58D04_Sec4_Cover 58D04_Section4_VHF 58D04 Section4 VHF

58D04_Section4_VHF 58D04_Section4_VHF

User Manual: 58D04_Section4_VHF

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Professional Radio
GP Series
VHF (136-174MHz)
Service Information
Issue: November 2004
ii
Computer Software Copyrights
The Motorola products described in this manual may include copyrighted Motorola computer programs stored
in semiconductor memories or other media. Laws in the United States and other countries preserve for
Motorola certain exclusive rights for copyrighted computer programs, including the exclusive right to copy or
reproduce in any form, the copyrighted computer program. Accordingly, any copyrighted Motorola computer
programs contained in the Motorola products described in this manual may not be copied or reproduced in
any manner without the express written permission of Motorola. Furthermore, the purchase of Motorola
products shall not be deemed to grant, either directly or by implication, estoppel or otherwise, any license
under the copyrights, patents or patent applications of Motorola, except for the normal non-exclusive royalty-
free license to use that arises by operation of law in the sale of a product.
iii
Table of Contents
Chapter 1 MODEL CHART AND TECHNICAL SPECIFICATIONS
1.0 GP320/GP340/GP360/GP380 Model Chart.........................................................1-1
2.0 GP140 Model Chart .............................................................................................1-2
3.0 GP640/GP680 Model Chart .................................................................................1-2
4.0 GP1280 Model Chart ...........................................................................................1-3
5.0 GP240/GP280/GP540/GP580 Model Chart.........................................................1-4
6.0 Technical Specifications ......................................................................................1-5
Chapter 2 THEORY OF OPERATION
1.0 Introduction ..........................................................................................................2-1
2.0 VHF Transmitter...................................................................................................2-1
2.1 Power Amplifier ..............................................................................................2-1
2.2 Antenna Switch...............................................................................................2-2
2.3 Harmonic Filter ...............................................................................................2-2
2.4 Antenna Matching Network ............................................................................2-2
2.5 Power Control Integrated Circuit (PCIC) ........................................................2-2
3.0 VHF Receiver (for all models except those with PCB8486473Z04) ....................2-3
3.1 Receiver Front-End ........................................................................................2-3
3.2 Receiver Back-End.........................................................................................2-4
3.3 Automatic Gain Control (AGC) .......................................................................2-5
4.0 VHF Receiver (for models with PCB 8486473Z04) .............................................2-6
4.1 Receiver Front-End ........................................................................................2-6
4.2 Receiver Back-End.........................................................................................2-7
4.3 Automatic Gain Control (AGC) .......................................................................2-8
5.0 Frequency Generation Circuit ..............................................................................2-8
5.1 Synthesizer.....................................................................................................2-9
5.2 Voltage Controlled Oscillator (VCO).............................................................2-10
6.0 Voice Storage (GP1280)....................................................................................2-12
Chapter 3 TROUBLESHOOTING CHARTS
1.0 Troubleshooting Flow Chart for Receiver for all models except those with PCB
8486473Z04.........................................................................................................3-1
2.0 Troubleshooting Flow Chart for Receiver for models with PCB 8486473Z04......3-3
3.0 Troubleshooting Flow Chart for Transmitter ........................................................3-5
4.0 Troubleshooting Flow Chart for Synthesizer........................................................3-6
5.0 Troubleshooting Flow Chart for VCO...................................................................3-7
6.0 Troubleshooting Flow Chart for Receive Message/Personal Memo Recording...3-8
7.0 Troubleshooting Flow Chart for Message Playback.............................................3-9
iv
Chapter 4 VHF PCB/SCHEMATICS/PARTS LISTS
1.0 Allocation of Schematics and Circuit Boards .......................................................4-1
1.1 Controller Circuits...........................................................................................4-1
1.2 Voice Storage Facility..................................................................................... 4-1
2.0 VHF PCB 8486062B12 / Schematics ..................................................................4-5
3.0 VHF PCB 8486062B12 Parts List...................................................................... 4-13
4.0 VHF PCB 8486101B09 / Schematics (GP1280)................................................ 4-17
5.0 VHF PCB 8086101B09 Parts List (GP1280) ..................................................... 4-21
6.0 VHF PCB 8486062B14...................................................................................... 4-25
7.0 VHF PCB 8486062B14 Parts List...................................................................... 4-27
8.0 VHF PCB 8486101B10...................................................................................... 4-31
9.0 VHF PCB 8486101B10 Parts List (GP1280) ..................................................... 4-33
10.0 VHF PCB 8486062B16......................................................................................4-37
11.0 VHF PCB 8486062B16 Parts List......................................................................4-45
12.0 VHF PCB 8486062B17......................................................................................4-49
13.0 VHF PCB 8486062B17 Parts List......................................................................4-51
14.0 VHF PCB 8486101B11 .....................................................................................4-55
15.0 VHF PCB 8486101B11 Parts List......................................................................4-57
16.0 VHF PCB 8486473Z04 ..................................................................................... 4-61
17.0 VHF PCB 8486473Z04 Parts List ......................................................................4-69
Chapter 1
MODEL CHART AND TECHNICAL SPECIFICATIONS
1.0 GP320/GP340/GP360/GP380 Model Chart
x = Indicates one of each is required.
* = Service replacement boards
Professional GP300 Series (VHF)
Model Description
MDH25KDC9AN0_E GP320 VHF 136-174MHz 5W 1-Ch
MDH25KDC9AN3_E GP340 VHF 136-174MHz 5W 16-Ch
MDH25KDF9AN5_E GP360 VHF 136-174MHz 5W 255-Ch
MDH25KDH9AN6_E GP380 VHF 136-174MHz 5W 255-Ch
Item Description
X PMLD4121_ *GP320 VHF Back Cover Kit
XPMLD4117_ *GP340 VHF Back Cover Kit
X PMLD4119_ *GP360 VHF Back Cover Kit
XPMLD4118_ *GP380 VHF Back Cover Kit
X 6864110B12 GP320 Basic User Guide
X6864110B13 GP340 Basic User Guide
X 6864110B16 GP360 Basic User Guide
X6864110B18 GP380 Basic User Guide
XXXX PMAD4023_ VHF 14cm (150-161 MHz) Antenna
XXXX HNN9008_ Battery, NiMH Standard
1-2 MODEL CHART AND TECHNICAL SPECIFICATIONS
2.0 GP140 Model Chart
3.0 GP640/GP680 Model Chart
Professional GP140 (VHF)
Model Description
MDH25KDC9AA3_E GP140 VHF 136-174 MHz 5W 16 Ch
Item Description
XPMLE4109_ *GP140 UHF Back Cover Kit
X 6864110B25 GP140 Basic User Guide
XPMAD4023_ VHF 14cm (150-161 MHz) Antenna
X HNN9008_ Battery, NiMH Standard
x = Indicates one of each is required.
