Motorola HT Series Operating and maintenance manual

MANUAL REVISION
12-26-03
®
© Motorola, Inc. 2003
8000 West Sunrise Boulevard
Fort Lauderdale, Florida 33322
*FMR2045A-2*
FMR-2045A-2
HT Series, MTX Series, PRO Series
Professional Series
Two-Way Portable Radios
Detailed Service Manual
6881088C46-E
REVISION CHANGE:
This manual revision contains theories of operation, schematics, board layouts, and troubleshooting
flowcharts for Professional Series radios with the following boards installed:
Use the information provided in this manual revision to supplement your Professional Series Two-Way
Portable Radios Detailed Service Manual, Motorola publication part number 6881088C46-E.
NOTE: Radio model charts and specifications information can be found in the appropriate Basic Service
Manual for the radio model you are servicing.
UHF (403 - 470 MHz) Main Board PCB No. 8486458Z02*
UHF Band 2 (450 - 527 MHz) Main Board PCB No. 8486686Z01*
VHF (136 - 174 MHz) Main Board PCB No. 8486473Z03*
* Indicates parts that cannot be ordered.
Publication Title Part number
HT1250•LS Professional Series Two-Way Radio
Basic Service Manual 6864110R15

December 26, 2003 2 FMR-2045A-2
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Table of Contents
REVISION CHANGE:................................................................................................................................. 1
Chapter 1 UHF Theory of Operation...............................................................................7
1.1 Transmitter........................................................................................................................................ 7
1.1.1 General................................................................................................................................ 7
1.1.2 Power Amplifier.................................................................................................................... 7
1.1.3 Antenna Switch.................................................................................................................... 8
1.1.4 Harmonic Filter .................................................................................................................... 8
1.1.5 Antenna Matching Network.................................................................................................. 8
1.1.6 Power Control Integrated Circuit (PCIC).............................................................................. 8
1.2 Receiver............................................................................................................................................ 9
1.2.1 Receiver Front-End.............................................................................................................. 9
1.2.2 Receiver Back-End............................................................................................................ 10
1.3 Frequency Generation Circuitry...................................................................................................... 10
1.4 Synthesizer..................................................................................................................................... 11
1.5 Voltage-Controlled Oscillator (VCO)............................................................................................... 12
Chapter 2 UHF Circuit Board Layouts, Schematic Diagrams and Parts List............ 15
2.1 Notes for All Schematics and Circuit Boards..................................................................................15
2.2 Circuit Board/Schematic Diagrams and Parts List.......................................................................... 17
Chapter 3 UHF Troubleshooting Charts.......................................................................31
3.1 Troubleshooting Flow Chart for Controller...................................................................................... 31
3.2 Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) ................................................................ 32
3.3 Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) ................................................................ 33
3.4 Troubleshooting Flow Chart for Transmitter ...................................................................................34
3.5 Troubleshooting Flow Chart for Synthesizer...................................................................................35
3.6 Troubleshooting Flow Chart for VCO.............................................................................................. 36
Chapter 4 UHF Band 2 Theory of Operation................................................................37
4.1 Transmitter...................................................................................................................................... 37
4.1.1 General.............................................................................................................................. 37
4.1.2 Power Amplifier.................................................................................................................. 37
4.1.3 Antenna Switch.................................................................................................................. 38
4.1.4 Harmonic Filter .................................................................................................................. 38
4.1.5 Antenna Matching Network................................................................................................ 38
4.1.6 Power Control Integrated Circuit (PCIC)............................................................................ 38
4.2 Receiver.......................................................................................................................................... 39
4.2.1 Receiver Front-End............................................................................................................ 39
4.2.2 Receiver Back-End............................................................................................................ 40
4.3 Frequency Generation Circuitry...................................................................................................... 40
4.4 Synthesizer..................................................................................................................................... 41
4.5 Voltage-Controlled Oscillator (VCO)............................................................................................... 42
Chapter 5 UHF Band 2 CB Layouts, Schematic Diagrams, and Parts List ...............45

