 kHz or 25 kHz bandwidths) and digital ASTRO mode operation (12.5 kHz only). The ASTRO Digital XTS 2500 radio includes the following major assemblies (see Figure 1): •Main Board: contains the microcontrol unit (MCU) and its associated memory and memory management integrated circuit (IC), the audio power amplifier, and a switching regulator. The board also contains the digital signal processor (DSP) and its support IC and associated memories. It further contains all transmit, receive, and frequency generation circuitry, including the digital receiver back-end IC and the reference oscillator. Universal Flex: contains the universal connector, speaker, and microphone. Display (Models II and III only): a six-line, 12-character, liquid-crystal display (LCD). Keypad (Models II and III only): -Model II: a 3 x 2 keypad -Model III: a 3 x 6 keypad. Figure 1. XTS 2500 Overall Block Diagram Universal Flex (Side Connector, Controls, LEDs, Speaker, Microphone) Note: indicates 20 wires Main Board 7.5V Battery KeypadAntenna Display 3 2045 22 2013 J601 J650 J101 B500
Basic Theory of Operation 6 Analog Mode of Operation ReceivingWhen the radio is receiving (see Figure 2), the signal comes from the antenna connector to the radio board, passes through the RX/TX antenna switch and into the receiver front end. A 15dB step attenuator is included in the front end to provide additional protection against strong signals. The attenuator is controlled by a DSP based algorithm that continuously monitors signal strength. When the ON threshold is exceeded (approximately -95dBm), the attenuator is activated via a DAC in the PCIC by the host. The attenuator remains activated until the signal drops below the OFF threshold (approximately -115dBm including the 15dB attenuation). Hysterisis and timer functions are included in the algorithm to enhance performance. The algorithm controlling the attenuator is enabled via the CPS for each personality. When the algorithm is disabled, the attenuator is essentially a short circuit from input to output.The signal is then filtered, amplified, and mixed with the first local- oscillator signal generated by the voltage-controlled oscillator (VCO). The resulting intermediate frequency (IF) signal is fed to the IF circuitry, where it is again filtered and amplified. This amplified signal passes to the digital back-end IC, where it is mixed with the second local oscillator to create the second IF at 450 kHz. It is then converted to a digital bit stream and mixed a third time to produce a baseband signal. This signal is passed to the VOCON circuitry through a current-driven differential output. In the VOCON circuitry, the digital-signal processor (DSP) support IC digitally filters and discriminates the signal, and passes it to the DSP. The DSP decodes the information in the signal and identifies the appropriate destination for it. For a voice signal, the DSP routes the digital voice data to the CODEC for conversion to an analog signal. The CODEC then presents the signal to the audio power amplifier, which drives the speaker. For signalling information, the DSP decodes the message and pass it to the microcontrol unit. TransmittingWhen the radio is transmitting (see Figure 3), microphone audio is passed through gain stages to the CODEC where the signal is digitized. The CODEC passes digital data to the DSP where pre-emphasis and low-pass (splatter) filtering are done. The DSP passes this signal to a digital-to-analog (D/A) converter where it is reconverted into an analog signal and scaled for application to the voltage-controlled oscillator as a modulation signal.Figure 2. Receiver Block Diagram RF InputRX Front End Harmonic Filter ADC LOCKORX_SSI_ DATA to VOCON Board XTAL Filter ABACUS III - RX Back End Antenna SwitchTuneable PreslectorRF Amp AttenuatorTuneable Preselector Filter 1st Mixer 1st LO 3 MAEPF-27278-O
Basic Theory of Operation 7 Transmitted signalling information is accepted by the DSP from the microcontrol unit, coded appropriately, and passed to the D/A converter, which handles it the same as a voice signal. Modulation information is passed to the synthesizer along the modulation line. A modulated carrier is provided to the RF PA, which transmits the signal under dynamic power control. ASTRO Mode of OperationIn the ASTRO mode (digital mode) of operation, the transmitted or received signal is limited to a discrete set of deviation levels, instead of continuously varying. The receiver handles an ASTRO-mode signal identically to an analog-mode signal up to the point where the DSP decodes the received data. In the ASTRO receive mode, the DSP uses a specifically defined algorithm to recover information. In the ASTRO transmit mode, microphone audio is processed identically to an analog mode with the exception of the algorithm the DSP uses to encode the information. This algorithm will result in deviation levels that are limited to discrete levels. RF Basic Theory of OperationThe receiver front end consists of a preselector, an RF amplifier, a second preselector, and a mixer. Both preselectors are varactor-tuned, two-pole filters, controlled by the microcontroller unit through the D/A IC. The RF amplifier is a dual-gate, gallium-arsenide- based IC. The mixer is a double-balanced, active mixer, coupled by transformers. Injection is provided by the VCO through an injection filter. See Table 2 for local oscillator (LO) and first IF information. The frequency generation function is performed by three ICs and associated circuitry. The reference oscillator provides a frequency standard to the synthesizer/prescaler IC, which controls the VCOB IC. The VCOB IC actually generates the first LO and transmit-injection Figure 3. RF Block Diagram (Power and Control Omitted) Reference Oscillator FracN U201 MOD INLoop Filter LPF FL200EPIC Y200 DAC U203VCOVCOBIC U250 VCO Crystal Filter FL3Mixer U1 2ND LO Sample Clk To RX_SSI From TX_SSI Preselector Filter FL2Attenuator PCIC U102Power Module Q101 TX Buffer Q216TX Driver Amplifier U101 RF Power Detector D103Directional Coupler U106 Antenna Switch Preselector Filter FL1 RX LNA Q1To Antenna Harmonic Filter ABACUS III U401 MAEPF-27322-O VCO 3 3 Table 2. Local Oscillator and First IF Frequencies 700 MHz800 MHz LO Frequency Range -- -- First IF Frequency 109.65 MHz 109.65 MHz