* = Service replacement boards
Professional GP600 Series (VHF)
Model Description
MDH25KDC9ACK3_E GP640 VHF 136-174 MHz 5W
MDH25KDH9CK6_E GP680 VHF 136-174 MHz 5W
Item Description
XPMLD4113_ *GP640 VHF Back Cover Kit
X PMLD4114_ *GP680 VHF Back Cover Kit
X6864110B14 GP640 Basic User Guide
X 6864110B19 GP680 Basic User Guide
X X PMAD4023_ VHF 14cm (150-161 MHz) Antenna
X X HNN9008_ Battery, NiMH Standard
x = Indicates one of each is required.
* = Service replacement boards
GP1280 Model Chart 1-3
4.0 GP1280 Model Chart
Professional GP1280 (VHF)
Model Description
MDH25KDN9CK8_E GP1280 VHF 136-174 MHz 5W
Item Description
XPMLD4120_ *GP1280 VHF Back Cover Kit
X 6864110B20 GP1280 Basic User Guide
XPMAD4023_ VHF 14cm (150-161 MHz) Antenna
X HNN9008_ Battery, NiMH Standard
x = Indicates one of each is required.
* = Service replacement boards.
1-4 MODEL CHART AND TECHNICAL SPECIFICATIONS
5.0 GP240/GP540/GP280/GP580 Model Chart
One user guide is selectable via option.
x = Indicates one of each is required.
* = Service replacement boards.
Professional GP200/GP500 Series (VHF)
Model Description
MDH25KDC9GC3 GP540 VHF 136-174MHz 5W
MDH25KDH9GC6 GP580 VHF 136-174MHz 5W
MDH25KDC9GB3 GP240 VHF 136-174MHz 5W
MDH25KDH9GB6 GP280 VHF 136-174MHz 5W
Item Description
X X *PMLD4170_ GP240/GP540 VHF Back Cover Kit
X X *PMLD4171_ GP280/GP580 VHF Back Cover Kit
X X *PMLD4216_ GP240/GP540 VHF Front Housing Kit
X X *PMLD4373_ GP280/GP580 VHF Front Housing Kit
X X 6864120B15 GP240/GP280 User Guide (English)
X X 6864120B16 GP240/GP280 User Guide (ENG, RUS, FR, TUR)
X X 6864120B17 GP240/GP280 User Guide (GER, SPA, POR, IT)
X X 6864120B18 GP240/GP280 User Guide (SWE,NL, DAN, FIN)
X X 6864120B19 GP240/GP280 User Guide (CZ, PL, HU, RO)
X X 6864120B20 GP540/GP580 User Guide (English)
X X 6864120B21 GP540/GP580 User Guide (ENG, RUS, FR, TUR)
X X 6864120B22 GP540/GP580 User Guide (GER, SPA, POR, IT)
X X 6864120B23 GP540/GP580 User Guide (SWE,NL, DAN, FIN)
X X 6864120B24 GP540/GP580 User Guide (CZ, PL, HU, RO)
XXXX NAD6502_ Antenna (146-174 MHz) HELIFLEX
XXXX HNN9008_ Battery, NiMH Standard
Technical Specifications 1-5
6.0 Technical Specifications
Data is specified for +25°C unless otherwise stated.
General Specifications
Channel Capacity
GP140
GP240, GP280
GP320
GP340
GP360, GP380
GP540, GP580
GP640, GP680, GP1280
16
128 in conventional Mode
1
16
255
128 in conventional Mode
16 (Conventional)
Power Supply Rechargeable battery 7.5v
Dimensions: H x W x D (mm) Height excluding knobs
With standard high capacity NiMH battery
With ultra high capacity NiMH battery
With NiCD battery
With Lilon battery
GP140/GP240/320/340/360/380/
GP580/640/680
137 x 57.5 x 37.5
137 x 57.5 x 40.0
137 x 57.5 x 40.0
137 x 57.5 x 33.0
With standard high capacity NiMH battery
With ultra high capacity NiMH battery
With NiCD battery
With Lilon battery
GP1280
152 x 57.5 x 37.5
152 x 57.5 x 37.5
152 x 57.5 x 37.5
152 x 57.5 x 37.5
Weight: (gm)
With Standard high capacity NiMH battery
With Ultra high capacity NiMH battery
With NiCD battery
With Lilon battery
GP140/GP240/ GP360/GP280
GP320/GP340/ GP380/GP580
GP540/GP640 GP680
420 428
500 508
450 458
350 358
With Standard high capacity NiMH battery
With Ultra high capacity NiMH battery
With NiCD battery
With Lilon battery
GP1280
460
535
485
390
Average Battery Life @5/5/90 Cycle:
With Standard high capacity NiMH battery
With Ultra high capacity NiMH battery
With NiCD battery
With Lilon battery
Low Power High Power
11 hours 8 hours
14 hours 11 hours
12 hours 9 hours
11 hours 8 hours
Sealing: Withstands rain testing per
MIL STD 810 C/D /E and IP54
Shock and Vibration: Protection provided via impact
resistant housing exceeding MIL STD
810-C/D /E and TIA/EIA 603
Dust and Humidity: Protection provided via environment
resistant housing exceeding MIL STD
810 C/D /E and TIA/EIA 603
1-6 MODEL CHART AND TECHNICAL SPECIFICATIONS
*Availability subject to the laws and regulations of individual countries.