4Table of Contents
December 26, 2003 FMR-2045A-2
5.1 Notes For All Schematics and Circuit Boards.................................................................................45
5.2 Circuit Board/Schematic Diagrams and Parts List..........................................................................47
Chapter 6 UHF Band 2 Troubleshooting Charts..........................................................61
6.1 Troubleshooting Flow Chart for Controller......................................................................................61
6.2 Troubleshooting Flow Chart for Receiver (Sheet 1 of 2).................................................................62
6.3 Troubleshooting Flow Chart for Receiver (Sheet 2 of 2).................................................................63
6.4 Troubleshooting Flow Chart for Transmitter ...................................................................................64
6.5 Troubleshooting Flow Chart for Synthesizer...................................................................................65
6.6 Troubleshooting Flow Chart for VCO.............................................................................................. 66
Chapter 7 VHF Theory of Operation..............................................................................67
7.1 Transmitter...................................................................................................................................... 67
7.1.1 General..............................................................................................................................67
7.1.2 Power Amplifier..................................................................................................................67
7.1.3 Antenna Switch..................................................................................................................68
7.1.4 Harmonic Filter...................................................................................................................68
7.1.5 Antenna Matching Network................................................................................................ 68
7.1.6 Power Control Integrated Circuit (PCIC)............................................................................68
7.2 Receiver..........................................................................................................................................69
7.2.1 Receiver Front-End............................................................................................................69
7.2.2 Receiver Back-End ............................................................................................................70
7.2.3 Automatic Gain Control Circuit...........................................................................................70
7.3 Frequency Generation Circuitry......................................................................................................71
7.4 Synthesizer.....................................................................................................................................72
7.5 Voltage-Controlled Oscillator (VCO)...............................................................................................73
Chapter 8 VHF Circuit Board Layouts, Schematic Diagrams and Parts List ............75
8.1 Notes For All Schematics and Circuit Boards.................................................................................75
8.2 Circuit Board/Schematic Diagrams and Parts List..........................................................................77
Chapter 9 VHF Troubleshooting Charts .......................................................................91
9.1 Troubleshooting Flow Chart for Controller......................................................................................91
9.2 Troubleshooting Flow Chart for Receiver (Sheet 1 of 2).................................................................92
9.3 Troubleshooting Flow Chart for Transmitter ...................................................................................94
9.4 Troubleshooting Flow Chart for Synthesizer...................................................................................95
9.5 Troubleshooting Flow Chart for VCO.............................................................................................. 96

Table of Contents 5
FMR-2045A-2 12/26/03
List of Figures
Transmitter Block Diagram .................................................................................................................. 7
UHF Receiver Block Diagram.............................................................................................................. 9
Frequency Generation Unit Block Diagram ....................................................................................... 10
Synthesizer Block Diagram................................................................................................................ 11
VCO Block Diagram........................................................................................................................... 12
UHF (403-470MHz) Main Board Top Side PCB No. 8486458Z02..................................................... 17
UHF (403-470MHz) Main Board Bottom Side PCB No. 8486458Z02 ............................................... 18
UHF Controls And Switches Schematic Diagram.............................................................................. 19
UHF Receiver Front-End Schematic Diagram................................................................................... 20
UHF Receiver Back-End Schematic Diagram ................................................................................... 21
UHF Synthesizer Schematic Diagram ...............................................................................................22
UHF Voltage Controlled Oscillator Schematic Diagram..................................................................... 23
UHF Harmonic Filter Schematic Diagram.......................................................................................... 24
UHF Transmitter Schematic Diagram................................................................................................ 25
Controller ASFIC/ON_OFF Schematic Diagram................................................................................ 30
Transmitter Block Diagram ................................................................................................................ 37
UHF Receiver Block Diagram............................................................................................................ 39
Frequency Generation Unit Block Diagram ....................................................................................... 40
Synthesizer Block Diagram................................................................................................................ 41
VCO Block Diagram........................................................................................................................... 42
UHF Band 2 (450-527 MHz) Main Board Top Side PCB No. 8486686Z01 ....................................... 47
UHF Band 2 (450-527 MHz) Main Board Bottom Side PCB No. 8486686Z01.................................. 48
UHF Band 2 Controls and Switches Schematic Diagram.................................................................. 49
UHF Band 2 Receiver Front End Schematic Diagram....................................................................... 50
UHF Band 2 Receiver Back End Schematic Diagram ....................................................................... 51
UHF Band 2 Synthesizer Schematic Diagram................................................................................... 52
UHF Band 2 Voltage Controlled Oscillator Schematic Diagram ........................................................ 53
UHF Band 2 Harmonic Filter Schematic Diagram ............................................................................. 54
UHF Band 2 Transmitter Schematic Diagram.................................................................................... 55
Controller ASFIC/ON_OFF Schematic Diagram................................................................................ 60
Transmitter Block Diagram ................................................................................................................ 67
VHF Receiver Block Diagram ............................................................................................................ 69
Frequency Generation Unit Block Diagram ....................................................................................... 71
Synthesizer Block Diagram................................................................................................................ 72
VCO Block Diagram........................................................................................................................... 73
VHF (136-174MHz) Main Board Top Side PCB No. 8486473Z03..................................................... 77
VHF (136-174MHz) Main Board Bottom Side PCB No. 8486473Z03................................................ 78
VHF Controls And Switches Schematic Diagram .............................................................................. 79
VHF Receiver Front-End Schematic Diagram ................................................................................... 80
VHF Receiver Back-End Schematic Diagram.................................................................................... 81
VHF Synthesizer Schematic Diagram................................................................................................ 82
VHF Voltage Controlled Oscillator Schematic Diagram..................................................................... 83
VHF Transmitter Schematic Diagram ................................................................................................ 84
Controller ASFIC/ON_OFF Schematic Diagram................................................................................ 90

