Motorola Mt1500 Basic 6881094c09 B Manual

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...

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,...

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...

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...

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...

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...

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...

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...

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...

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...