Transmitter VHF
*Frequencies - Full Bandsplit VHF 136-174 MHz
Channel Spacing 12.5/20/25 kHz
Frequency Stability
(-25°C to +55°C, +25° Ref.) ±2.5 ppm
Power 136 - 174 MHz:1-5W
Modulation Limiting
±2.5 @ 12.5 kHz
±4.0 @ 20 kHz
±5.0 @ 25 kHz
FM Hum & Noise -40 dB typical
Conducted/Radiated Emission -36 dBm <1 GHz
-30 dBm >1 GHz
Adjacent Channel Power -60 dB @ 12.5 kHz
-70 dB @ 25 kHz
Audio Response (300 - 3000 Hz) +1 to -3 dB
Audio Distortion <5% typical
Receiver VHF
*Frequencies - Full Bandsplit VHF 136-174 MHz
Channel Spacing 12.5/20/25 kHz
Sensitivity (12 dB SINAD) EIA
Sensitivity (20 dB SINAD) ETS
0.35 µV typical
0.50 µV typical
Intermodulation EIA -65 dB
Adjacent Channel Selectivity -60 dB @ 12.5 kHz
-70 dB @ 25 kHz
Spurious Rejection -70 dB
Rated Audio 0.5W
Audio Distortion @ Rated Audio <3% typical
Hum & Noise -45 dB @ 12.5 kHz
-50 dB @ 20/25 kHz
Audio Response (300 - 3000 Hz) +1 to -3 dB
Conducted Spurious Emission
-57 dBm <1 GHz
-47 dBm >1 GHz
ETS 300 086
Chapter 2
THEORY OF OPERATION
1.0 Introduction
This Chapter provides a detailed theory of operation for the VHF circuits in the radio. For details of
the theory of operation and trouble shooting for the the associated Controller circuits refer to the
Controller Section of this manual.
2.0 VHF Transmitter
(
Refer to Figure 2-1 and the VHF Transmitter schematic diagram
)
The VHF transmitter consists of the following basic circuits:
1. Power amplifier (PA).
2. Antenna switch/harmonic filter.
3. Antenna matching network.
4. Power Control Integrated Circuit (PCIC).
Figure 2-1 VHF Transmitter Block Diagram.
2.1 Power Amplifier
The power amplifier consists of two devices:
1. LDMOS driver IC (U3501)
2. LDMOS PA (Q3501)
The LDMOS driver IC contains two stages of amplification with a supply voltage of 7.3V.
Antenna Switch/
Harmonic Filter
Vcontrol Vcontrol
From
Antenna
Matching
Network
Power
Amplifier
VCO
PA
Driver
PCIC
PA Final
Stage
2-2 THEORY OF OPERATION
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 is typically around 130mA while operating in the
frequency range of 136-174MHz.
The LDMOS PA is capable of supplying an output power of 7W with an input signal of 0.3W. The
current drain is typically around 1800mA while operating in the frequency range of 136-174MHz.
The power output is varied by changing the bias voltage.
2.2 Antenna Switch
The antenna switch circuit consists of two pin diodes, D3521 and D3551, a pi network (C3531,
L3551 and C3550), and three current limiting resistors (R3571, R3572, R3573). In the transmit
mode, B+ at PCIC (U3502) pin 23 goes low to turn on Q3561 where a B+ bias is applied to the
antenna switch circuit to bias the diodes "on". The shunt diode (D3551) 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, creating a low attenuation path between the antenna and receiver
ports.
2.3 Harmonic Filter
The harmonic filter consists of C3532 to C3536, L3531 and L3532. This network forms a low-pass
filter to attenuate harmonic energy of the transmitter to specifications level. The harmonic filter
insertion loss is typically less than 1.2dB.
2.4 Antenna Matching Network
A matching network made up of L3538 and C3537/C3539 is used to match the antenna impedance
to the harmonic filter. This optimizes the performance of the transmitter and receiver into the
antenna.
2.5 Power Control Integrated Circuit (PCIC)
The transmitter uses the PCIC, U3502 to control the power output of the radio by maintaining the
radio current drain. The current to the final stage of the power module is supplied through R3519,
which provides a voltage proportional to the current drain. This voltage is then fedback to the
Automatic Level Control (ALC) within the PCIC to provide loop stability.
The PCIC also contains internal digital to analog converters (DACs) that provide the reference
voltage of the control loop. The voltage level is controlled by the microprocessor through the data
line of the PCIC.
The resistors and integrators within the PCIC, and external capacitors (C3562, C3563 and C3565)
control the transmitter rise and fall times. These are necessary to reduce the power splatter into
adjacent channels.
U3503 and its associated components act as a temperature cut back circuit. This provides the
necessary voltage to the PCIC to cut the transmitter power if the radio temperature gets too high.
VHF Receiver (for all models except those with PCB8486473Z04) 2-3
3.0 VHF Receiver (for all models except those with PCB8486473Z04)
The VHF receiver consists of a front end, back end, and automatic gain control circuits. A block
diagram of the VHF receiver is shown in Figure 2-2. Detailed descriptions of these features are
contained in the paragraphs that follow.
Figure 2-2 VHF Receiver Block Diagram.
3.1 Receiver Front-End
(
Refer to Figure 2-2 and the VHF Receiver Front End schematic diagram
)
The RF signal is received by the antenna and applied to a low-pass filter consisting of L3531,
L3532, C3532 to C3563. The filtered RF signal is passed through the antenna switch. The antenna
switch circuit consists of two pin diodes (D3521 and D3551) and a pi network (C3531, L3551, and
C3550).The RF signal is then applied to a varactor tuned bandpass filter which consists of L3301,
L3303, C3301 to C3304, and D3301. The filter is tuned by applying a control voltage to the varactor
diode (D3301) in the filter.
The bandpass filter is electronically tuned by the DACRx from IC 404 which is controlled by the
microprocessor. Depending on the carrier frequency, the DACRx supplies 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 Q3302 via C3306. After
being amplified by the RF amplifier, the RF signal is further filtered by a second varactor tuned
bandpass filter, consisting of L3305, L3306, C3311 to C3314 and D3302.
Demodulator
Synthesizer
Crystal
Filter
Mixer
Varactor
Tuned Filter
RF Amp
Varactor
Tuned Filter
Pin Diode
Antenna
Switch
RF Jack
Antenna
AGC
Control Voltage
from ASFIC
First LO
from FGU
Recovered Audio
Squelch
RSSI
IF IC
SPI Bus
16.8 MHz
Reference Clock
Second
LO VCO
2-4 THEORY OF OPERATION
Both the pre and post-RF amplifier varactor tuned filters have similar responses. The 3 dB
bandwidth of the filter is about 12 MHz. This enables the filters to be electronically controlled by
using a single control voltage which is DACRx.
