Motorola Astro Digital Mobile Radio Xtl5000 Basic 6881096c73 O Manual

							6881096C73-OJune 11, 2003
Basic Theory of Operation: Control Head Assembly 3-7
3.8.2 Display (W9 Control Head)
The W9 control-head assembly has an 11-character, alphanumeric, vacuum fluorescent display. It 
needs three separate voltages to operate: the cathode needs 35 V to accelerate electrons to the 
anode; the grid needs 40 V to totally shut off current flow; the filament needs 3.8 Vrms at 80 mA. 
These voltages are obtained from the transformer on the display controller board.
3.8.3 Vacuum Fluorescent (VF) Display Driver
This VF display driver receives ASCII data from the controller section of the main board, decodes it 
into display data, and then scans the display with the data. Once properly loaded into the display, 
data is refreshed without any further processor action. The display driver is periodically reset by the 
actions of transistors that watch the clock line from the microprocessor to the display driver. When 
the clock line is held low for more than 600 ms, the display driver resets and new display data 
follows.
3.8.4 Vacuum Fluorescent (VF) Voltage Source (W9)
Voltage for the VF display is generated by a fixed frequency, variable-duty cycle-driven, flyback 
voltage converter. An emitter-coupled astable multivibrator runs at approximately 150 kHz. The 
square-wave output from this circuit is integrated to form a triangle that is applied to the non-inverting 
input of half an IC.
During start up, the inverting input is biased at 3.7 V. A transistor is on while the non-inverting input 
voltage is below 3.7 V. This allows current to flow in a transformer, building a magnetic field. When 
the triangle wave exceeds 3.7 V, the transistor turns off and the magnetic field collapses, inducing 
negative current in the transformer.
This current flow charges two capacitors. As the voltage on one of the capacitors increases beyond 
35 V, a diode begins to conduct, pulling the integrated circuit’s inverting input below 3.7 V. This 
decreases the cycle time to produce the 35 V. The 41-volt supply is not regulated, but it tracks the 
35-volt supply.
Similarly, the AC supply for VF filament is not regulated, but is controlled to within one volt by an 
inductor on the display board.
3.8.5 Controls and Indicators
The control head assembly processes all the keypad (button) inputs and visual indicators through 
the microprocessor. Some of the buttons double as function keys for radio options. All buttons are 
backlit to allow operation in low light. Refer to 
Chapter 1. Introduction (“1.4 Control Head 
Descriptions” on page 1-2
) for functional descriptions of each control switch, button, or indicator.
3.8.6 Status LEDs
These LEDs are driven by the display driver as though they were decimal points on the VF display. 
Level shifting transistors are required for this since the display driver uses 39 Vdc for control signals.
3.8.7 Backlight LEDs
The microprocessor operates the backlight LEDs. A transistor supplies base current to the individual 
LED driver transistors. The driver transistors act as constant current sources to the LEDs. Some 
backlight LEDs are connected to a thermistor. This circuit allows more current to flow through these 
LEDs at room temperature and reduces current as the temperature rises. 
						

							June 11, 20036881096C73-O
3-8Basic Theory of Operation: Control Head Assembly
3.8.8 Vehicle Interface Port (VIP)
3.8.8.1  Remote-Mount
The VIPs allow the control head to operate outside circuits and to receive inputs from outside the 
control head. There are three VIP outputs that are used for the W9 control head and two VIP outputs 
for the W3, W4, W%, and W7 control heads. There are also three VIP inputs that accept inputs from 
switches. See the cable kit section for typical connections of VIP input switches and VIP output 
relays.
The VIP output pins are located on the back of the control head below the area labeled “VIP.” These 
connections are used to control relays. One end of the relay should be connected to switched B+, 
while the other side is connected to a software-controlled on/off switch inside the control head. The 
relay can be normally on or normally off depending on how the VIP outputs are configured. The 
function of these VIP outputs can be defined by field programming the radio. Typical applications for 
VIP outputs are external horn/lights alarm and horn ring transfer relay control.
3.8.8.2  Dash-Mount
The VIP outputs are driven by a serial-to-parallel shift register. The output transistors are capable of 
sourcing 300mA current. Primarily, these transistors control external relays. The relay is connected 
between the collector and switched B+.
Each VIP input transistor is connected to a dedicated input port through transistors used for input 
protection. These VIP inputs are connected to ground with either normally open or normally closed 
switches.
3.8.9 Control-Head Power Supplies
This section describes the control-head power supply operation.
3.8.9.1  W3 Control Head
W3 control heads supply power to the switched B (SWB+) line through a P-channel power MOSFET 
from the HLN6885 interface board only.
3.8.9.2  W4 Control Head
For W4 control heads, power to SWB+ is supplied by a mechanical switch on the volume control 
knob. If the ignition line option is used, power to the switch comes directly from the ignition wire 
instead of A+.
3.8.9.3  W5, W7, W9 Control Heads
SWB+ is supplied from A+ through an N-channel power MOSFET driven by the Serial Input/Output 
(SIO) IC in the legacy control heads. SWB+ supplies power to the accessories, the VF display, the 5-
volt regulator, and the power-control line for the main board for all other voltage regulators on the 
main board. The SIO IC monitors the condition of the power switch and the ignition switch to 
determine the on/off state of the radio.
3.8.10 Ignition Sense Circuits
A transistor senses the vehicle ignition’s state, disabling the radio when the ignition is off. For 
negative-ground systems, the orange lead for remote-mount radios and the red lead for dash-mount 
radios is typically connected to the fuse box (+12 V). 
						