6Table of Contents
12/26/03 FMR-2045A-2
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FMR-2045A-2 December 26, 2003
UHF Theory of Operation: Transmitter 7
Chapter 1 UHF Theory of Operation
1.1 Transmitter
Figure 1-1. Transmitter Block Diagram
1.1.1 General
(Refer to Figure 1-1.)
The UHF transmitter contains five basic circuits:
• Power amplifier
• Antenna switch
• Harmonic filter
• Antenna matching network
• Power control integrated circuit (PCIC)
1.1.2 Power Amplifier
The power amplifier consists of two devices:
• 9Z67 LDMOS driver IC (U101)
• PRF1507 LDMOS PA (Q110)
The 9Z67 LDMOS driver IC contains a two-stage amplification with a supply voltage of 7.3V.
This RF power amplifier is capable of supplying an output power of 0.3W (pin 6 and 7) with an input
signal of 2mW (3dBm) (pin16). The current drain would typically be 160mA while operating in the
frequency range of 403-470 MHz.
The PRF1507 LDMOS PA is capable of supplying an output power of 7W with an input signal of
0.3W. The current drain would typically be 1300mA while operating in the frequency range of
403-470 MHz. The power output can be varied by changing the biasing voltage.
PA - Final
Antenna
PA
Driver
Vcontrol Vcontrol
From VCO
Jack
Antenna Switch/
Harmonic Filter/
Matching Network
PCIC
Stage

December 26, 2003 FMR-2045A-2
8UHF Theory of Operation: Transmitter
1.1.3 Antenna Switch
The antenna switch circuit consists of two PIN diodes (CR101 and CR102), a pi network (C107,
L104 and C106), and two current limiting resistors (R101, R170). In the transmit mode, B+ at PCIC
(U102) pin 23 will go low and turn on Q111 where a B+ bias is applied to the antenna switch circuit to
bias the diodes “on.” The shunt diode (CR102) shorts out the receiver port, and the pi network, which
operates as a quarter wave transmission line, transforms the low impedance of the shunt diode to a
high impedance at the input of the harmonic filter. In the receive mode, the diodes are both off, and
hence, there exists a low attenuation path between the antenna and receiver ports.
1.1.4 Harmonic Filter
The harmonic filter consists of C104, L102, C103, L101 and C102. The design of the harmonic filter
for UHF is that of a modified Zolotarev design. It has been optimized for efficiency of the power
module. This type of filter has the advantage that it can give a greater attenuation in the stop-band
for a given ripple level. The harmonic filter insertion loss is typically less than 1.2 dB.
1.1.5 Antenna Matching Network
A matching network which is made up of L116 is used to match the antenna's impedance to the
harmonic filter. This will optimize the performance of the transmitter and receiver into an antenna.
1.1.6 Power Control Integrated Circuit (PCIC)
The transmitter uses the Power Control IC (PCIC), U102 to regulate the power output of the radio.
The current to the final stage of the power module is supplied through R101, which provides a
voltage proportional to the current drain. This voltage is then fed back to the Automatic Level Control
(ALC) within the PCIC to regulate the output power of the transmitter.
The PCIC has internal digital to analog converters (DACs) which provide the reference voltage of the
control loop. The reference voltage level is programmable through the SPI line of the PCIC.
There are resistors and integrators within the PCIC, and external capacitors (C133, C134 and C135)
in controlling the transmitter rising and falling time. These are necessary in reducing the power
splatter into adjacent channels.
CR105 and its associated components are part of the temperature cut-back circuitry. It senses the
printed circuit board temperature around the transmitter circuits and output a DC voltage to the
PCIC. If the DC voltage produced exceeds the set threshold in the PCIC, the transmitter output
power will be reduced so as to reduce the transmitter temperature.