The output of the post-RF amplifier filter is connected to the passive double balanced mixer which
consists of T3301, T3302, and CR3301. Matching of the filter to the mixer is provided by C3317,
C3318 and L3308. After mixing with the first LO signal from the voltage controlled oscillator (VCO)
using high side injection, the RF signal is down-converted to the 45.1 MHz IF signal.
The IF signal coming out of the mixer is transferred to the crystal filter (Y3200) through a resistor
pad (R3321 - R3323) and a diplexer (C3320 and L3309). Matching to the input of the crystal filter is
provided by C3200 and L3200. The crystal filter provides the necessary selectivity and
intermodulation protection.
3.2 Receiver Back-End
(
Refer to Figure 2-2 and the VHF Receiver Back End schematic diagram
)
The output of crystal filter Y3200 is matched to the input of IF amplifier transistor Q3200 by
capacitor C3203. Voltage supply to the IF amplifier is taken from the receive 5 volts (R5). The gain
controlled IF amplifier provides a maximum gain of about 10dB. The amplified IF signal is then
coupled into U3220 pin 3 via L3202, C3207, and C3230 which provides impedance matching for the
IF amplifier and U3220.
The IF signal applied to pin 3 of U3220 is amplified, down-converted, filtered, then demodulated to
produce the recovered audio at pin 27 of U3220. This IF IC is electronically programmable, and the
amount of filtering, which is dependent on the radio channel spacing, is controlled by the
microprocessor. Additional filtering, once externally provided by the conventional ceramic filters, is
replaced by internal filters in the IF module (U3220).
The IF IC uses a type of direct conversion process, whereby the externally generated second LO
frequency is divided by two in U3220 so that it is very close to the first IF frequency. The IF IC
(U3220) synthesizes the second LO and phase-locks the VCO to track the first IF frequency. The
second LO is designed to oscillate at twice the first IF frequency because of the divide-by-two
function in the IF IC.
In the absence of an IF signal, the VCO “searches” for a frequency, or its frequency will vary close to
twice the IF frequency. When an IF signal is received, the VCO will lock onto the IF signal. The
second LO/VCO is a Colpitts oscillator built around transistor Q3270. The VCO has a varactor
diode, D3270, to adjust the VCO frequency. The control signal for the varactor is derived from a loop
filter consisting of C3278 to C3280, R3274 and R3275.
The IF IC (U3220) also provides a received signal-strength indicator (RSSI) and a squelch output.
The RSSI is a dc voltage monitored by the microprocessor and is used as a peak indicator during
the bench tuning of the receiver front-end varactor filter. The RSSI voltage is also used to control the
automatic gain control (AGC) circuit at the front-end.
The demodulated signal on pin 27 of U3220 is also used for squelch control. The signal is routed to
U404 (ASFIC) where squelch signal shaping and detection takes place. The demodulated audio
signal is also routed to U404 for processing before going to the audio amplifier for amplification.
VHF Receiver (for all models except those with PCB8486473Z04) 2-5
3.3 Automatic Gain Control (AGC)
(
Refer to the Receiver Front End and Receiver Back End schematic diagrams
)
The front end automatic gain control circuit provides automatic reduction of gain of the front end RF
amplifier via feedback. This prevents overloading of backend circuits and is achieved by drawing
some of the output power from the RF amplifier output. At high radio frequencies, capacitor C3327
provides the low impedance path to ground for this purpose. CR3302 is a pin diode used for
switching the path on or off. A certain amount of forward biasing current is needed to turn the pin
diode on. Transistor Q3301 provides this current.
Radio signal strength indicator, RSSI, a voltage signal, is used to drive Q3301 to saturation i.e.
turned on. RSSI is produced by U3220 and is proportional to the gain of the RF amplifier and the
input power to the radio.
Resistors R3304 and R3305 are voltage dividers designed to turn on Q3301 at certain RSSI levels.
To turn on Q3301 the voltage across R3305 must be greater or equal to the voltage across R3324 +
Vbe. Capacitor C3209 is used to dampen any instability while the AGC is turning on. The current
flowing into the collector of Q3301, a high current gain NPN transistor, is drawn through the pin
diode to turn it on. Maximum current flowing through the pin is limited by resistors R3316, R3313,
R3306 and R3324. Feedback capacitor C3326 used to provide some stability to this high gain stage.
An additional gain control circuit is formed by Q3201 and associated components. Resistors R3206
and R3207 are voltage dividers designed to turn on Q3201 at a significantly higher RSSI level than
the level required to turn on pin diode control transistor Q3301. In order to turn on Q3201 the voltage
across R3207 must be greater or equal to the voltage across R3208 + Vbe. As current starts flowing
into the collector of Q3201, it reduces the bias voltage at the base of IF amplifier transistor Q3200
and in turn, the gain of the IF amplifier. The gain is then controlled in a range of -30dB up to +10dB.
2-6 THEORY OF OPERATION
4.0 Receiver (for models with PCB 8486473Z04)
Figure 2-3 VHF Receiver Block Diagram
4.1 Receiver Front-End
(
Refer to Figure 2-3 and the VHF Receiver Front End, VHF Receiver Back End and VHF Transmitter
schematic diagrams
)
The RF signal is received by the antenna and applied to a low-pass filter. For VHF, the filter consists
of L3531, L3532, C3532 to C3563. The filtered RF signal is passed through the antenna switch
consisting of two pin diodes (D3521 and D3551) and a pi network (C3531, L3551 and C3550).The
signal is then applied to a varactor tuned bandpass filter. The VHF bandpass filter comprises of
L3301, L3303, C3301 to C3304 and D3301. The bandpass filter is tuned by applying a control
voltage to the varactor diode (D3301) 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 Q3302 via C3306. After
being amplified by the RF amplifier, the RF signal is further filtered by a second varactor tuned
bandpass filter, consisting of L3305, L3306, C3311 to C3314 and D3302.
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
U3220
Receiver (for models with PCB 8486473Z04) 2-7
Both the pre and post-RF amplifier varactor tuned filters have similar responses. The 3 dB
bandwidth of the filter is about 12 MHz. This enables the filters to be electronically controlled by
using a single control voltage which is DACRx .
The output of the post-RF amplifier filter is connected to the passive double balanced mixer which
consists of T3301, T3302 and CR3301. Matching of the filter to the mixer is provided by C3317,
C3318 and L3308. After mixing with the first LO signal from the voltage controlled oscillator (VCO)
using high side injection, the RF signal is down-converted to the 44.85 MHz IF signal.
