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All Weather Inc 1793 User Manual

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Model 1793

VHF Radio

FAA APPROVED
ECP232 — 2017 Jul 28
NOT FAA APPROVED
All Weather Inc. • 1165 National Drive • Sacramento, CA 95834 • USA • 800.824.5873 • www.allweatherinc.com
User's
Manual
Rev. A

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  • Page 1: Vhf Radio

    Model 1793 VHF Radio User’s Manual FAA APPROVED ECP232 — 2017 Jul 28 NOT FAA APPROVED Rev. A All Weather Inc. • 1165 National Drive • Sacramento, CA 95834 • USA • 800.824.5873 • www.allweatherinc.com...
  • Page 2 Copyright © 2016, All Weather, Inc. All Rights Reserved. The information contained herein is proprietary and is provided solely for the purpose of allowing customers to operate and/or service All Weather, Inc. manufactured equipment and is not to be released, reproduced, or used for any other purpose without written permission of All Weather, Inc.

  • Page 3: Table Of Contents

    1793 VHF Radio User's Manual TABLE OF CONTENTS 1. INTRODUCTION ......................... 1 1.1 Description ..........................1 2. INSTALLATION AND CHECKOUT ..................1 2.1 Setting the Transmitter Frequency ....................1 2.2 Mounting Bracket ........................3 2.3 Connections ..........................5 2.4 Calibration ..........................7 2.5 Operational Check ........................

  • Page 4: Introduction

    11.25 to 16.25 volts. 1.1 DESCRIPTION Each Model 1793 VHF Radio consists of a transmitter board mounted in a heat sink as shown in Figure 1. The transmitter is a low power VHF AM transmitter which can transmit on a single programmable synthesized frequency, with 25 kHz channel spacing in the frequency range of 118.000 to 136.975 MHz.

  • Page 5: Installation And Checkout

    DS401 and DS402 shown in Error! Reference source not found. and Figure 3. Refer to Figure 4 for the frequency selection switch settings. Fine-tuning the frequency is achieved by adjusting C427. Figure 2. Adjustments and Frequency Setting Jumpers Figure 3. Model 1793 Bottom View...
  • Page 6 1793 VHF Radio User's Manual Figure 4. Frequency Selection Switch Map...

  • Page 7: Mounting Bracket

    1793 VHF Radio User's Manual 2.2 MOUNTING BRACKET The CDP rack’s bottom shelf (Figure 5) is fixed in place. Components are accessible through the rack’s front or side doors. The VHF radio is secured to the bottom side of the sliding top shelf using four wing knobs facing up when the VHF radio is viewed from the front end of the CDP rack.
  • Page 8 1793 VHF Radio User's Manual The mounting bracket and the VHF radio are installed at the factory. Should the need arise to remove the radio, undo the four wing knobs on either side of the radio. Because of the tight space inside the CDP rack, it is recommended that any connecting cables remain in place until the VHF radio is removed from the siding shelf.

  • Page 9: Connections

    User's Manual 2.3 CONNECTIONS In the All Weather, Inc. AWOS 3000 system, the 1793 VHF radio is installed at the Central Data Platform (CDP). The VHF control cable connects the VHF radio to the AWOS Peripheral Interface PCB at terminal block J2 and the AWOS computer power supply. The cable is fitted with a DB9 connector at one end for connection to the VHF radio.
  • Page 10 1793 VHF Radio User's Manual Figure 7. VHF Radio Connections Figure 8. Connector Pinout...

  • Page 11: Calibration

    User's Manual 2.4 CALIBRATION The Model 1793 VHF Radio is calibrated at the factory prior to shipment, and should not need to be calibrated again during installation. Power level and modulation calibration are performed as part of the annual revalidation described in the Annual Revalidation Section.

  • Page 12: Operation

    1793 VHF Radio User's Manual 3. OPERATION A view of the front and transmitter indicators is given in Figure 9. A functional description of the power switch, controls, and indicators is provided in Table 1. 3.1 OPERATING VHF RADIO INSTRUCTIONS 1.
  • Page 13 1793 VHF Radio User's Manual Figure 9. Transmitter Controls and Indicators...
  • Page 14 1793 VHF Radio User's Manual Table 1. Operator's Switches, Controls and Indicators SWITCHES CONTROLS & FUNCTIONAL DESCRIPTION INDICATORS The toggle switch applies the DC power to the transmitter. The transmitter is ON/OFF switched to ON in the toggle LEFT position the transmitter is switched OFF in the SWITCH toggle RIGHT position.