Basic Theory of Operation 8 signals and buffers them to the required power level. The synthesizer/prescaler circuit module incorporates frequency-division and comparison circuitry to keep the VCO signals stable. The synthesizer/prescaler IC is controlled by the microcontrol unit through a serial bus. The receiver back end consists of a two-pole crystal filter, an IF amplifier, a second two- pole crystal filter, and the digital back-end IC. The two-pole filters are wide enough to accommodate 4 kHz modulation. Final IF filtering is done digitally in the DSP. The digital back-end IC consists of an amplifier, the second mixer, an IF analog-to-digital converter, a baseband down-converter, and a 2.4 MHz synthesis circuit to provide a clock to the DSP-support IC on the VOCON circuitry. The second LO is generated by discrete components external to the IC. The output of the digital back-end IC is a digital bit stream that is current driven on a differential pair for a reduction in noise generation. The transmitter consists of an RF driver IC that gets an injection signal from the VCO and a final-stage power amplifier. Transmit power is controlled by a power-control IC that monitors the output of a directional coupler and adjusts PA control voltages correspondingly. The signal passes through a RX/TX switch that uses PIN diodes to automatically provide an appropriate interface to transmit or receive signals. Antenna selection is done mechanically in the control top. VOCON Basic Theory of OperationThe vocoder and controller (VOCON) circuitry contains the radio’s microcontrol unit with its memory and support circuits, the DSP, its memory devices, and the DSP-support IC, voltage regulators, audio, and power control circuits. Connected to the VOCON circuitry are the display board, RF circuitry, keypad board, and controls/universal flex. The microcontrol unit controls receive/transmit frequencies, power levels, display, and other radio functions, using either direct logic control or serial communications paths to the devices.The microcontrol unit executes a stored program located in the FLASH ROM. Data is transferred to and from memory by the microcontrol unit data bus. The memory location from which data is read, or to which data is written, is selected by the address lines. The DSP-support IC is supplied with a 16.8 MHz clock from the RF circuitry. Both the DSP and the microprocessor have their clocks generated by the DSP-support IC. They can both be adjusted so that the harmonics do not cause interference with the radio’s receive channel. The regulator and power-control circuits include 3.3-volt analog, 3.3-volt digital, and 5- volt regulators. The audio PA is sourced from 7.5V. The regulator’s power-down mode is controlled by the microcontrol unit, which senses the position of the on/off switch. The 5- volt regulator has an error pin for low-voltage resets. The DSP performs signalling and voice encoding and decoding, as well as audio filtering and volume control. This IC performs Private-Line®/Digital Private Line™ (PL/DPL) encode and alert-tone generation. The IC transmits pre-emphasis on analog signals and applies a low-pass (splatter) filter to all transmitted signals. It requires a clock on the EXTAL pin. An 8 kHz interrupt signal generated by the DSP-support IC is also required for functionality. It is programmed using parallel programming from the microcontrol unit. The audio CODEC performs analog-to-digital (A/D), and digital-to-analog conversions on audio signals. The DSP controls squelch, deviation, and executes receiver and transmitter filtering. The DSP-support IC receives a 2.4 MHz clock, and also receives data, which it formats for the DSP.
9 Recommended Test Equipment and Service Aids 4 Recommended Test EquipmentThe list of equipment contained in Table 3 includes all of the standard test equipment required for servicing two-way portable radios, as well as several unique items designed specifically for servicing this family of radios. The “Characteristics” column is included so that equivalent equipment may be substituted; however, when no information is provided in this column, the specific Motorola model listed is either a unique item or no substitution is recommended. Table 3. Recommended Test Equipment Motorola Model NumberDescriptionCharacteristicsApplication R2600 Series Communications System AnalyzerThis monitor will substitute for items with an asterisk (*).Frequency/deviation meter and signal generator for wide-range troubleshooting and alignment. Fluke 8012 Digital Multimeter Recommended for ac/dc voltage and current measurements R1150_* Code Synthesizer Injection of audio and digital signalling codes R1377_* AC Voltmeter 1mV to 300V, 10-Megohm input impedanceAudio voltage measurements R1094_ Dual-Trace Oscilloscope20 MHz bandwidth 5mV to 5V/ divisionWaveform measurements S1350_* ST1213_ (VHF)* ST1223_ (UHF)*Wattmeter Plug-In Element RF Dummy Load50-ohm, ±5% accuracy 10 watts, maximum 0-1000 MHz, 300WTransmitter power output measurements R1065_ Load Resistor 10-watt Broadband For use with wattmeter S1339_ RF Millivolt Meter 100µ V to 3V RF RF-level measurements R1013_* SINAD Meter Receiver sensitivity measurements S1347_ or S1348_ (programmable)DC Power Supply 0-20Vdc, 0-5 Amps current limitedBench supply for 7.5Vdc *The R2600 Series monitor will substitute for these items.