The IF signal coming out of the mixer is transfered to the crystal filter (Y3200) through a resistor pad
(R3321 - R3323) and a diplexer (C3320 and L3309). Matching to the input of the crystal filter is
provided by C3201 and L3200. The crystal filter provides the necessary selectivity and
intermodulation protection.
4.2 Receiver Back-End
(
Refer to Figure 2-3 and the VHF Receiver Back End schematic diagram
)
The output of crystal filter Y3200 is matched to the input of IF amplifier transistor Q3200 by L3203.
Voltage supply to the IF amplifier is taken from the receive 5 volts (R5). The IF amplifier Q3200 is
actively biased by a collector base feedback provided by R3202 and R3203. The gain controlled IF
amplifer provides a maximum gain of about 16dB. A dual hot carrier diode (CR3201) limits the filter
output voltage swing to reduce overdrive effects at RF levels above -27dBm. The amplified IF signal
is then coupled into U3220 (pin 1) via L3202, C3207, and C3200 which provides the matching for
the IF amplifier and U3220.
The IF signal applied to pin 1 of U3220 is amplified, down-converted, filtered, and demodulated, to
produce the recovered audio at pin 7 of U3220.
Within U3220, 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 2nd LO signal frequency is determined by
crystal Y3201. The second IF signal (455 kHz) is then filtered by an external ceramic filter Y3205
before being amplified by the second IF amplifier within U3220. Again, the signal is filtered by a
second external ceramic filter Y3203 or Y3204 depending on the selected channel spacing. Y3203
is used for 20/25 kHz channel spacing whereas Y3204, for 12.5 kHz channel spacing. The simple
circuit consisting of U3221, CR3202, CR3203 and resistors R3209, R3212, R3211 and R3205 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 U3220 (Pin 14).
The IF IC (U3220) contains a quadrature detector using a ceramic phase-shift element (Y3202) to
provide audio detection. Internal amplification provides an audio output level around 120mVrms
(@60% deviation) from pin 8 of U3220. This demodulated audio is fed to the ASFIC_CMP IC (U404)
in the controller section.
The IF IC (U3220) 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.
2-8 THEORY OF OPERATION
4.3 Automatic Gain Control (AGC)
(
Refer to the Receiver Front End and Receiver Back End schematic diagrams
)
The front end automatic gain control circuit provides automatic reduction of gain of the front end RF
amplifier via feedback. This prevents overloading of backend circuits and is achieved by drawing
some of the output power from the RF amplifier output. At high radio frequencies, capacitor C3327
provides the low impedance path to ground for this purpose. CR3302 is a pin diode used for
switching the path on or off. A certain amount of forward biasing current is needed to turn the pin
diode on. Transistor Q3301 provides this current.
Radio signal strength indicator, RSSI, a voltage signal, is used to drive Q3301 to saturation i.e.
turned on. RSSI is produced by U3220 and is proportional to the gain of the RF amplifier and the
input power to the radio.
Resistors R3304 and R3305 are voltage dividers designed to turn on Q3301 at certain RSSI levels.
To turn on Q3301 the voltage across R3305 must be greater or equal to the voltage across R3324 +
Vbe. Capacitor C3209 is used to dampen any instability while the AGC is turning on. The current
flowing into the collector of Q3301, a high current gain NPN transistor, is drawn through the pin
diode to turn it on. Maximum current flowing through the pin is limited by resistors R3316, R3313,
R3306 and R3324. Feedback capacitor C3326 used to provide some stability to this high gain
stage.
5.0 Frequency Generation Circuit
(
Refer to Figure 2-4 and the VHF Frequency Synthesizer schematic diagram
)
The Frequency Generation Circuit, shown in Figure 2-4, is composed of two main ICs, the
Fractional-N synthesizer (U3701), and the VCO/Buffer IC (U3801). Designed in conjunction to
maximize compatibility, the two ICs provide many of the functions that normally would require
additional circuits. The synthesizer block diagram illustrates the interconnect and support circuit
used in the region. Refer to the schematic for the reference designator.
Figure 2-4 VHF Frequency Generation Unit Block Diagram
The synthesizer is powered by regulated 5V and 3.3V which is provided from ICs U3711 and U3201
respectively. The 5V signal is supplied to pins 13 and 30 and the 3.3V signal is applied to pins 5, 20,
34 and 36 of U3701. The synthesizer in turn generates a superfiltered 5V which powers U3801.
Voltage
Multiplier
Synthesizer
U3701 Loop
Filter
VCOBIC
U3801
To
Mixer
To
PA Driver
VCP
Vmult1
Aux3
MOD Out
Modulating
Signal
Vmult2
Rx VCO Circuit
Tx VCO
TRB
16.8 MHz
Ref. Osc.
Rx Out
Tx Out
Circuit
Frequency Generation Circuit 2-9
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 (pins
7, 8 and 9) from the microprocessor, U409. A 3.3V dc signal from pin 4 indicates to the
microprocessor that the synthesizer is locked.
Transmit modulation from the ASFIC is supplied to pin10 of U3701. Internally the audio is digitized
by the Fractional-N and applied to the loop divider to provide low-port modulation. The audio runs
through an internal attenuator for modulation balancing purposes before going out at pin 41 to the
VCO.
5.1 Synthesizer
The Fractional-N Synthesizer, shown in Figure 2-5, uses a 16.8MHz crystal (Y3761) to provide a
reference for the system. The LVFractN IC (U3701) further divides this to 2.1MHz, 2.225MHz, and
2.4MHz as reference frequencies. Together with C3761, C3762, C3763, R3761, and D3761, they
build up the reference oscillator that is capable of 2.5 ppm stability over temperatures of -30 to 85°C.
A 16.8MHz signal at pin 19 of U3701 is also provided for use by ASFIC and LVZIF (for all models
except those with PCB8486473Z04).
The loop filter which consist of C3721, C3722, R3721, R3722 and R3723 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 U3701 to put the synthesizer within 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
made up of C3701 to C3704 and triple diodes D3701, D3702. Two 3.3V square waves (180 degrees
out of phase) are first multiplied by four and then shifted, along with regulated 5V, to build up 13.5V
at pin 47 of U3701.
Figure 2-5 VHF Synthesizer Block Diagram.