FMR-2045A-2 December 26, 2003
UHF Theory of Operation: Receiver 9
1.2 Receiver
Figure 1-2. UHF Receiver Block Diagram
1.2.1 Receiver Front-End
(Refer to the UHF Receiver Front-End Schematic Diagram on page 20 and the UHF Transmitter
Schematic Diagram on page 25.)
The RF signal is received by the antenna and applied to a low-pass filter. For UHF, the filter consists
of L101, L102, C102, C103, C104. The filtered RF signal is passed through the antenna switch. The
antenna switch circuit consists of two PIN diodes (CR101 and CR102) and a pi network (C106, L104
and C107).The signal is then applied to a varactor tuned bandpass filter. The UHF bandpass filter
comprises of L301, L302, C302, C303, C304, CR301 and CR302. The bandpass filter is tuned by
applying a control voltage to the varactor diodes (CR301 and CR302) in the filter.
The bandpass filter is electronically tuned by the DACRx from IC404 which is controlled by the
microprocessor. Depending on the carrier frequency, the DACRx will supply the tuned voltage to the
varactor diodes in the filter. Wideband operation of the filter is achieved by shifting the bandpass filter
across the band.
The output of the bandpass filter is coupled to the RF amplifier transistor Q301 via C307. After being
amplified by the RF amplifier, the RF signal is further filtered by a second varactor tuned bandpass
filter, consisting of L306, L307, C313, C317, CR304 and CR305.
Both the pre and post-RF amplifier varactor tuned filters have similar responses. The 3 dB bandwidth
of the filter is about 50 MHz. This enables the filters to be electronically controlled by using a single
control voltage which is DACRx.
Crystal
Filter
Mixer
Varactor
Tuned Filter
RF Amp
Varactor
Tuned Filter
Pin Diode
Antenna
Switch
RF Jack
Antenna
Control Voltage
from ASFIC
First LO
from VCO
Second LO
IF Amp
455kHz
Filter
Switch
455kHz
Filter
455kHz
Filter
Switch
Demodulator
RSSI
Limiter
Recovered Audio
BW SEL
U301

December 26, 2003 FMR-2045A-2
10 UHF Theory of Operation: Frequency Generation Circuitry
The output of the post-RF amplifier filter which is connected to the passive double balanced mixer
consists of T301, T302 and CR306. Matching of the filter to the mixer is provided by C381. After
mixing with the first LO signal from the voltage controlled oscillator (VCO) using low side injection,
the RF signal is down-converted to the 44.85 MHz IF signal.
The IF signal coming out of the mixer is transferred to the crystal filter (FL301) through a resistor pad
and a diplexer (C322 and L310). Matching to the input of the crystal filter is provided by C324 and
L311. The crystal filter provides the necessary selectivity and intermodulation protection.
1.2.2 Receiver Back-End
(Refer to UHF Receiver Back-End Schematic Diagram on page 21.)
The output of crystal filter FL301 is matched to the input of first IF amplifier transistor Q302 by L330.
Voltage supply to the IF amplifier is taken from the receive 5 volts (R5). The IF amplifier provides a
gain of about 16dB. The amplified first IF signal is then coupled into U301 (pin 1) via C360 and L332
which provides the matching for the first IF amplifier and U301.
Within U301, the first IF 44.85 MHz signal mixes with the 44.395 MHz second local oscillator (2nd
LO) to produce the second IF signal at 455 kHz. The second LO signal frequency is determined by
crystal Y300. The second IF signal (455 kHz) is then filtered by an external ceramic filter FL302
before being amplified by the second IF amplifier within U301. Again, the signal is filtered by a
second external ceramic filter FL303 or FL304 depending on the selected channel spacing. FL303 is
used for 20/25 kHz channel spacing whereas FL304, for 12.5 kHz channel spacing. The simple
circuit consisting of U302, CR312, CR313 and resistors R345, R360, R321 and R324 divert the
second IF signal according to the BW_SEL line. The filtered output of the second IF signal is applied
to the limiter input pin of U301.
The IF IC (U301) contains a quadrature detector using a ceramic phase-shift element (Y301) to
provide audio detection. Internal amplification provides an audio output level around 120mVrms
(@60% deviation) from pin 8 of U301. This demodulated audio is fed to the ASFIC_CMP IC (U404)
in the controller section.
The IF IC (U301) also performs several other functions. It provides a received signal-strength
indicator (RSSI) with a dynamic range of 70 dB. The RSSI is a dc voltage monitored by the
microprocessor, and used as a peak indicator during the bench tuning of the receiver front-end
varactor filter.
1.3 Frequency Generation Circuitry
Figure 1-3. Frequency Generation Unit Block Diagram
Voltage
Multiplier
Synthesizer
U201
Dual
Tran-
sistor
Loop
Filter
VCOBIC
U241
Low
Pass
Filter
Second
Buffer
Attenuator
To
Mixer
To
PA Driver
VCP
Vmult1 Aux3
Aux4
MOD Out
Modulating
Signal
Vmult2
Rx VCO Circuit
Tx VCO Circuit
TRB
16.8 MHz
Ref. Osc.
Rx Out
Tx Out