Recommended Test Equipment and Service Aids 10 Service Aids Refer to Table 4., “Service Aids,” for a listing and description of the service aids designed specifically for servicing this family of radios. These kits and/or parts are available from the Motorola Parts Division offices listed in the “Replacement Parts Ordering” section located on the inside back cover of this manual. 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. NOTE:The Radio Interface Box (RIB), Smart Radio Interface Box (SRIB), and any cables that connect with those boxes are incompatible with the XTS 2500 radio and should NOT be used. Field Programming EquipmentThis family of radios can be aligned and programmed in the field. This requires specific equipment and special instructions. Refer to the applicable “CPS On-line Help” for complete field programming information.Table 4. Service Aids Motorola Part NumberDescriptionApplication 6685666D01 Chassis Opener Tool Used to remove radio knobs and to separate chassis from Front Cover. RKN-4106_ RS232/Radio/Test Set Cable Connects radio to RLN4460 Test Box and to RS232 computer connector (DB9). 0180305G54 Battery Eliminator Interconnects radio to power supply. RLN-4460 Portable Test Set Enables connection to the universal connector. Allows switching for radio testing. RVN-4181_ Customer Programming SoftwareCustomer Programming Software (CPS)/Tuner on one CD-ROM. 58-80348B33 SMA to BNC Adaptor Adapts radio’s antenna port to BNC cabling of test equipment. RKN4105 USB/Radio/Test Set Cable Connects radio to RLN4460 test box and to USB computer connector. 8180384M37 Test Fixture Provides for troubleshooting the radio board when the back casting is removed.
11 Performance Checks 5 Introduction to This SectionThis section covers performance checks used to verify that the radio meets published specifications. The recommended test equipment listed in the previous section approaches the accuracy of the manufacturing equipment, with a few exceptions. Accuracy of the equipment must be maintained in compliance with the manufacturer’s recommended calibration schedule. Checks should be performed if radio performance degradation is suspected. SetupSupply voltage can be connected from the battery eliminator. The equipment required for alignment procedures is connected as shown in the “Radio Alignment Test Setup” diagram (Figure 4). Figure 4. Radio Alignment Test Setup BNC COMPUTERAUDIO GENERATOR SINAD METER AC VOLTMETER TX RX 30 dB PAD 30 dB PAD RF GENERATORSYSTEM ANALYZER OR COUNTER WATTMETER BATTERY ELIMINATOR 0180305G54 TRANSMIT RECEIVE RADIO PROGRAM/TEST CABLE RKN4106 AUDIO IN SET TO APPROX. 450mV FOR Tx MEASURE 80mV FOR Tx SMA-BNC 58-80348B33 TEST SET RLN-4460
Performance Checks 12 Initial equipment control settings should be as indicated in the Table 5, and should hold for all alignment procedures except as noted. Display Radio Test Mode Entering Display Radio Test Mode1. Turn the radio on. 2. Within 10 seconds after “Self Test” is complete, press Side button 3 five times in succession. 3. The radio will show a series of displays that will give information regarding various version numbers and subscriber specific information. The displays are described in Table 6. NOTE:All displays are temporary and will disappear without any user intervention. If information is longer than the physical length of the radio’s display, the information will wrap around to the next display. After the last display, “RF TEST” will be displayed. For non-display radios, refer to the CPS Radio Information Screen.Table 5. Initial Equipment Control Settings System AnalyzerTe s t S e tPower Supply Monitor Mode: Pwr MonSpkr Set: AVo l t a g e : 7.5Vdc RF Attn: –70dBSpkr/Load: SpeakerDC On/Standby: Standby AM, CW, FM: FMPTT: OFF (center)Vo l t R a n g e : 10Vdc Oscope Source: Mod Oscope Horiz: 10mSec/Div Oscope Vert: 2.5 kHz/Div Oscope Trig: Auto Monitor Image: Hi Monitor BW: Nar Monitor Squelch: Mid CW Monitor Vol: 1/4 CWCurrent: 2.5Amps Table 6. Front-Panel Access Test-Mode Displays Name of DisplayDescriptionAppears “SERVICE” The literal string indicates the radio has entered test mode.Always. Host Software Version The version of host firmware. Always. DSP Software Version The version of DSP firmware. Always. Model Number The radio’s model number as programmed in the codeplug.Always. Serial Number The radio’s serial number as programmed in the codeplug.Always. ROM Size The memory capacity of the host FLASH part. Always. FLASHcode The FLASH codes as programmed in the codeplug. Always.