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)
MOD IN (U404 PIN 40)
+5V (U3711 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 PA
)
FREF (U3220 PIN 21 & U404 PIN 34)
39
BIAS2
41
DUAL
TSTRS
48
5V
R5
5, 20, 34, 36
(U3201 PIN 5)
AUX1
VDD, 3.3V MODOUT
U3701
LOW VOLTAGE
FRACTIONAL-N
SYNTHESIZER
2-10 THEORY OF OPERATION
5.2 Voltage Controlled Oscillator (VCO)
(
Refer to Figure 2-6 and the VHF Voltage Controlled Oscillator schematic diagram)
The VCOB IC (U3801), shown in Figure 2-6, in conjunction with the Fractional-N synthesizer
(U3701) generates RF in both the receive and the transmit modes of operation. The TRB line
(U3801 pin 19) determines which oscillator and buffer are enabled. A sample of the RF signal from
the enabled oscillator is routed from U3801 pin 12, through a low pass filter, to the prescaler input
(U3701 pin 32). After frequency comparison in the synthesizer, a resultant CONTROL VOLTAGE is
received at the VCO. This voltage is a DC voltage typically between 3.5V and 9.5V when the PLL is
locked on frequency.
Figure 2-6 VHF VCO Block Diagram
Presc
RX
TX
Matching
Network Low Pass
Filter
Attenuator
Pin8
Pin14
Pin10
(3701 Pin28)
VCC Buffers
TX RF Injection
U3701 Pin 32
AUX3 (U3701 Pin2)
Prescaler Out
Pin 12
Pin 19
Pin 20
TX/RX/BS
Switching Network
U3801
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
(U3701 Pin28)
Rx-SW
Tx-SW
Vcc-Logic
(U3701 Pin28)
Steer Line
Voltage
(VCTRL)
Pin13
Pin3
TRB_IN
LO RF INJECTION
Frequency Generation Circuit 2-11
In the receive mode, U3801 pin 19 is low or grounded. This activates the receive VCO by enabling
the receive oscillator and the receive buffer of U3801. The RF signal at U3801 pin 8 is routed
through a matching network. The resulting LO RF INJECTION signal is applied to the mixer at
T3302.
During the transmit condition, when PTT is pressed, 3.2 volts is applied to U3801 pin 19. This
activates the transmit VCO by enabling the transmit oscillator and the transmit buffer of U3801. The
RF signal at U3801 pin 10 is injected into the input of the PA module (U3501 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 U3701, pin 41.
When a high impedance is applied to U3801 pin19, 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 2-1 Level Shifter Logic
Desired
Mode AUX 4 AUX 3 TRB
Tx n.u. High (@3.2V) High (@3.2V)
Rx n.u. Low Low
Battery Saver n.u. Hi-Z/Float
(@1.6V)
Hi-Z/Float (@1.6V)
2-12 THEORY OF OPERATION
6.0 Voice Storage (GP1280)
(
Refer to Figure 2-7 and the VHF Voice Storage schematic diagram)
The Voice Storage feature is offered as standard in the GP1280 and as an Option board for
GP340/GP360/GP380 and GP640/GP680.
The Voice Storage feature enables users to:
■Record and Playback Personal Memo (Reminders, Notes, etc.).
■Send over-the-air an “Out-Of-Office” message when an incoming call is received but is not
available to take up call.
■Over-the-air recording of important voice message being received.
Figure 2-7 Audio path for voice storage connection to interface connector
VCCD
VSSA1
VSSA2
VSSA3
VSSD
XCLK
SCLK
SS
VCCA
MOSI
AMCAP
ANA_NEG
ANA_POS
AUDOUT
MISO
U700
ISD33000
C701 C702
1uF
100pF
C703
0.1uF
CR700
Vddd
C704
0.1uF
CLK
MISO
DATA
VS_CS
R701
18K
R702
18K
C707
0.1uF
U710-2
MC74HC4066
CNTL
VDD
VSS
560K
R708
Vddd
0.1uF
C719
RX_AUD_RTN
VS_GAINSEL
C713
0.1uF
FLAT_RX_SND
CNTL
VDD
VSS
U710-3
MC74HC4066
CNTL
VDD
VSS
U710-1
MC74HC4066
C715
0.1uF
EXT_MIC
U710-4
MC74HC4066
CNTL
VDD
VSS
VS_AUDSEL
C718
1000pF
R707
LM2904
U720-2
R706
56K
5.1K
.01uF
C711
1MEG
R709
C717
0.1uF
R710
470K
SWB+
Vddd
0.1uF
C714
R717
10K
R716
1.8K
LM2904
U720-1
C710
33uF
C705
0.1uF
Vddd
0.1uF
C708
1000pF
C709
Voice Storage (GP1280) 2-13
Audio routing to the Voice Storage circuitry during receive message recording, message playback,
personal memo recording and voice prompt transmit over the air are as follows:
Received Message Recording
The receive audio is tapped from the Rx_Aud_Rtn pin of the ASFIC_CMP during receive mode.
Message Playback
Message playback is via the FLAT_RX_SND pin of ASFIC_CMP. In the ASFIC_CMP, the signal is
routed via the Side-Tone path to the Receive path where playback audio is routed to the speaker.
Personal Memo Recording
In this mode, voice is pick-up at the Mic. and via the Side-Tone path will be directed to the
Rx_Aud_Rtn pin, which is then routed to the voice recording chip.
Voice Prompt transmit over the air
A personal voice prompt or Out-Of-Office Message which is stored in the IC can be transmitted over
the air through mic path in the ASFIC_CMP to the calling party. This feature is similar to the
Telephone Answering Machine feature when the person called is not available to attend the call.
2-14 THEORY OF OPERATION
Chapter 3
TROUBLESHOOTING CHARTS
1.0 Troubleshooting Flow Chart for Receiver, for all models except
those with PCB 8486473Z04 (Sheet 1 of 2)
Activity
on U3220
LVZIF_SEL
pin?
16.8 MHz
at pin 21
U3220?
Check 2nd LO Control Voltage at C3279
Audio
at pin 27 of
U3220?
VCO
locked?
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Check Controller
Ye s
No
Spray of inject 1st IF into
XTAL Filter
IF Freq: 45.1MHz
Audio
heard?
B
Yes
No
B
Yes
Check FGU
No
No
A
A
Yes
Check Q3270 bias
circuitry for faults.
Rotate Freq. Knob
Check controller
Before replacing U3220, check 2nd
VCO Q3270. Check VCO O/P level,
C3272, C3273.