FMR-2045A-2 December 26, 2003
UHF Theory of Operation: Synthesizer 11
The Frequency Generation Circuitry is composed of two main ICs:
• Fractional-N synthesizer (U201)
• VCO/Buffer IC (U241)
Designed in conjunction to maximize compatibility, the two ICs provide many of the functions that
normally would require additional circuitry. The synthesizer block diagram illustrates the interconnect
and support circuitry used in the region. Refer to the relevant schematics for the reference
designators.
The synthesizer is powered by regulated 5V and 3.3V which come from U247 and U248 respectively.
The synthesizer in turn generates a super-filtered 4.5V which powers U241.
In addition to the VCO, the synthesizer must interface with the logic and ASFIC circuitry.
Programming for the synthesizer is accomplished through the data, clock and chip select lines from
the microprocessor. A 3.3V dc signal from the synthesizer lock detect line indicates to the
microprocessor that the synthesizer is locked.
Transmit modulation from the ASFIC is supplied to pin 10 of U201. Internally the audio is digitized by
the Fractional-N and applied to the loop divider to provide the low-port modulation. The audio runs
through an internal attenuator for modulation balancing purposes before going out to the VCO.
1.4 Synthesizer
(Refer to UHF Synthesizer Schematic Diagram on page 22.)
Figure 1-4. Synthesizer Block Diagram
The Fractional-N Synthesizer uses a 16.8MHz crystal (FL201) to provide a reference for the system.
The LVFractN IC (U201) further divides this to 2.1MHz, 2.225 MHz, and 2.4 MHz as reference
frequencies. Together with C206, C207, C208, R204 and CR203, they build up the reference
oscillator which is capable of 2.5ppm stability over temperatures of -30 to 85°C. It also provides
16.8 MHz at pin 19 of U201 to be used by the ASFIC.
DATA
CLK
CEX
MODIN
VCC, DC5V
XTAL1
XTAL2
WARP
PREIN
VCP
REFERENCE
OSCILLATOR
VOLTAGE
MULTIPLIER
VOLTAGE
CONTROLLED
OSCILLATOR
2-POLE
LOOP
FILTER
DATA (U409 PIN 100)
CLOCK (U409 PIN 1)
CSX (U409 PIN 2)
M
OD IN (U404 PIN 40)
+5V (U247 PIN 4)
7
8
9
10
13, 30
23
24
25
32
47
VMULT2 VMULT1
BIAS1
SFOUT
AUX3
AUX4
IADAPT
IOUT
GND
FREFOUT
LOCK 4
19
6, 22, 23, 24
43
45
3
2
28
14 15
40
FILTERED 5V
STEERING
LINE
LOCK (U409 PIN 56)
PRESCALER IN
LO RF INJECTION
TX RF INJECTION
(1ST STAGE OF P
A
FREF (U201 PIN 21 & U404 PIN 34)
39
BIAS2
41
DUAL
TRANSIS
DUAL
TRANSIS-
48
5V R5
5, 20, 34, 36
(U248 PIN 5)
AUX1
VDD, 3.3V MODOUT
U251
LOW VOLTAGE
FRACTIONAL-N
SYNTHESIZER
TORS
TORS

December 26, 2003 FMR-2045A-2
12 UHF Theory of Operation: Voltage-Controlled Oscillator (VCO)
The loop filter which consist of C231, C232, C233, R231, R232 and R233 provides the necessary dc
steering voltage for the VCO and determines the amount of noise and spur passing through.
In achieving fast locking for the synthesizer, an internal adapt charge pump provides higher current
at pin 45 of U201 to put synthesizer within the lock range. The required frequency is then locked by
normal mode charge pump at pin 43.
Both the normal and adapt charge pumps get their supply from the capacitive voltage multiplier
which is made up of C258, C259, C228, triple diode CR201 and level shifters U210 and U211. Two
3.3V square waves (180 degrees out of phase) are first shifted to 5V, then along with regulated 5V,
put through arrays of diodes and capacitors to build up 13.3V at pin 47 of U201.
1.5 Voltage-Controlled Oscillator (VCO)
(Refer to the UHF Voltage-Controlled Oscillator Schematic Diagram on page 23.)
Figure 1-5. VCO Block Diagram
Presc
RX
TX
Second
Buffer Low Pass
Filter
Attenuator
Pin8
Pin14
Pin10
Level Shifter
Network
5V
(U201 Pin28)
VCC Buffers
TX RF Injection
U201 Pin 32
AUX4 (U201 Pin3)
AUX3 (U201 Pin2)
Prescaler Out
Pin 12Pin 19
Pin 20
TX/RX/BS
Switching Network
U241
VCOBIC
Rx
Active Bias
Tx
Active Bias
Pin2
Rx-I adjust
Pin1
Tx-I adjust
Pins 9,11,17
Pin18
Vsens
Circuit
Pin15
Pin16
RX VCO
Circuit
TX VCO
Circuit
RX Tank
TX Tank
Pin7
Vcc-Superfilter
Collector/RF in
Pin4
Pin5
Pin6
RX
TX
(U201 Pin28)
Rx-SW
Tx-SW
Vcc-Logic
(U201 Pin28)
Steer Line
Voltage
(VCTRL)
Pin13
Pin3
TRB_IN
LO RF INJECTION
VSF
VSF
VSF

