What is considered the most accurate method of zeroing a synchro?

When zeroing a synchro, the most accurate method often involves using a high-precision instrument that can detect small changes in voltage. The AC voltmeter is specifically designed to measure alternating current voltage, which is the type of signal generated by synchros. Using an AC voltmeter ensures that any changes in the synchro's output are accurately measured because this instrument can more effectively capture the characteristics of the AC signal than some other meter types.

The precision of an AC voltmeter allows for fine adjustments when aligning or calibrating the synchro, ensuring that it performs correctly within the specified parameters. This level of accuracy is essential in applications where precision is crucial, such as in navigational or mechanical systems where synchros are commonly used.

While other instruments like a digital multimeter or galvanometer can also be used in measuring voltage, they may not provide the same level of accuracy and sensitivity for AC signals as an AC voltmeter. Therefore, the AC voltmeter stands out as the preferred choice when aiming for precision in zeroing a synchro.