Ye s
No
3-2 TROUBLESHOOTING CHARTS
Troubleshooting Flow Chart for Receiver for all models except those
with PCB 8486473Z04 (Sheet 2 of 2)
Q3200
collector OK?
IF signal
present?
RF
Signal
at C3306
?
RF
Signal
at C3302
?
RF
Signal
at R3313
?
IF Signal
at C3200?
Check filter between
C3302 & C3306; program
filter to schematic test freq
and check varactor
voltages. Check Q3721, U3701
(pin 48) voltages
and U3711
Check harmonic filters L3531 & L3532,
C3532 and ant. switches D3521, D3551,
L3551, R3551,C3551, C3552, L3552.
Is R5
present
?
Trace IF signal
from C3200 to
Q3200. Check for
bad XTAL filter.
No
RF
Signal
at T3301
?
No
No
No or
Inject RF into J3501
Are
varactor
voltages
OK
?
No
Yes
Check RF amp
(Q3302) Stage.
Check filter between
C3313 & T3301.
Yes
Check T3301, T3302, CR3301,
R3321, R3322, R3320
Yes
1st LO O/P
OK?
Locked?
Yes
Check FGU
Yes
No
Yes Yes
Check for 2.9
VDC
No
No
No
Check U404 voltage. U404
can be selected by MCU
before replacing U404.
Check varactor filter.
No
Yes
Yes
Yes
A
A
B
weak RF
Before replacing
U3220, check
U3220 voltages;
trace IF signal
path.
Troubleshooting Flow Chart for Receiver, for models with PCB 8486473Z04 (Sheet 1 of 2) 3-3
2.0 Troubleshooting Flow Chart for Receiver, for models with PCB
8486473Z04 (Sheet 1 of 2)
Bad SINAD
Bad 20dB Quieting
No Recovered Audio
START
Audio at pin
8 of U3220?
Check Controller
(in the case of no audio)
OR ELSE go to “B”
Yes
No
Spray or inject 44.85MHz
into XTAL Filter Y3200
Audio heard?
B
Yes
No
Check 2nd LO
(44.395MHz) at C3274
LO Present?
B
Yes
Voltages
ok?
Biasing ok?
Check circuitry
around U3220.
Replace U3220
if defect
No
No
A
Yes
Check Q3200 bias
for faults.
Replace Q3200.
Go to B
Yes
No
Check voltages on
U3220
Check circuitry
around Y3202.
Replace Y3202
if defect
3-4 TROUBLESHOOTING CHARTS
Troubleshooting Flow Chart for Receiver, for models with PCB
8486473Z04 (Sheet 2 of 2)
IF Signal at
L3200?
No
RF Signal at
T3301?
RF Signal at
R3313?
No
RF Signal at
C3306?
No
RF Signal at
C3302?
No or
Check harmonic filter L3531 & L3532,
C3532 and ant. switches D3521, D3551,
L3551, R3551, C3551, C3552, L3552
Check filter between
C3302 & C3306; pro-
gram filter to schematic
test freq and check
varactor voltages.
Inject RF into J3501
Are varactor
voltages OK?
No
Yes
Check RF amp (Q3302)
Stage.
Check filter between
C3313 & T3301.
Yes
Check T3301, T3302,
CR3301, R3321, R3322,
R3323
Yes
1st LO O/P
OK?
Locked?
Yes
Check FGU
Yes
Trace IF signal
from L3200 to
Q3200. Check for
bad XTAL filter.
No
Yes Q3200 collec-
tor OK?
IF signal
present?
Before replacing
U3220, check
U3220 volt-
ages; trace IF
signal path.
Yes
Check for 2.9
VDC
Is R5
present?
Check Q3721,
U3701 (pin 48) volt-
ages and U247
No
No
No
Check U404 voltage and if
U404 can be selected by
MCU before replacing
U404.
Check varactor filter.
No
Yes
Yes
Yes
A
A
B
weak RF
Troubleshooting Flow Chart for Transmitter 3-5
3.0 Troubleshooting Flow Chart for Transmitter
Is
Control Voltage High
or Low at TP3502
?
Is
There
B+ Bias for
Ant switch
D3521
?
START
No Power
Check Q3561
Is
Current
OK?
Check PCIC
1. Check Pin Diodes
2. Check Harmonic Filter
Inspect/Repair Tx.
Output Network
Is
Power
OK?
Done
Check Drive to
Module
Is Drive
OK
?
Troubleshoot VCO
Inspect PA Network/
Check Power Out of
U3501 at Cap C3512
Is
Power
OK?
Replace U3501
Is
Power OK
?
Replace Q3501
Done
Done
No
Yes
Yes No
No
Yes
Low
High
No
Yes
Yes No
Yes
No
3-6 TROUBLESHOOTING CHARTS
4.0 Troubleshooting Flow Chart for Synthesizer
5V
at pin 6 of
D3701
Is
information
from mP U409
correct
?
Is
U3701 Pin
18 AT 4.54
VDC?
Is U3701
Pin47 AT = 13
VDC
Is
U3701
Pin 19<0.7 VDC
in RX & >4.3 VDC
in TX?
Start
Visual
check of the
Board
OK?
Correct
Problem
Check 5V
Regulator
+5V
at U3701
Pin’s
13 & 30?
Is
16.8MHz
Signal at
U3701 Pin
19?
Check Y3761,
C3761, C3762,
C3763, D3761 &
R3761
Are
signals at
Pin’s 14 &15
of U3701
?
Check
L3701,
R3701
Check Q260,
Q261 & R260
U3701
pin 2 at >3V
in Tx and
<0.7V in
Rx
Remove
Shorts
Is
there a short
between Pin 47 and
Pins 14 & 15 of
U3701?
Replace or
resolder
necessary
components
Is RF level at
U3701 Pin 32
>-30 dBm?
Are
C3721,
C3722,C3723,
R3721, R3722,
R3723
OK?
Replace
U3701
If R3727, C3726 & C3727
are OK, then see VCO
troubleshooting chart
Are
Waveforms
at Pins 14 & 15
triangular?
Do
Pins 7,8 & 9
of U3701 toggle
when channel
is changed
?
Check prgramming
lines between U409
and U3701
Pins 7,8 & 9
Replace
U3701
Check uP U409
Troubleshooting
Chart
NO
YES
NO
YES
NO
YES
NO
YES
NO
NO
NO
YES
YES
NO
YES
YES
NO
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
YES
Check D3701,
D3702, U3701,
C3701 - C3707
3.3V
at U3701
pins 5, 20,
34 & 36
Is
16.8MHz
signal at
U3701 pin
23?