FMR-2045A-2 December 26, 2003
UHF Theory of Operation: Voltage-Controlled Oscillator (VCO) 13
The VCOBIC (U241) in conjunction with the Fractional-N synthesizer (U201) generates RF in both
the receive and the transmit modes of operation. The TRB line (U241 pin 19) determines which
oscillator and buffer will be enabled. A sample of the RF signal from the enabled oscillator is routed
from U241 pin 12, through a low pass filter, to the prescaler input (U201 pin 32). After frequency
comparison in the synthesizer, a resultant CONTROL VOLTAGE is received at the VCO. This
voltage is a dc voltage between 3.5V and 9.5V when the PLL is locked on frequency.
The VCOBIC (U241) is operated at 4.54V (VSF) and Fractional-N synthesizer (U201) at 3.3V. This
difference in operating voltage requires a level shifter consisting of Q260 and Q261 on the TRB line.
The operation logic is shown in Table 1-1.
In receive mode, U241 pin 19 is low or grounded. This activates the receive VCO by enabling the
receive oscillator and the receive buffer of U241. The RF signal at U241 pin 8 is run through a
second buffer to improve mixer to receive VCO isolation. The resulting RF signal is LO RF
INJECTION and it is applied to the mixer at T302. (Refer to the UHF Receiver Front-End Schematic
Diagram on page 20.)
During the transmit condition, when PTT is depressed, a five-volt current is applied to U241 pin 19.
This activates the transmit VCO by enabling the transmit oscillator and the transmit buffer of U241.
The RF signal at U241 pin 10 is injected into the input of the PA module (U101 pin16). This RF signal
is the TX RF INJECTION. Also in transmit mode, the audio signal to be frequency modulated onto
the carrier is received through the U201 pin 41.
When a high impedance is applied to U241 pin 19, the VCO is operating in BATTERY SAVER mode.
In this case, both the receive and transmit oscillators as well as the receive transmit and prescaler
buffer are turned off.
Table 1-1. Level Shifter Logic
Desired Mode AUX 4 AUX 3 TRB
Tx Low High (@3.2V) High (@4.8V)
Rx High Low Low
Battery Saver Low Low Hi-Z/Float (@2.5V)

December 26, 2003 FMR-2045A-2
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14 UHF Theory of Operation: Voltage-Controlled Oscillator (VCO)

Chapter 2 UHF Circuit Board Layouts, Schematic
Diagrams and Parts List
2.1 Notes for All Schematics and Circuit Boards
* Component is frequency sensitive. Refer to the Electrical Parts List for value and usage.
1. Unless otherwise stated, resistances are in Ohms (k = 1000), and capacitances are in picofarads
(pF) or microfarads (µF).
2. DC voltages are measured from point indicated to chassis ground using a Motorola DC
multimeter or equivalent. Transmitter measurements should be made with a 1.2 µH choke in
series with the voltage probe to prevent circuit loading.
3. Reference Designators are assigned in the following manner:
100 Series = Transmitter
200 Series = Frequency Generation
300 Series = Receiver
400/500 Series = Controller
600 Series = Keypad board
4. Interconnect Tie Point Legend:
UNSWB+ = Unswitch Battery Voltage (7.5V)
SWB+ = Switch Battery Voltage (7.5V)
R5 = Receiver 5 Volts
CLK = Clock
Vdda = Regulated 3.3 Volts (for analog)
Vddd = Regulated 3.3 Volts (for digital)
CSX = Chip Select Line
SYN = Synthesizer
DACRX = Digital-to-Analog Voltage (for Receiver Front-End Filter)
VSF = Voltage Super Filtered (5 volts)
VR = Voltage Regulator
SIX-LAYER CIRCUIT BOARD DETAIL VIEWING
COPPER STEPS IN PROPER LAYER SEQUENCE
LAYER 1 (L1)
LAYER 2 (L2)
LAYER 3 (L3)
LAYER 4 (L4)
LAYER 5 (L5)
LAYER 6 (L6)
INNER LAYERS
SIDE 1
SIDE 2

December 26, 2003 FMR-2045A-2
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16 UHF Circuit Board Layouts, Schematic Diagrams and Parts List: Notes for All Schematics and Circuit Boards