							6881096C73-OJune 11, 2003
Basic Theory of Operation: Radio-Frequency Power Amplifier (RF PA) and Output Network (ON) 3-9
3.9 Radio-Frequency Power Amplifier (RF PA) and Output Network 
(ON)
The RF PA is a three-stage power amplifier consisting of discrete LDMOS transistors:
 Controlled stage
 Driver stage
 Final stage
The RF PA is followed by the ON section consisting of discrete circuitry with the following functions:
 Antenna switch
 Harmonic Filter
 Power Detector
3.9.1 Gain Stages
The controlled stage consists of a two-stage, integrated amplifier with external matching which 
amplifies the input signal from the VCO buffer and provides drive to the driver stage. Power is 
controlled via gate bias to both internal stages and drain bias is supplied via K9.1V. The drive stage 
has a fixed gate bias and drain bias is supplied by the A+ (battery) voltage. The driver stage drives 
the final stage consisting of two transistors operating in parallel. Both devices have separate, fixed 
gate biases and their drain biases are supplied by the A+ voltage. The output of the final stage feeds 
the antenna switch which routes the RF PA to the harmonic filter/power detector/antenna and 
isolates the RX front-end in transmit mode. Antenna switch routes antenna/power detector/harmonic 
filter to RX and isolates TX in RX mode. Mode is determined via K9.1V. The harmonic filter is a low-
pass filter that attenuates harmonics generated by the RF PA in transmit mode and provides 
additional receive selectivity in receive mode.
3.9.2 Power Control
Power is regulated by an automatic-level control (ALC) circuit. The transmitter ALC consists of a 
distributed power detector with a detection diode, buffer/amplifier, digital-to-analog converter (DAC), 
and loop integrator. During transmission, the RF PA gain and output power is adjusted by a control 
voltage. The power detector senses incident power transferred to the antenna via a directional 
coupler whose signal is converted to a DC voltage by the detection diode. This DC voltage is 
buffered/amplified and then added to the DAC voltage which is then compared to a fixed voltage 
reference. The carrier power level is set tby adjusting the DAC voltage while monitoring the output 
power, which is saved tin radio memory.
3.9.3 Circuit Protection
RF PA final-stage drain current, RF PA final-stage temeperature, RF PA control voltage, and battery 
voltage are sensed by the power-control circuitry. If a fault condition is detected, the control voltage 
is reduced, which cuts back the output power to a level that is safe for the particular conditions.
3.9.4 DC Interconnect
The DC connector at the edge of the board carries the A+ supply for the entire board. This supply is 
routed directly to the controller and transmitter circuitry for both direct supply and regulating 
additional supplies. The radio chassis is grounded through the PCB screws and also via direct 
contact to the board. The control head receives the A+ supply through the 50-pin flex connector. 
						