Replace
U3701
YES
NO
NO
YES
NO
YES
Replace
Check
U3201,
L3731
Troubleshooting Flow Chart for VCO 3-7
5.0 Troubleshooting Flow Chart for VCO
L3821,
L3822,
L3823,
O/C?
AUX 3 at
U3701
High?
U3801
Pin 19 =0V
AUX 3 at
U3701
High?
L3831,
L3832
L3833
O/C?
U3801
Pin 10
>1V?
Tx
Carrier?
VCTRL
0V or
13V?
START
No LO?
VCO OK
Check
R3829
TRB = 3.2V
Change L3831,
L3832
Change
U3801
Check U3701
Pin 2 for 3.2V
Change
U3701
Change
L3821,L3822,
L3823, L3825
Change
U3801
Change
U3801
Check for faulty parts
or dry joints of L3812,
C3806, R3806,
R3802, & L3801
A
A
No
No
Yes
Yes
Yes No
No
Yes
Yes
Yes
No
Yes
No
No
Yes Yes
No
No
Check R3811,
L3811 for dry
joint or faulty
No
Yes
3-8 TROUBLESHOOTING CHARTS
6.0 Troubleshooting Flow Chart for Receive Message/Personal
Memo Recording
Cannot Receive
Message
Check menu
whether record
incoming messages
turned on
Personal Memo
Recording
Check J400-34
Any audio?
Check keypad/
controller flex
interconnect
ok?
Assemble
properly
Change U700 or Voice
Storage option board
Turn on
“Record Incoming
Call”
Check Mic I/P at
J403-18 any audio?
Check Spkr/Mic
Flex Connection
J403
No
Yes
Yes
Yes
No
Yes
No
Troubleshooting Flow Chart for Message Playback 3-9
7.0 Troubleshooting Flow Chart for Message Playback
Cannot Playback
Message
Check keypad/
controller flex
interconnect ok?
Audio at J400-35?
Change U700 or
Voice Storage
Option Board
Change U404
No
Yes
Yes
No
Assemble
properly
3-10 TROUBLESHOOTING CHARTS
Chapter 4
VHF PCB/SCHEMATICS/PARTS LISTS
1.0 Allocation of Schematics and Circuit Boards
1.1 Controller Circuits
The VHF circuits are contained on the printed circuit board (PCB) which also contains the Controller
circuits. This Chapter shows the schematics for the VHF circuits only, refer to the Controller section
for details of the related Controller circuits . The PCB component layouts and the Parts Lists in this
Chapter show both the Controller and VHF circuit components. The VHF schematics and the related
PCB and parts list are shown in the tables below.
1.2 Voice Storage Facility
The Voice Storage facility is fitted to the GP1280 radio as standard and the schematics, component
layout and parts list for these circuits are shown in this Chapter. The Voice Storage facility may be
fitted to other radios in the GP Series as an option board; reference must be made to the Option
Board manual in this case. The Voice Storage schematic and the related PCB is shown in Tables
4-2 and 4-4 below.
Table 4-1 VHF Diagrams and Parts Lists
PCB :
8486062B12 Main Board Top Side
8486062B12 Main Board Bottom Side
8486062B14 Main Board Top Side
8486062B14 Main Board Bottom Side
Page 4-5
Page 4-6
Page 4-25
Page 4-26
SCHEMATICS
Controls and Switches
Receiver Front End
Receiver Back End
Synthesizer
Voltage Controlled Oscillator
Transmitter
Page 4-7
Page 4-8
Page 4-9
Page 4-10
Page 4-11
Page 4-12
Parts List
8486062B12
8486062B14
Page 4-13
Page 4-27
4-2 VHF PCB/SCHEMATICS/PARTS LISTS
Table 4-2 VHF GP1280 Diagrams and Parts Lists
PCB :
8486101B09 Main Board Top Side
8486101B09 Main Board Bottom Side
8486101B10 Main Board Top Side
8486101B10 Main Board Bottom Side
Page 4-17
Page 4-18
Page 4-31
Page 4-32
SCHEMATICS
Controls and Switches
Receiver Front End
Receiver Back End
Synthesizer
Voltage Controlled Oscillator
Transmitter
Voice Storage Circuits
Page 4-7
Page 4-8
Page 4-9
Page 4-10
Page 4-11
Page 4-12
Page 4-19
Parts List
8486101B09
8486101B10
Page 4-21
Page 4-33
Table 4-3 VHF Diagrams and Parts Lists
PCB :
8486062B16 Main Board Top Side
8486062B16 Main Board Bottom Side
8486062B17 Main Board Top Side
8486062B17 Main Board Bottom Side
Page 4-37
Page 4-38
Page 4-49
Page 4-50
SCHEMATICS
Controls and Switches
Receiver Front End
Receiver Back End
Synthesizer
Voltage Controlled Oscillator
Transmitter
Page 4-39
Page 4-40
Page 4-41
Page 4-42
Page 4-43
Page 4-44
Parts List
8486062B16
8486062B17
Page 4-45
Page 4-51
Allocation of Schematics and Circuit Boards 4-3
Table 4-4 VHF GP1280 Diagrams and Parts Lists
PCB :
8486101B11 Main Board Top Side
8486101B11 Main Board Bottom Side
Page 4-55
Page 4-56
SCHEMATICS
Controls and Switches
Receiver Front End
Receiver Back End
Synthesizer
Voltage Controlled Oscillator
Transmitter
Voice Storage Circuits
Page 4-39
Page 4-40
Page 4-41
Page 4-42
Page 4-43
Page 4-44
Page 4-19
Parts List
8486101B11 Page 4-57
Table 4-5 VHF Diagrams and Parts Lists
PCB :
8486473Z04 Main Board Top Side
8486473Z04 Main Board Bottom Side
Page 4-61
Page 4-62
SCHEMATICS
Controls and Switches
Receiver Front End
Receiver Back End
Synthesizer
Voltage Controlled Oscillator
Transmitter
Page 4-63
Page 4-64
Page 4-65
Page 4-66
Page 4-67
Page 4-68
Parts List
8486473Z04 Page 4-69
4-4 VHF PCB/SCHEMATICS/PARTS LISTS

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