When equipped with Option 15, the Vector Voltmeter is a convenient tool for ensuring phase match between RF cables, especially in the field where access to AC power is typically limited. This mode is called Vector Voltmeter (VVM) because it can replace a classic vector voltmeter, which is becoming obsolete. The classic analog VVM had 2 input channels (typically A and B), and both were capable of measuring voltage directly. The classic VVM, however, did not have any internal signal source or bridges or couplers needed to perform reflection or transmission measurements. Those items needed to be supplied externally. With the proper addition and usage of those external items, the classic analog VVM could be configured to perform complex measurements (reflection or transmission) between the 2 inputs (A/B or B/A). Typically one of the input channels would be dedicated as the reference channel, and the remaining channel would be used to perform the desired measurements.

The A/B and B/A ratio measurements were the predominant usage of the classic analog VVM. The MS2085A/89A Site Master VVM provides equivalent A/B and B/A ratio capability, which means that it can be used as a drop-in replacement for a classic analog VVM. Since it already has a source and couplers built-in, it can also measure reflection or transmission of a DUT directly without needing any additional external items.

The Site Master VVM supports Single and Table display views. Table view provides convenient measurement of up to 100 devices + 1 reference simultaneously. May be used as a drop-in replacement for traditional Vector Voltmeters when A/B or B/A functionality is required.