							June 11, 20036881096C73-O
3-10Basic Theory of Operation: 700–800 Receiver Overview
3.10 700–800 Receiver Overview
The receiver circuits primary duties are to detect, filter, amplify, and demodulate RF signals in the 
presence of strong interfering noise and unintended signals. The receiver is broken down into the 
following blocks:
 Front-end (preselector and LNA)
Mixer
IF
 Back-end IC
3.10.1 Receiver Front-End 
The 700–800  MHz receiver front-end operates in two bands. The primary function of the front-end is 
to optimize image rejection and selectivity while providing the first conversion. The front-end uses 
ceramic filter technology and includes a wideband, monolithic amplifier. The first filter is a dual 
switched filter that reduces the image frequency response and limits some of the out-of-band 
interference. The second filter following the monolithic Low Noise Amplifier (LNA) provides additional 
image rejection.
3.10.2 Mixer
The signal is then fed to the monolithic Mixer IC where it is down converted to an IF of 73.35 MHz. 
The mixer is designed to provide low conversion loss and high intermodulation performance. The 
mixer is driven by the receiver injection buffer, a two-stage discrete IC design used with the receiver 
VCO to efficiently drive the mixer over a wide temperature range with minimum power variation. The 
injection buffer provides 15 dBm to the mixer. The VCO performs low-side injection for the 800 MHz 
band and high-side Injection for the 700 MHz band. The design maintains temperature stability, low 
insertion loss, and high out-of-band rejection.
3.10.3 IF Circuitry
The crystal filters provide IF selectivity and out-of-band signal protection to the back-end IC. Two 2-
pole crystal filters centered at 73.35 MHz that are isolated from one another by a stable, moderate 
gain amplifier are used to meet the receiver specifications for gain, close-in intermodulation 
rejection, adjacent-channel selectivity, and second-image rejection.
3.10.4 Abacus III Back-End
The output of the IF circuit is fed directly to the Abacus III digital back-end IC. The ABACUS III is an 
IC with a variable-bandwidth bandpass Sigma-Delta architecture. It is capable of down-converting 
analog as well as digital RF protocols into a baseband signal transmitted on the Synchronous Serial 
Interface (SSI) bus. The Abacus III IC converts the 73.35 MHz signal from the IF section down to 
2.25 MHz using a second LO frequency of 71.1 MHz or 75.6 MHz. The second LO VCO is tuned to 
71.1 MHz (low side) or 75.6 MHz (high side injection). The choice of frequency depends on known 
spurious interference related to the programmed received frequency. 
						

							6881096C73-OJune 11, 2003
Basic Theory of Operation: Frequency Generation Unit (FGU) 3-11
3.11 Frequency Generation Unit (FGU)
Figure 3-2.  Frequency Generation Unit Diagram
The frequency generation unit (FGU) (
Figure 3-2) is comprised of a fractional-N synthesizer IC, a 
16.8 MHz reference oscillator IC, two voltage-controlled oscillator (VCO) modules (receive and 
transmit, containing two VCOs each), VCO buffer/amplifier circuits, and associated circuitry.
The reference oscillator IC provides a frequency standard to the fractional-N synthesizer IC, the 
Abacus III digital back-end IC and to the controller section. The synthesizer turns on one of the four 
VCOs (determined by mode and band of operation) and tunes it to the receiver (RX) local oscillator 
(LO) or transmitter (TX) carrier frequency.
The voltage-controlled oscillator (VCO) module employs a Colpitts configuration with two bipolar 
stages in a common-base, common-collector configuration. The LC tank circuit’s capacitive portion 
consists of a varactor diode, coupling capacitor and a laser-trimmed capacitor for frequency 
adjustment. The inductive portion consists of microstrip transmission line resonators for TX VCO and 
coaxial resonators for RX VCO. Tuning is performed by the module manufacturer and is not field 
adjustable. The varactor changes the oscillator frequency when the DC voltage of the steering line 
changes. The output of the common base is coupled to the second transistor for impedance 
buffering, and its output is coupled to respective TX/RX buffer amplifiers. 
In TX mode, the transmitter VCO output is coupled to a three-stage buffer before being injected into 
the power amplifier (see 
“3.9 Radio-Frequency Power Amplifier (RF PA) and Output Network (ON)” 
on page 3-9
). In RX mode, the receiver VCO output is buffered and amplified with a two-stage 
transistor/microwave monolithic IC (MMIC) circuit. The output of the first-stage transistor is split into 
two paths. One path feeds back to the synthesizer prescaler; the other path is injected into the 
second-stage MMIC. The output of the MMIC provides the proper signal level for the LO port of the 
RX front-end mixer (see 
“3.10 700–800 Receiver Overview” on page 3-10).
The super filter supplies the voltage to the first two stages of the TX buffer and to the first-stage 
transistor of the RX buffer/amplifier. The voltage for the third stage of the TX buffer is supplied by a 
keyed 9.1 V source to conserve current drain while the radio is receiving. The second stage MMIC of 
the RX buffer/amplifier is supplied by a 9.3 V regulator.
Loop Filter Adapt
Buffer
Controller
Rx BE Dual Rx VCO
Dual Tx VCO 9.3 V
9.1 V9.3 V
3 V
LV Frac-N
Synthesizer Dual
Charge
Pump
TCXO
16.8 MHz
Transmit
Modulation
AUX-
Tx/Rx SelectPreScaler
INSPI
Super Filter
Steering
Line Voltage
Tx
Buffer Rx FERx
Buffer
RFPA
+ -+ -
+ -
+ -
8.2 V Out
MAEPF-27588-A 
						

