Subelement B: MF-HF-DSC-SITOR (NBDP) Equip. & Operations— Topic :
Question 17B6
Element 9 (GMDSS Maintainer)Which would indicate proper operation of a SSB transmitter rated at 60 Watt PEP output in J3E mode?
Explanation
Proper operation of an SSB (J3E) transmitter relies on carrier suppression. In SSB, the carrier wave is significantly reduced or eliminated, and only the intelligence (audio signal) is transmitted as a single sideband. Consequently, power is only transmitted when there is an audio input.
Therefore, with the transmitter keyed but no sound entering the microphone, an ideally operating SSB transmitter should show no power output, as there is no audio information to modulate. This indicates effective carrier suppression, which is fundamental to SSB.
* **A) Incorrect:** SITOR is a digital mode, and its power characteristics differ from voice SSB. The question specifically asks about J3E (voice SSB).
* **C) Incorrect:** Fluctuating *well above* the 60 Watt PEP rating indicates overdriving the transmitter, leading to distortion and potential "splatter" (unwanted emissions). The PEP rating is the maximum allowable power.
* **D) Incorrect:** A steady indication suggests a constant carrier, which is characteristic of modes like AM or FM, or a fault in an SSB transmitter. SSB power should always fluctuate with speech.
Related Questions
17B4 An MF-HF transceiver is functioning correctly in voice mode/SSB but not in SITOR (NBDP). What is the most likely source of the problem?17B5 Which of the following conditions would be a symptom of malfunction in a 2182 kHz SSB radiotelephone?18B1 Which of the following conditions indicate the proper operation of a 150 Watt MF/HF transmitter in the F1B ARQ mode?18B2 Which of the following conditions indicate the proper operation of a 250 Watt MF/HF transmitter in the F1B FEC mode?18B3 Which of the following conditions could cause very low RF output in a MF/HF transmitter operating in the F1B FEC mode?