Chapter 9 Radio Maintenance MComm – Ch9 - 1

Confidence Testing Preventive Maintenance Corrective Maintenance Summary Overview MComm – Ch9 - 2 >>

On Air Testing Backup Systems Coax Adapter Confidence Testing MComm – Ch9 - 3 >>

Receivers  Listen on a hailing or working frequency  checks receiver and antenna Transmitter  Make test call on a working frequency  checks transmitter, receiver and antenna HF or satellite  Send message to self  checks your equipment and shore interface DSC radios  Make test call using DSC to another DSC radio  need to know their MMSI On-Air Testing MComm – Ch9 - 4 >>

Backup Systems If radio is inoperative, use handheld radio  Charge handheld radio every 3 months  Periodically test handheld radio Backup or Emergency VHF Antenna  If you suspect a bad antenna:  Use backup antenna  Isolates problem MComm – Ch9 - 5 >>

Coax Adapter With coax TNC to SO-239 adapter  Can use high fixed antenna with handheld  Good for when radio fails, but not antenna MComm – Ch9 - 6 >>

Cleaning Cables and Connections Batteries Corrosion Control Preventive Maintenance MComm – Ch9 - 7 >>

Cleaning Use fresh water and damp cloth  May add soap to water  Then wring out cloth Do NOT spray water on:  Coax fittings  Cable connections  Speakers  Microphones MComm – Ch9 - 8 >>

Once a quarter  Inspect power cables and antenna coax for:  cuts in outer cover  flattened coax (should be round)  sharp bends (coax should have 2 inch radius)  Tighten connections Once a year  Check connections inside power panel  CAUTION – first turn battery main switch “Off” Cables and Connections MComm – Ch9 - 9 >>

Cables & Connections - 2 Sailboats, every 5 years  Check antenna and coax at top of mast  spray connector with QD Electronic Cleaner  put dielectric silicone compound inside of connector  tape coax and connector with rubber mastic tape Powerboats, check every other year Every 10 years  Replace coax MComm – Ch >>

Batteries Every 3 months  Recharge handheld batteries Once a year  Replace all “flashlight” batteries  Check dated batteries (EPIRB and SART)  Have them replaced before expiration date may have to send unit to approved facility Lithium batteries are difficult to ship MComm – Ch >>

Corrosion Control Once a year, check  Power cables  Coax connectors  Microphone connections  Battery terminals If corrosion is noticed or suspected  Spray contacts inside of connectors with QD Electronic Cleaner  Then reconnect and tighten MComm – Ch >>

When an FCC License is Required Visual Checks DC Troubleshooting Coax and Connectors Other Corrective Maintenance MComm – Ch >>

For transmitter adjustments or repairs  Includes screwdriver adjustments  PG for radios  General Radiotelephone Operator license  Radar endorsement and PG for radars No license required  To install unit, antenna and cables  To repair/replace cables and coax When FCC License Required MComm – Ch >>

Visual Checks Circuit breaker and radio “ON”? Are controls (especially squelch) set correctly? Power cable properly connected? Blown fuse?  On back of unit  In hot wire near unit  In wire near breaker Microphone connected? Coax properly connected? Antenna damaged? MComm – Ch >>

DC Troubleshooting If radio is “dead” and fuse on radio is good Check power cable connection for corrosion  Spray with QD Electronic Cleaner  Reconnect power cable and test If radio is still “dead”  Disconnect power cable & measure DC voltage  Should be slightly over 12 VDC  Defective radio if <12 VDC MComm – Ch >>

DC Troubleshooting - 2 If no DC voltage at the end of power cable Check for blown fuse Check for loose wires inside power panel  At circuit breaker  At DC bus bar If wire connections good & have 12 VDC at CB  Defective wiring power panel to radio MComm – Ch >>

Coax and Connectors Check coax cable connector for corrosion  Use electronic cleaner  Reconnect and tighten Check antenna coax for damage  Flattened? (should be round)  Sharp bends? (should be 2” radius)  Replace if damaged Waterproof coax connections  Inside apply dielectric silicone compound  Tape outside with rubber mastic tape MComm – Ch >>

SWR Meter Used to test coax and antenna Place in series with antenna coax Voltage Standing Wave Ratio (VSWR)  Checks for impedance mismatches  Indicates defective coax, connectors, or antenna Output power  Verifies output power of transmitter  Can be used to measure attenuation in coax MComm – Ch >>

VSWR Measurement Insert SWR meter in series with antenna coax  Use short section of coax On an idle channel:  SWR meter switch to FWD  Key transmitter  Adjust sensitivity to full scale reading  Release PTT switch  Set switch on SWR meter to REF  Key transmitter  Read VSWR  Should be less than 2:1  3:1 indicates defective system MComm – Ch >>

Power Measurement Insert SWR meter in series with antenna coax  First next to transmitter, then next to antenna On an idle channel:  SWR meter switch to FWD  Adjust sensitivity to full scale reading  Set switch on SWR meter to POWER  Read output power  At transmitter should be 25 watts  Next to antenna should be approx 20 watts  If over 3 dB loss between transmitter & antenna Either coax or RF connectors are defective MComm – Ch >>

Defective Microphone? Press PTT switch, but TX does not work  Receiver stays on  May be defective mike or connection  Transmitter “keys” but no modulation  May be defective mike or connection Spray connectors w/ QD Electronic Cleaner  Then reconnect microphone If it still does not work  Try with known good mike  If radio now works, mike was bad MComm – Ch >>

Defective NMEA 0183 cable? Easy test  Good if DSC radio is displaying GPS info If no GPS data displayed and GPS is working  Probably have bad NMEA 0183 cable / wires Troubleshoot cable/wires like power cable  Check for corrosion  Use Electronics Cleaner  Check for loose wire connection  Tighten screw  Check each wire for continuity MComm – Ch >>

90% of problems are:  No DC to radio  Corroded connectors Visual checks will identify some problems Use a multimeter for voltage check  No DC: check breakers/fuses/wiring Make sure batteries are charged on backup Preventative maintenance is good Test before you need it Summary MComm – Ch >>