Which method can be used to monitor the signal output during an ELT test?

Tuning a communication receiver to 121.5 MHz is the correct method to monitor the signal output during an emergency locator transmitter (ELT) test because 121.5 MHz is the emergency frequency designated for ELTs. When an ELT is activated or tested, it transmits a signal on this frequency, which can be detected by standard communication receivers designed to operate in this range. This allows for real-time monitoring of the signal’s output to ensure the ELT is functioning properly and broadcasting as intended.

Other methods may not provide the same level of reliability or direct confirmation of the ELT's signal output. For instance, using a frequency analyzer would typically require more specialized equipment and may not be as straightforward for common users performing an ELT test. Measuring voltage output does not directly indicate whether the ELT is transmitting at the required frequency; it's primarily a measure of power supply rather than signal performance. Reading maintenance logs provides historical data but does not offer immediate verification of signal transmission during a test.