Turns ON/OFF an auxiliary RF source. The auxiliary RF source takes
one port of the 4 port VNA to output the second RF source with
programmable frequency and power (4-port VNA only).
The second RF source can be used, for example, as a LO in mixer
measurements.
The auxiliary port can not be used for measurements. Ports are
divided into two groups: 1, 2 and 3, 4. The second port of the group
that comprises the auxiliary port can not be used as a stimulus.
(command/query)