DR-142 and DR-442 PROGRAMABLE FM RECEIVER MODULE OPERATING AND SERVICE MANUAL RITRON INC.
TABLE OF CONTENTS SECTION TOPIC PAGE 1. DR-142/442 SPECIFICATIONS SUB-D 15 PIN CONNECTOR 2 3 2. INTRODUCTION GENERAL Model Identification FCC ID Unauthorized Modifications 4 4 4 4 MAINTENANCE INFORMATION Surface Mount Repairs Precautions for handling CMOS Synthesizer shield 4 4 4 5 3. DESCRIPTION OF INPUT/OUTPUT 6 4. PROGRAMMING THE RADIO PROGRAMMING THE RADIO USING A PC COMPUTER Programmable Features COMPUTER SOFTWARE COPYRIGHTS 7 7 7 7 5.
DR-142/442 Specifications FCC ID: DR-142 AIERIT17-142R DR-442 AIERIT17-442R Frequency Range: 136-156 MHz or 154-174 MHz 400-420 MHz or 450-470 MHz Bandwidth: 20 MHz 20 MHz Synthesizer Step Size: 2.5 kHz 6.25 kHz FCC Rule Parts: 15 RF Channels: 8 Independent RX frequencies Frequency Stability: +/-2.5 PPM (-30°C to +60°C) Tone/Code Signaling: CTCSS (Quiet Call) and DCS Maximum Data rate: 9600 bps with 4-level FSK Power Supply: RX Standby Current: Dimensions: Weight: 8 to 16.
Sub D 15 Pin Connector The DR-142/442 is equiped with a 15 pin female sub D connector with the following functions: Pin# 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Function least significant channel select bit (CS0) channel select 1 (CS1) Most significant channel select (CS2) N/A N/A + 8 to 16.
Surface Mount Repair RITRON surface mount products require special equipment and servicing techniques. Improper servicing techniques can cause permanent damage to the printed circuit boards and/or components, which is not covered by RITRON’s warranty. If you are not completely familiar with surface mounted component repair techniques, RITRON recommends that you defer maintenance to qualified service personnel.
DESCRIPTION OF INPUT/OUTPUT Channel Select (pins 3,2,1) Three lines control the channel selection; CS2, CS1, CS0. The inputs have binary weighting of 4, 2 and 1 respectively. Tying an input to ground gives it a zero weighting. Thus, if no inputs are tied low channel eight is selected. In this case the 111 in binary or 7 in decimal is the eighth channel. 000 would be channel 1. Power Input (pin 6) A power source of 8 to 16.7 VDC with 0.5 Amp capability should be connected here.
Carrier Detect Output (pin 13) This line will be pulled to 5 volts through a 390 ohm resistor when a carrier is present.
PROGRAMMING THE RADIO USING A PC COMPUTER RITRON’s programming kit, DTXL-PCPK-2.0, allows programming of the DR-142/442 model radios using a PC compatible computer. The PC Programming Kit Includes: 1) Ritron Transceiver programming software, DTXL-PCPS-2.0, which is contained on 3.5" diskettes. 2) Ritron PC to radio adapter cable, 9/RTC-PAS, which is terminated at one end with a DB-25F connector, at the other end with a 6 pin modular plug.
DR-142/442 THEORY OF OPERATION INTRODUCTION The DR-142/442 is an eight-channel synthesized receiver unit capable of data reception at rates up to 9600 bps when using 4-level FSK. The unit maintains under 20 mA current consumption at 13.8 VDC when in the receive standby mode. The current drain goes up as the voltage goes down. POWER SUPPLY AND VOLTAGE DISTRIBUTION The DR-142/442 is powered by an 8 to 16.7 VDC external power supply. F601 is a 3A fuse in series with J301 for short circuit protection.
RECEIVER Receiver Front End The signal from the antenna passes through the transmitter low pass filter and then goes to the tunable bandpass filter L101 and L102 for VHF or L101, L102, L107 and L108 for UHF. Q101 amplifies the signal about 13 dB before going through another band pass filter and mixer matching stage. The receiver is turned on by Q107 and Q108 supplying RX_5v when RXEN of U301 goes high. The amplified received input signal is applied to the base of mixer Q102.
DR-142/442 THEORY OF OPERATION MICROCONTROLLER The DR-142/442 receiver is electronically controlled by U301, an 8-bit flash programmable microcontroller. U301 has A/D inputs and PWM outputs for processing analog signals. Radio characteristics are stored in internal EE memory. Its RS232 port is used in programming the radio’s personal characteristics such as frequencies and tones. PIN 1 2 3 4 5 6 7 8 9 10 11 12 13 14 DESCRIPTION N/A N/A GROUND +5 VDC VCC supply voltage.
DR-142/442 ALIGNMENT PROCEDURE An authorized RF service technician must perform test and alignment of the DR-142/442. Do not attempt service of the DR-142/442 if not completely familiar with frequency synthesized radio operation. RECOMMENDED TEST EQUIPMENT 1) 0 to +15 VDC, 0.
RECEIVER SQUELCH The DR-142/442 is capable of two squelch operating modes. Also, both can operate simultaneously. See the theory above. The units can be configured as the user requires. When a low level signal appears the noise squelch opens when the carrier level with 1.5 kHz (3.0 kHz for wideband) deviation is –122 dBm or greater. When the signal appearing is –108dBm or greater the RSSI squelch opens the audio with an even faster attack time. The above levels are factory set levels.