  • Page 15: Maintenance

    If the problem persists, contact All Weather, Inc. Customer Service. 4.1 PERIODIC MAINTENANCE Periodic maintenance of the Model 1793 VHF Radio is divided into three categories within the maintenance cycle: monthly, triannual, and annual maintenance procedures. 4.1.1 Monthly Maintenance Check the cabling for integrity.
  • Page 16 1793 VHF Radio User's Manual 4.1.3.1 Power Level (At Transmitter) 1. Remove power from the VHF radio by turning the power switch on the radio front panel off. 2. Disconnect the VHF antenna cable from the BNC connector on the back panel of the CDP.
  • Page 17 1793 VHF Radio User's Manual 4.1.3.2 VSWR (At Transmitter) If the RF cables must be disconnected when switching between power level and VSWR tests, turn the radio off using the switch on the radio’s front panel. 1. Remove power from the VHF radio by turning the power switch on the radio front panel off.
  • Page 18 1793 VHF Radio User's Manual 8. Calculate the VSWR and enter the value on the Annual Technical Performance Record. If you measure forward and reflected power, calculate the VSWR using the following equation. reflectedpower 1  forwardpower VSW R reflectedpower 1 ...
  • Page 19 1793 VHF Radio User's Manual 4.1.3.3 Frequency If RF cables must be disconnected when switching between frequency and modulation tests, turn the radio off using the switch on the radio’s front panel. 1. Log the assigned frequency on the Annual Technical Performance Record.
  • Page 20 1793 VHF Radio User's Manual 4.1.3.4 Modulation If RF cables must be disconnected when switching between frequency and modulation tests, turn the radio off using the switch on the radio’s front panel. 1. Remove power from the VHF radio by turning the power switch on the radio front panel off.
  • Page 21 1793 VHF Radio User's Manual Figure 13. Tone Test Panel - AWOS 3000 9. Use the modulation adjustment potentiometer on the VHF radio to adjust the modulation depth to 90%, see Figure 3. 10. Use the VHF adjustment potentiometer (R29) on the CDP peripheral interface board to lower the signal level until the modulation decreases to 80%.

  • Page 22: Voice Output Static Reduction

    23. Remove the CD Key from the CDP optical drive. 4.1.3.5 Voice Output Static Reduction The Model 1793 VHF Radio has been adjusted for use with the AWOS 3000 to minimize audible static on the voice transmission. The following steps described how to reduce static should additional adjustment be required.
  • Page 23 1793 VHF Radio User's Manual 4.1.3.6 Transmission Line Loss 1. Remove power from the VHF radio by turning the power switch on the radio front panel off. 2. Disconnect the VHF antenna cable from the BNC connector on the back panel of the CDP.

  • Page 24: Specifications

    1793 VHF Radio User's Manual 5. SPECIFICATIONS Parameter Specification Frequency Range 118.000 to 136.975 MHz Channel Spacing 25 kHz Duty Cycle 100% Transmitter Power Output Adjustable (1 to 3 W) Output Power Stability VSWR Carrier Stability (-40 to +55ºC) ±1.000 Hz max Audio Input 0.5 V...

  • Page 25: Forms

    1793 VHF Radio User's Manual 6. FORMS These master forms should be copied and sufficient copies stored at a convenient location in each site's Facility Reference Data File (FRDF). The Annual Technical Performance Record is to be completed at system commissioning, after major repair work, and during annual revalidation.
  • Page 26 1793 VHF Radio User's Manual Annual Maintenance Data Sheet Measured Value Standard Value Acceptable Parameter Tolerance (A-B) Radio Power 2.5 W ±1.0 W (At Xmtr) Reflected Power VSWR 1.0:1 3.0:1 Frequency ±1.0 kHz Modulation 65-95% Transmission Line Loss 2.2 dB/50 ft. max.

  • Page 27: Warranty

    User's Manual 7. WARRANTY Unless specified otherwise, All Weather Inc. (the Company) warrants its products to be free from defects in material and workmanship under normal use and service for one year from date of shipment, subject to the following conditions:...
  • Page 28 All Weather Inc. 1165 National Drive Sacramento, CA 95818 1793-001 Fax: 916.928.1165 Revision A Phone: 916.928.1000 September, 2016 Toll Free: 800.824.5873...

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