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Ritron DR-142 Operating And Service Manual

Programable vhf fm receiver module
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PRELIMINARY
DR-142
PROGRAMABLE VHF FM RECEIVER MODULE
OPERATING AND SERVICE MANUAL
RITRON INC.
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Summary of Contents for Ritron DR-142

  • Page 1 PRELIMINARY DR-142 PROGRAMABLE VHF FM RECEIVER MODULE OPERATING AND SERVICE MANUAL RITRON INC.

  • Page 2: Table Of Contents

    Precautions for handling CMOS Synthesizer shield DESCRIPTION OF INPUT/OUTPUT PROGRAMMING THE RADIO PROGRAMMING THE RADIO USING A PC COMPUTER Programmable Features COMPUTER SOFTWARE COPYRIGHTS DR-142 THEORY OF OPERATION INTRODUCTION POWER SUPPLY AND VOLTAGE DISTRIBUTION REFERENCE OSCILLATOR SYNTHESIZER RECEIVER Receiver Front End...

  • Page 3: Dr-142 Specifications

    DR-142 SPECIFICATIONS FCC ID: AIERIT17-142R FCC Rule Parts: Frequency Range: 136-156 MHz or 154-174 MHz RF Channels: 8 Independent RX frequencies Synthesizer Step Size: 5 kHz Frequency Stability: +/-2.5 PPM (-30 to +50 C) Tone/Code Signaling: CTCSS (Quiet Call) and DCS...

  • Page 4: Sub-D 15 Pin Connector

    >700 mW into 8 Ω, with less than 5 % THD Audio Output Sub D 15 Pin Connector The DR-142 is equiped with a 15 pin female sub D connector with the following functions: Pin# Function least significant channel select bit (CS0)

  • Page 5: General

    RITRON, this would be no problem since an FCC label is affixed to the bottom of the PC board. If the DR-142 is to be installed in an enclosure, the installer must ensure that either the FCC label on the unit is visible through a door, window or other opening, or add a label to the outside of the enclosure.

  • Page 6: Synthesizer Shield

    5) Power/voltage transients - Do not insert or remove CMOS devices with power applied. Check all power supplies to be used for testing CMOS devices, making sure that no voltage transients are present. 6) Soldering - Use a grounded soldering iron for soldering CMOS circuitry. 7) Lead-straightening tools - When straightening CMOS leads, provide ground straps for the tool used.

  • Page 7: Description Of Input/Output

    CTCSS or DCS tone is present the radio will unsquelch the SPEAKER and AUX_OUT lines. Programming Port (pin 9) This line is a bi-directional programming port to be connected to a RITRON programming cable. The other end of the programming cable connects to the PC’s serial port 25 pin D-sub connector. The appropriate DR-142 programming software must be run for configuring the transceiver.

  • Page 8: Programming The Radio

    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.

  • Page 9: Dr-142 Theory Of Operation

    POWER SUPPLY AND VOLTAGE DISTRIBUTION The DR-142 is powered by an 8 to 15 VDC external power supply. F601 is a 3A fuse in series with J301 for short circuit protection. Zener diode D601 prevents over voltage damage by blowing the F601 fuse when over 18 volts is applied.

  • Page 10: Receiver

    Two types of squelch circuits exist on the DR-142, an RSSI squelch and a noise squelch. Both types can be used simultaneously or one or the other can be used. The RSSI (receive signal strength indicator) squelch, which is typically set around –110 dBm, must be set to open at a higher level than the...

  • Page 11: Microcontroller

    RESET is held low to start the radio in a known state on power up. 30, 31 SERIAL DATA PORT links the microcontroller to communications from an external data terminal via programming port pin 9 of J301. This allows programming of the DR-142 EE memory used to store channel frequency and configuration information.

  • Page 12: Dr-142 Alignment Procedure

    RECEIVER FRONT END TUNNING The DR-142 receiver is factory tuned for a frequency range of 136 to 156 MHz (low split) or 154 to 174 MHz (high split). If receiver appears to be less sensitive on one of the band edges the front end tuning coils may need readjustment.

  • Page 13: Receiver Squelch

    RECEIVER SQUELCH The DR-142 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 –118 or greater.

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