Recent Updates -
December 2011 - Updated Mouser parts list, and started new Yahoo discussion group, fm-mpx. For questions on the LM4500 board and associated circuits, building, adjusting, please visit this group - http://groups.yahoo.com/group/fm-mpx/
Welcome to the FM MPX site, which is dedicated to information on stereo MPX adapters. To start, it highlights the LM4500 stereo MPX adapter project. I started this project almost 10 years ago, while looking for a high performance stereo adapter for late 50ís mono FM tuners. I found a source for LM4500 chips, and since then Iíve built five LM4500 adapters. The first one was hand wired, and the rest were done with DIY printed circuit boards, using the toner transfer method. In learning to make make boards at home, I ended up etching 3 different versions of the board before I was happy. After getting it pretty well optimized, the board design was done double sided with silkscreen and mask at a PCB house, and now looks excellent. Thatís the version Iíll make available to anyone else that would like to build one. Hereís a picture of the the last homemade version, shown with an output filter designed by our our FMTuner contributor Ray.