Circuit Board/Schematic Diagrams and Parts List 17
FMR-2045A-2 December 26, 2003
2.2 Circuit Board/Schematic Diagrams and Parts List
Figure 2-1. UHF (403-470MHz) Main Board Top Side PCB No. 8486458Z02
C505
R507
C502
VR501
12
3
5PB501
4
32
FL304
C521
FL302
VR440
C349
R365
2
Y301
4
32
FL303
C352
R321
R324
R345
R355
R360
C362
R342
4
58
U302
C324
C325
C338
2
34
5
6
FL301
L311
L330
SH323
C320
C322
C381
L309
L310
R308
R309
R310
SH303
6
43
T301
6
4
3
T302
C319 C375
R348
TP202
TP302
12
3
5PB504
C511
C512C513
C514
C520
43
2
CR503
1
2
3
5
PB505
Q502
Q505
R501
R502
R505
R506
VR443
C140
C141
L116
C101
C102
C103
C104
C106
C107
C175
CR101
CR102
L101 L102
L104
L105
SH100
C301
C302
C303
C304
C305
C308
CR301
CR302
L301
L302
R301
R302
SH301
1
2
3
Q110
C109
C111
C112
L106
C110
C113
C114
L107 L115
L114
C115
C116
C117
C118
C120
C121
C127
L108
L109
R103
R106
R107
R108
R175
R176
C119
C171
R104
R120
R171
R173
R174
C122
C125
C129
C160
C161
C165
C169
L113
R161
1
16
8
9
U101
C131
C166
SH101
L160
12
3
5
PB502
12
3
5PB503
B503
B504
6
4
31
FL201
C432
TP201
C203
C210
C211
C212
C213
C214
C217
C220
C228
C229
C230
C233
C235
C238 C257
C260
C291
C292
C294
C297
CR201
L201
L202
L203
L232
4
3Q210
4
3
Q260
R255
R256
SH201
U247
C247
C248 C251
C253
C271
C272
C273
C276
C285
C286
C289
C370
C374
C386
1
3
L243
1
3
L253
L271
L273
L282
L321
Q241
4
3
Q261
R243
R248
R253
R260
R333
R339
SH241
32
17
16
1
U406
1
40
J400
22
21 8
7
1
U405
C423
E407
E408
E409
R410
R418
R437
C427C428
1
45
8
U407
R429
R492
SH400
C424
C429
R408
R428
R478
C425 C426
C402 C467
C480
C482
CR440
Q403
4
3
Q405
R416
R447 R448
R451
R452
R453
R454
R455 R456
R481
C401 CR412
Q400
R401
R402
R405
SH401
TP415
R407
R427
R476
4
5
8
U400
C403
C400
C406
R403
R406
4
3
Q417
CR413
TP406
22
20
1
21
J403
L400
R421
TP405
VR434
VR450
C441
C471 C472
C473
C490
C491
C492
C493
C494
C495
C496
C497
R477
R450
C404
C443
C444
L401
R435
RT400
TP401
TP402
TP410
VR447
VR449

18 Circuit Board/Schematic Diagrams and Parts List
December 26, 2003 FMR-2045A-2
Figure 2-2. UHF (403-470MHz) Main Board Bottom Side PCB No. 8486458Z02
C449
C463
C524
C525
E401
E402
E403
E404 E405
E406
26
176
51
U409
C453
C456
R411
R432
L410
L411
C458
C459
C466
C526
C527
C528
C529
E400
R409
R457
C431
C433
C436 C437
3
FL401
R414
R415
R420
R426
R463
C434
C435
CR411
Q416
R419
R460
R461
R462
SH402
U410
C328
C337
C359
C523
R374
R375
1
45
8
U303
VR442
C277 C278
C279
C522
L505
U248
VR441 VR506
C358
C383
C390
R373
R376
R377
R378
R370
R371
R372
C202
C204
C208
C223
C263
C264
C293
C298
CR203 L261
R204
SH202
C201
C219
C231
C232
C234
R201
R202
R231 R232
R233
1
37
25
13
U201
C206
C207
C218
C224
C258
C259
C265
C296
R281
5
43
U210
54
3
U211
C442
C445
R473
VR432
VR433
VR445
VR446
VR448 11
1
20
10
U420
C475
R431 R498
1
37
25
13
U404
C414
C415
C430
C450 C451
C452
C476
4
3
Q410
R471
SH403
VR460
C405
C408
C409
C410
C411
C440
R434
R436
C407
C416
C419
C420 C421
C422
C447 C448
C479
C481
R400
R413
R423 R424
R425
R445
R449
R472
R475
R499
C252 C254
C255
CR251
L251
R251
R252
R254
SH242
11
1
20
10
U241
C241
C242
C243
C244
C245
C246 C250
C281
C295
C371 C372
C373
C378
CR241
CR242
CR243
L241
L242
L281
Q310
R110
R111
R112
R241
R242
R244
R245
R330 R331
R332
R349
C105
C123
C126
C128
C130
C133
C134 C135
C138
C150
C151
C152
C170
C174
E101
L112
R102
R109
R130
R131
R132
R136
1
17
9
25
U102
R329
VR439
C172
C173
CR105
R172
C132
H101
R133
P100
C108
CR103
CR160
4
3
Q111
R101
R170
2
3
4
1
J101
J102
C503
CR306
CR501
F501 SH304
1
2
3
B501
VR444
C306
C307
C309
C310
C311
C312
C313
C314
C315
C316
C317
C318
C321
C380
CR303
CR304
CR305
L303
L304
L305
L306
L307
Q301
R303
R304
R305
R306
R307
R328
R340
SH302
4
32
Y300
C355
L331 L332 R359
C334
C350
R366
R367
R368
R369
SH322
11
1
20
10
U301
C327
C344
C348
C360
C366
Q302
R311
R312 R344
C326
C361
C382
CR311
R313
R314
R315
C329
C343
C345
C346
C347
C351
C357
CR312 CR313
Q320
R350
R358
R361
R363
R364
C364 C367
C385
L325
R320 R322
R346
4
53
2S502
4
C
8
C
2
1
S501

