7.3 Equipment Faults (Key Topic 18)

7.3 Equipment Faults

When marine radio fails, the operator's first job is to stop making the problem worse, then to recognize which meter reading is actually a fault, then to improvise within the rules, and then to tell the master and the log. Key Topic 18 is that fault card: dirty transmitters, SITOR wattmeter behavior on a 60-watt PEP set, a 24 VDC GMDSS voltage that is too high, a dead antenna tuner, and the 2182 kHz symptom that must go to the master. OpenExamPrep provides this independent fault chapter for Marine Radio Operator Permit study. It is not an FCC maintenance manual and it does not claim official approval.

You are not being asked to redesign a tuner or to troubleshoot a switch-mode charger to component level. You are being asked to make the operating decision a licensed operator must make in the first minute: keep radiating, or not; treat the meter as normal, or not; bypass, or declare HF dead; call the master, or ignore a noisy daytime band.

Off frequency, overmodulating, or distorting: stop transmitting

Under normal circumstances, if the transmitter aboard your ship is operating off frequency, overmodulating, or distorting, you stop transmitting. You do not reduce to low power and continue. You do not merely turn down the audio volume and keep talking. You do not finish the gossip and then write a log entry while the dirty signal stays on the air. Logging may still be required, but logging is not a substitute for taking a defective transmitter off the air.

Off frequency means other stations cannot find you on the assigned channel, and you may be sitting on someone else's assignment — including a distress watch. Overmodulating splashes into adjacent channels and makes your own speech unreadable. Distorting is the audible result: broken, raspy, or unintelligible voice. All three are reasons to unkey, not to bargain with the wattmeter.

A related pool fact uses almost the same command in different words: if a ship radio transmitter signal becomes distorted, cease operations. Do not keep operating at reduced transmitter power. Do not keep operating with minimum modulation as a workaround. Do not keep operating after you have reduced audio amplitude. Cease. The two facts travel together: dirty RF is not a continue-at-low-power situation.

Proper 60 W PEP SSB: SITOR fluctuating 0 to 60 W

A transmitter rated at 60 watts PEP (peak envelope power) is the familiar compulsory MF minimum from the equipment-requirements topic. On SSB voice (J3E), PEP appears on speech peaks. A suppressed-carrier J3E transmitter that is keyed without speaking should show little or no output — a steady power reading with the mic keyed and silent is a warning, not a comfort. Speaking into the microphone should make the meter dance with the voice, not sit glued at 60 watts as if a carrier were present. A steady RF indication with no fluctuation while you talk is likewise the wrong picture for J3E.

The proper-operation picture this topic wants is SITOR (NBDP/ARQ) on that same 60-watt PEP transmitter: the power meter can be seen fluctuating regularly from zero to the 60-watt relative output reading. ARQ works in bursts. The ship sends a block at full PEP, then stops and waits for an acknowledgment, then sends the next block. The meter therefore climbs toward 60 W, falls toward zero, and repeats. That regular 0-to-60 swing is evidence the ARQ transmitter is peaking to its rated PEP and resting between blocks. It is not a broken power supply.

Do not confuse that SITOR swing with a voice-mode fault. If J3E voice shows a solid 60 W with no speech, look for carrier leak or a wrong emission. If SITOR shows a dead-flat zero while ARQ is supposed to be transmitting, that is a different problem — no output — which belongs with the 2182 kHz reporting rule below when it happens on the distress voice path.

24 VDC GMDSS: a constant 30-volt reading is a malfunction

A GMDSS station on a 24 VDC battery system should live near 24 volts at rest and a little higher when the charger is healthy — often the mid-20s. A constant 30-volt reading on the GMDSS console voltmeter is the malfunction example. Thirty volts sitting there without coming down is overvoltage: a charger or regulator problem, a wrong supply, or a metering fault that you must not treat as a fully charged 24-volt bank.

Contrast that with healthy charging behavior after you have tested the station on battery power:

• An ammeter that shows a high rate of charge that then declines is the bank taking current and then tapering. That is expected after a battery-power test, not the malfunction example.
• A voltmeter that reads 30 volts for a brief period and then settles to a steady 26-volt reading is a short charge peak followed by a normal charged voltage. That is not the constant-30-volt fault.

