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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...
MODEL CHART AND TECHNICAL SPECIFICATIONS GP140 Model Chart Professional GP140 (UHF) Model Description MDH25RDC9AA3_E GP140 UHF 403-470 MHz 4W 16 Ch Item Description PMLE4130_ *GP140 UHF Back Cover Kit 6864110B25 GP140 Basic User Guide NAE6483_ UHF Whip (403-470 MHz) Antenna HNN9008_ Battery, NiMH Standard x = Indicates one of each is required.
GP1280 Model Chart GP1280 Model Chart Professional GP1280 (UHF) Model Description MDH25RDN9CK8_E GP1280 UHF 403-470 MHz 4W Item Description PMLE4142_ *GP1280 UHF Back Cover Kit 6864110B20 GP1280 Basic User Guide NAE6483_ UHF Whip (403-470 MHz) Antenna HNN9008_ Battery, NiMH Standard x = Indicates one of each is required.
Chapter 2 THEORY OF OPERATION Introduction This Chapter provides a detailed theory of operation for the UHF 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.
THEORY OF OPERATION The LDMOS PA is capable of supplying an output power of 7W with an input signal of 0.3W. The current drain is typically 1300mA while operating in the frequency range of 403-470MHz. The power output can be varied by changing the bias voltage. 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 and R170).
UHF Receiver UHF Receiver The UHF receiver consists of a front end, back end, and automatic gain control circuits. A block diagram of the receiver is shown in Figure 2-2. Detailed descriptions of these features are contained in the paragraphs that follow. Antenna Pin Diode Varactor...
THEORY OF OPERATION 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.
UHF Receiver Automatic Gain Control (AGC) (Refer to the UHF 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 action is necessary to prevent overloading of backend circuits. This is achieved by drawing some of the output power from the RF amplifier output.
THEORY OF OPERATION Frequency Generation Circuit (Refer to Figure 2-3 and the UHF Frequency Synthesizer schematic diagram) The frequency generation circuit, shown in Figure 2-3, is composed of Fractional-N synthesizer U201 and VCO/Buffer IC U241. Designed in conjunction to maximize compatibility, the two ICs provide many of the functions that normally require additional circuitry.
Frequency Generation Circuit Synthesizer (Refer to Figure 2-4 and the UHF Synthesizer schematic diagram) The Fractional-N synthesizer, shown in Figure 2-4, uses a 16.8MHz crystal (FL201) to provide a reference for the system. The LVFractN IC (U201) further divides this to 2.1MHz, 2.225MHz, and 2.4MHz to be used as reference frequencies.
THEORY OF OPERATION Voltage Controlled Oscillator (VCO) (Refer to Figure 2-5 and the UHF Voltage Controlled Oscillator schematic diagram) The VCOB IC (U241), shown in Figure 2-5, 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 are enabled.
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Frequency Generation Circuit Table 2-1 Level Shifter Logic Desired AUX 4 AUX 3 Mode High (@3.2V) High (@4.8V) High Battery Saver Hi-Z/Float (@2.5V) In the 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.
2-10 THEORY OF OPERATION Voice Storage (GP1280 Only) (Refer to Figure 2-6 and the UHF 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 models. The Voice Storage feature enables users to: Record and Playback Personal Memo (Reminders, Notes, etc.).
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Voice Storage (GP1280 Only) 2-11 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.
Chapter 3 TROUBLESHOOTING CHARTS Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) START Bad SINAD Bad 20dB Quieting No Recovered Audio udio Check Controller at pin 27 of U301? Spray of inject 1st IF into XTAL Filter IF Freq: 45.1MHz Check Q320 bias circuitry for faults.
TROUBLESHOOTING CHARTS Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) Inject RF into J101 Q302 Trace IF signal collector OK? IF Signal from L311 to IF signal at L311? Q302. Check for present? bad XTAL filter. Before replacing U301, check U301 voltages;...
Troubleshooting Flow Chart for Transmitter Troubleshooting Flow Chart for Transmitter START No Power Is There B+ Bias for Check Q111 Ant switch CR101 Is Current Check PCIC Is Control Voltage High or Low at C119 High 1. Check Pin Diodes Check Drive to 2.
Chapter 4 UHF PCB/SCHEMATICS/PARTS LISTS Allocation of Schematics and Circuit Boards Controller Circuits The UHF circuits are contained on the printed circuit board (PCB) which also contains the Controller circuits. This Chapter shows the schematics for the UHF 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 UHF circuit components.
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UHF PCB/SCHEMATICS/PARTS LISTS Table 4-2 UHF GP1280 Diagrams and Parts Lists PCB : 8480587Z01 Main Board Top Side Page 4-15 Main Board Bottom Side Page 4-16 SCHEMATICS Controls and Switches Page 4-5 Receiver Front End Page 4-6 Receiver Back End Page 4-7 Synthesizer Page 4-8...
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Allocation of Schematics and Circuit Boards Table 4-4 UHF Diagrams and Parts Lists PCB : 8480450Z13/14 Main Board Top Side Page 4-31 Main Board Bottom Side Page 4-32 SCHEMATICS Controls and Switches Page 4-33 Receiver Front End Page 4-34 Receiver Back End Page 4-35 Synthesizer Page 4-36...