Circuit Board/Schematic Diagrams and Parts List 19
FMR-2045A-2 December 26, 2003
Figure 2-3. UHF Controls And Switches Schematic Diagram
B504
if
B503
LI_ION
VR501
6.8V
0.47uF
C502
C505
100pF
SWITCH
S502
4
1
LOW
5
HIGH
36
TAB1 7
TAB2
2
R507
0
MECH_SWB+
Vdda
VOL
P100
M100
M101
VR441
6.8V
6.8V
VR442
PB503
SWITCH 12
.01uF
C522
VR444
6.8V
1
2SWITCH
PB501
2
PB502
SWITCH 1
6.8V
VR440
.01uF
C521
2SWITCH
PB504
1
.01uF
C523
EMER
PTT
SB2
SB3
SB1
PB505
12 SWITCH
C520
.01uF 6.8V
VR443
Vdda
4
3
2R506
47K
5
1
6
IMX1
Q505
10K
R505
R502
180
680
R501
GREEN_LED
SWB+
RED_LED
Q502
3
1
24
CR503
CR501
1
210V
VR439 100pF
C503
24V
F501
21
L505
390nH
VR506
6.8V
BATT_CODE
RADIO_CODE
UNSWB+
BATT-
BATT+ DATA
1NEG
3POS
CONN_J
B501
2
BATTERY_CONTACT
TAB1
1TAB2
2TAB3 3
TAB4 4
TAB5 5
RF_JACK
ANTENNA_NUT
J102
C140
9.75nH
L116
1
2
3
J101
RF_JACK
4GND
K2
K3
A1
A2
A3
K1
CR160
C141
NU
NU
RTA0
RTA1
RTA2
RTA3
C514
100pF
100pF
C512
C511 C513
100pF 100pF
SWITCH
S501
C1
GND GND1
PC0
1PC1
2PC2 PC3
C0
C0
C1 DUMMY
79
48
ZMY0130015-C

20 Circuit Board/Schematic Diagrams and Parts List
December 26, 2003 FMR-2045A-2
Figure 2-4. UHF Receiver Front-End Schematic Diagram
CR303
2
3
1
100K
R302
7.5K
R340
CR302
2.0K
R303
100pF
C308
100pF
C307
C305
13.9nH
L302
20pF
9.1pF
C304 22nH
L303
C309
100pF
1
Q301
R328
0
3
2
G
3.9pF
C303
3.6pF
C301
100K
R301
C302
10pF
CR301
L301
13.9nH
RX_IN
RXFE Bottom Shield
RXFE Top Shield
RX Mixer Diod Shield
SH302
SHIELD
1
1
SHIELD
SH304
SH301
SHIELD
1
Mixer Shield
1
SHIELD
SH303
G
100pF
C321
12K
R304
C314
0.1uF
C315
100pF
180nH
L304
100pF
C310
510
R305
R5
NU
NU
L307
13.9nH C317
9.1pF
R306
100K
C312
6.8pF
CR304
R307
100K
L306
13.9nH
C316 R329
3.9pF 0
7.5pF
C313
C318
10pF
22nH
L305
C306
C311
CR305
C380
.01uF
G
R342
100K
DACRx
G
NU
3
1
2
T301
XFMR
4
6
51
R308
3 1 2
XFMR
T302
R309
0
150nH
L310
R310
C381
CR306
2
34
1
C322
82pF
IF
NU
C375
100pF
16.28nH
L309
4 6
3.6K
R348
C320
16pF
TP302
C319
2.7pF
G
NU
NU NU
10K
R330
NU
240
R331
C370
4.7pF
VCOBUF
C374
100pF
C371
C378
C372
100pF
C373
C386
100pF
4.3K
R339
1
3
2
Q310
L321
180nH R333
12K
R332
0
R349
R5
G
RX_INJ
2580541Z02