Daytime atmospheric noise on 2182 kHz is not a 24-volt malfunction either. The voltage item is about the console voltmeter on the DC bus, not about band noise.

Dead antenna tuner: bypass and about 30 feet of whip or wire

If the antenna tuner becomes totally inoperative, you can still obtain operation on both the 8 MHz and 22 MHz bands by bypassing the antenna tuner and using a straight whip or wire antenna approximately 30 feet long. Transmission is not impossible. You do not need a working tuner to touch two different HF bands if you choose a compromise length that can radiate on both. Shortening the whip to 15 feet is the wrong improvisation for this pair of bands.

A tuner changes the electrical characteristics of the antenna so the transmitter sees an acceptable match at the frequency in use. Bypass means the transmitter looks at the whip or wire directly. A wire about 30 feet long is close to a quarter-wavelength at 8 MHz (a quarter-wave in feet is about 234 divided by frequency in megahertz, which is about 29 feet at 8 MHz). The same 30-foot radiator is longer than a quarter-wave at 22 MHz but still radiates. A 15-foot whip is much too short for a useful 8 MHz quarter-wave and is the distractor length, not the workaround that covers both 8 MHz and 22 MHz.

This is an emergency operating improvisation, not a claim that a random wire is as efficient as a tuned antenna. Use lowest power necessary, watch the transmitter for high SWR or overheating if the console provides those indications, and restore the tuner as soon as you can. Do not leave a dead tuner in the line and hope F3E will fix an HF match — F3E is not the MF-HF voice emission, and a failed tuner still sits in the RF path if you do not bypass it.

No power on 2182 kHz when speaking: master and log

Which condition is a symptom of malfunction in a 2182 kHz radiotelephone system that must be reported to the master and then logged? No indication of power output when speaking into the microphone. You are on the MF distress and calling voice frequency, you are modulating, and the RF meter does not show output. That is a failed distress-voice path. The master needs to know the ship cannot transmit on 2182 kHz. The log needs the entry because it is a required-equipment failure, not a curiosity.

What does not meet that reporting example:

• A much higher noise level during daytime operation. Daytime D-layer absorption and atmospheric noise on MF are ordinary propagation, not a console fault by themselves.
• Failure to contact a shore station 600 nautical miles distant during daytime. Daytime MF ranges are often far shorter than that; skip and absorption explain many missed contacts without proving the transmitter is dead.
• An improper alarm-generator test into an artificial antenna that unmutes the distress-frequency watch receiver. That is a procedure error, not the power-output-when-speaking symptom.

Report and log the dead-mic-power symptom even if VHF Channel 16 still works. The master is entitled to know which distress system is down. Combine this with the stop-transmitting rule: if you do have output but it is distorted or off frequency, you still cease radiating; you do not keep a dirty 2182 kHz signal on the air while you walk to the bridge.

Worked fault scenarios

Scenario A. The 8 MHz public-coast pair sounds like you are off the published frequency and the other operator says you are splatter. Unkey. Stop transmitting. Do not drop to low power and finish the booking call.

Scenario B. SITOR ARQ to a coast station shows the wattmeter rocking from 0 to 60 W in a regular cadence on a 60 W PEP set. Treat that as proper PEP bursting, not as an unstable supply, unless other alarms disagree.

Scenario C. GMDSS console voltmeter has sat on 30 V all watch on a 24 VDC system. Treat it as a malfunction. Do not file it under fully charged. A tapering charge current after a battery test would have been the healthy picture.

Scenario D. The tuner motor is dead and you need both 8 MHz and 22 MHz. Bypass. Rig about 30 feet of whip or wire. Do not cut to 15 feet. Do not declare two-band HF impossible.

Scenario E. On 2182 kHz J3E, speaking produces no RF meter movement. Tell the master. Log it. That is the reportable 2182 kHz malfunction symptom, not high noon static.

Traps

• Continuing at low power, low audio, or low modulation instead of stopping a dirty transmitter.
• Reading a SITOR 0-to-60 W swing as a fault on a 60 W PEP set.
• Calling a brief 30 V charge peak or a tapering ammeter a 24 VDC malfunction, while ignoring a constant 30 V.
• Believing HF is impossible without a tuner, or bypassing with a 15-foot whip for 8 MHz and 22 MHz.
• Reporting daytime noise or a failed 600-mile daytime shot instead of no power when speaking on 2182 kHz.