The Kahn POWER-side Expander is a type of modulation technology which was developed by Kahn/Hazeltine Independent Side Band AM STEREO guru Leonard Kahn . Basically, it's purpose is to improve the transmission of signals by broadcasters and the subsequent reception of those signals by listeners. Here's how it works: a normal AM transmission has a carrier and two sidebands: a lower and an upper one; AM single sideband (SSB) transmission, on the other hand, has a carrier and only one sideband. The POWER-side is a cross breed of the two. Specifically, it provides a broadcaster with some of the advantages of SSB (i.e., less interference and greater range) with a compatible system for a normal AM receiver. As a result, an upgrade of equipment is not required by the AM listener. The POWER-side can also help in situations where one station is closer to another station on the AM dial and would like to minimize interference from the other. By putting most of the modulation of the station into the sideband that is furthest from the interfering station, the signal will (hopefully) arrive cleaner on the listener's AM receiver.
Recently, I was asked if I could address on The AM STEREO Page how Kahn POWER-side Expander technology works to de-null the nulls in an AM pattern and how it precludes a station from broadcasting in Motorola C-QUAM AM STEREO