An embodiment of a system for determining a distance and magnitude to one or more unknown passive intermodulation (PIM) sources associated with a network under test comprises a scalar PIM measuring instrument and a reference PIM source. The scalar PIM measuring instrument has an output frequency that is systematically changeable to produce a series of response signals of varying frequency and the reference PIM source is configured to introduce a reflected signal to the scalar PIM measuring instrument in response to the output frequency. The scalar PIM measuring instrument can perform data processing algorithms allowing the extraction of distance and magnitude information about the unknown PIM sources located along the network under test from scalar data received by the scalar PIM measuring instrument. The scalar data received by the scalar PIM measuring instrument represents a combination of signals from the unknown PIM sources and the reference PIM source.