Subelement A: VHF-DSC Equipment & Operation— Topic :
Question 5A4
Element 9 (GMDSS Maintainer)What ohmmeter reading may indicate a faulty component in a VHF receiver?
Explanation
A transistor's emitter-base junction acts like a diode. A healthy diode exhibits low resistance when forward biased (current flows in one direction) and very high (ideally infinite) resistance when reverse biased (current is blocked). If an ohmmeter shows low resistance between the emitter and base in *both* directions (including when the test leads are reversed), it indicates that the junction is shorted or significantly leaky, which signifies a faulty transistor.
Conversely:
* **A)** Describes the expected behavior of a healthy diode, showing low resistance in one direction and high in the other.
* **B)** Zero ohms across an in-line fuse indicates it is intact and conducting, which is its normal, healthy state. A blown fuse would show infinite resistance.
* **C)** A healthy ceramic bypass capacitor blocks DC current. An ohmmeter, applying DC, should show infinite ohms (or a very high, rising resistance as it charges) across it, indicating it is not shorted.
Related Questions
5A2 Which of the following test procedures may be used to determine a VHF receiver’s minimum discernible signal?5A3 Which of the following procedures may be used in many U.S. ports as a quick field test to determine if a shipboard VHF receiver is operating properly?5A5 What condition may indicate a VHF receiver fault?5A6 What condition may cause noisy operation of a VHF receiver?6A1 What is the maximum allowable deviation of a marine VHF transmitter?