A master-oscillator power-amplifier transmitter has been operating normally. The antenna ammeter suddenly reads zero. What happened?

• A. A shorted antenna ammeter
• B. An open connection in the remote reading meter
• C. Both a and b
• D. None of the above

Answer: (C)

In the situation where a master-oscillator power-amplifier transmitter operates normally but the antenna ammeter suddenly reads zero, it indicates a potential problem in the circuit. A shorted antenna ammeter could lead to a reading of zero because it may create a path of least resistance that bypasses the measurement of current through the antenna.

Simultaneously, an open connection in the remote reading meter can also result in a zero reading because if there’s a break in the circuit, the meter will not receive the current flow necessary to display a reading. Thus, both scenarios described can independently lead to the observed zero reading on the antenna ammeter.

Therefore, the scenario reflects that either issue—either a short or an open circuit—is sufficient to explain the sudden drop to a zero reading, which makes the combination of both possibilities the correct answer.