							June 11, 20036881096C73-O
3-12Basic Theory of Operation: Frequency Generation Unit (FGU)
Notes 
						

							Chapter 4 Test Equipment, Service Aids, and Tools
4.1 Recommended Test Equipment
The list of equipment contained in Table 4-1 includes most of the standard test equipment required 
for servicing Motorola mobile radios, as well as several unique items designed specifically for 
servicing this family of radios. The Characteristics column is included so that equivalent equipment 
can 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 4-2 contains a listing of the plug-in elements that are available for the BIRD wattmeters listed 
in the Table 4-1.Table 4-1.  Recommended Motorola Test Equipment
Motorola
Model NumberDescriptionCharacteristicsApplication
R-1439 or
R-1440
(See Table 4-2 for 
plug-in elements)BIRD Wattmeter
BIRD WattmeterPower range: 100 mW to 100W, 
2 MHz to 1GHz,
UHF-F connector
Power range: 100 mW to 100W, 
2 MHz to 1GHz,
N-female connectorTransmitter power 
measurements
R-1611 Dual-Channel 100 MHz 
Oscilloscope (Agilent)Two-channel, 100MHz 
bandwidth, 200 Msample rate/
sec., 2MB memory/channelWaveform measurements
R-2670
(with options, as 
applicable)System Analyzer This item will substitute for items 
with an asterisk (*).Frequency/deviation meter and 
signal generator for wide-range 
troubleshooting and alignment
Table 4-2.  Wattmeter Plug-In Elements
Power25-60 MHz50-125 MHz100-250 MHz200-500 MHz400-1000 MHz
5W --- 0180305F29 0180305F38 0180305F46
10W --- 0180305F22 0180305F30 0180305F47
25W 0180305F15 0180305F23 0180305F31 0180305F40 0180305F48
50W 0180305F16 0180305F24 0180305F32 0180305F41 0180305F49
100W 0180305F17 0180305F25 0180305F33 0180305F42 0180305F50
250W 0180305F18 0180305F26 0180305F34 0180305F43 0180305F51
500W 0180305F19 0180305F27 0180305F35 0180305F44 0180305F52
1000W 0180305F20 0180305F28 0180305F36 0180305F45 0180305F53 
						

							June 11, 20036881096C73-O
4-2Test Equipment, Service Aids, and Tools: Service Aids and Recommended Tools
Table 4-3 contains a listing of non-Motorola test equipment recommended for servicing mobile 
radios.
4.2 Service Aids and Recommended Tools
Refer to the tables in this section for a listing and description of the service aids and tools designed 
specifically for servicing this family of radios, as well as the more common tools required to 
disassemble and properly maintain the radio. These kits and/or parts are available from the Motorola 
parts division offices listed in Appendix A. Replacement Parts Ordering. Table 4-3.  Recommended Non-Motorola Test Equipment
Model NumberDescriptionApplication
1:1 Audio Transformer Audio measurement (audio PA must NOT be grounded)
Agilent 6552 Power Supply (0-20 V, 0-25 A) Mobile radio power supply
Agilent 8901 Modulation Analyzer Frequency, reference oscillator deviation and 
compensation measurements
Agilent 8903 Audio Analyzer Audio signal-level, SINAD, and distortion 
measurements
Fluke 45 Bench-Top Digital Multimeter AC/DC voltage and current measurements
Fluke 187 or 189 Handheld Digital Multimeter 
(True RMS, AC, AC+DC, dB)AC/DC voltage and current measurements
Fluke 190 Series Handheld Oscilloscope
(60-200 MHz Bandwidth, 2.5 GS/
sec, Built-in 500-Count True 
RMS Multimeter)Waveform measurements
HP E4430 Digital I/Q Modulation Signal 
SourceSignal source for transmit and receive digital tests
Weinschel 49 30 43 30 dB RF Attenuator For tests that require a modulation analyzer or 
wattmeter
Table 4-4.  Service Aids for XTL 5000 Board-Level Troubleshooting
Motorola
Part NumberDescriptionApplication
HKN6155 Programming Flash Cable Used with Tuner Software, CPS, and FLASHport
RVN4185 Customer Programming 
Software and Tuner SoftwareProgramming and radio alignment software on CD 
						

