What must be done when measuring port-to-port isolation between output ports of a splitter?

When measuring port-to-port isolation between output ports of a splitter, it is essential to terminate the common input port. Properly terminating the input port helps to ensure that the measurements taken reflect the actual isolation between the output ports without interference or reflections that might skew the results. This is because any open or unterminated port can create unwanted standing waves or reflections, leading to inaccurate readings.

Effective isolation testing requires a clear and defined response from the splitter, which can only be achieved by eliminating factors that could affect the measurements. By terminating the common input port, the test environment is standardized, allowing for a more accurate assessment of how effectively the splitter isolates one output from another.

In contrast, disabling all power sources does not directly contribute to measuring port-to-port isolation, as the process generally does not involve any powered components. Removing all other splitters from the network may not be necessary if they are not part of the measurement loop being tested. Similarly, using a frequency generator could be relevant in different testing scenarios, but it is not specifically required for the isolation measurement itself if the input is properly terminated.