							6881096C73-OJune 11, 2003
Test Equipment, Service Aids, and Tools: Field Programming Equipment 4-3
4.3 Field Programming Equipment
The ASTRO family of radios can be aligned and programmed in the field. This requires specific 
equipment and special instructions. Refer to the online help in the Customer Programming Software 
(RVN4185).
4.3.1 XTL 5000 Field Programming
The XTL 5000 radios use a flash memory device to store information on frequencies, squelch codes, 
signaling codes, time-out timer durations, and other parameters.
The XTL 5000 radios can be programmed in the field any number of times without removing the flash 
memory from the radio.
4.3.1.1  Dash-Mounted Radios
To program and tune a dash-mounted XTL 5000 radio, the HKN6155 cable is connected to the radio 
via the microphone connector. The opposite end of the cable is connected to an IBM or IBM PC-
compatible computer. Another programming option is to connect a direct adapter cable to the radio’s 
rear accessory connector, J2, and connect the other end to the computer. (Please refer to the CPS 
Programming Installation Guide
—Motorola part number 6881095C44—for installation and setup 
procedures for the software.) Table 4-5.  Recommended Motorola Tools for Board-Level Troubleshooting
Motorola
Part NumberTools and Supplies
0180386A82 Anti-static grounding kit
8180384N71 Chassis eliminator
Control-head interconnect service cable
1185984D01 Electromagnetic Interference (EMI) metallic shielding tape, or  equivalent
0180320B16 Magnetic screwdriver set with bits
3085651A01 Mini-UHF to N-type adapter cable
6686119B01 Plastic scraping tool
6680163F01 Removal and insertion tool
RSX4043 Roto-Torq adjustable torque driver
Table 4-6.  Recommended Non-Motorola Tools for Board-Level Troubleshooting
Part NumberTools and Supplies
2.5 mm hex-key bit
Flat-blade screwdriver
Small, flat-blade screwdriver
MA-800G  Solder aid, (black stick), Hexacon Electric Co.
Torx® T10 and T20 drivers 
						

							June 11, 20036881096C73-O
4-4Test Equipment, Service Aids, and Tools: Field Programming Equipment
4.3.1.2  Remote-Mounted Radios
For remote-mounted radios, the cable is connected to the radio at the FLASHport connector, which 
is located on the remote faceplate of the transceiver. Another programming option is to use a direct 
adapter cable to connect the radio’s rear accessory connector, J2, to the computer. A third option is 
to use an ASTRO Packet Data cable to directly connect J6 on the remote faceplate to the computer. 
(Please refer to the CPS Programming Installation Guide
—Motorola part number 6881095C44—for 
installation and setup procedures for the software.)
Do not attempt to program via the remote control head. Be sure to disconnect any accessories that 
are connected to the radio’s microphone ports (including the microphones). Bias to these 
accessories could impair programming/tuning capability.
4.3.1.3  Field-Programming Items
Once the computer is connected to the radio, the prompts provided by the programming software 
can be followed. The following items, available through the Radio Products Services Division (except 
the computer), are required when programming XTL  5000 radios.
4.3.1.4  W3 Control-Head Error Message
For a radio equipped with a W3 control head, it is possible for the message FL01/90 to display while 
using the HKN6155 programming cable for tuner, CPS, or flash programming. Upon completion of 
the operation, a reset will clear the message. Powering on the radio before attaching the 
programming cable will decrease the occurrence of the 
FL01/90 message. Table 4-7.  XTL 5000 Radio Field-Programming Items
Ty p e  o r  P a r t  N u m b e rDescription
HKN6155 Programming Cable Used to connect radio directly to the computer.
Computer, IBM or IBM PC-
compatible
RVN4185 Customer 
Programming Software and 
Tuner SoftwareThis software enables you to program the radio’s features and 
align its parameters.