"Hi Jon, On EBay, I recently won a one of a kind item, an outboard FM Quad demodulator adapter, the unit that all the quad receivers have the FM Multiplex output jack for. As you know having been around in the era, the endless news that any day now the FCC will approve FM Quad and that will make quad mainstream never happened. I was aware that various manufacturers who supported CD-4 made modifications to their receivers for testing the FM Quad system, so that in demonstrations they could receive test broadcasts in quad. JVC, Technics, even Sansui made a few QRX-9001 and 999s with built in quad FM demodulators, but I never saw or heard of outboard ones being made. This unit has a sticker on the bottom, "connect to RE-8420" which if you Google that model number you'll find it was an all in one quad receiver, probably came with 4 fairly cheap speakers, and had a built in Q8 deck. I'm assuming they (Panasonic) loaned the entire setup to people in the FM Quad test area, to receive and evaluate the broadcasts. Guess the guy who got this one never returned it to them after the tests were over. It powers up and works perfectly, as far as I can test without any Dorren FM Quad signal to receive. When connected to a quad receiver (QRX-7001) FM MPX out jack, and the signal fed back in via the tape monitor loop, you use the Sansui tuner but this demodulator is actually doing all the work beyond basic tuning to the station. This demodulator is receiving the raw FM signal, then decoding it to regular FM stereo since there is no quad to receive. It plays double stereo that way, same front and back, like most CD-4 demodulators do when playing a stereo LP. With a mono FM station it's 4 channel mono, all outputs are on. It has interstation muting, and when it comes out of muting as you first tune to a FM Stereo station, it assumes it to be Quad, so the FM 4-Channel indicator lights up in green and all 4 corner red lights light, then it analyzes the signal and finds no quad carrier, so it switches to double stereo and the FM Quad light goes out, and the rear red lights go out also. Sounds identical to the 7001's internal FM stereo, by switching between tape 1 and FM I could A-B it, no difference in sound or performance to my ear between the Panasonic Quad FM demodulator receiving the FM and Sansui doing it all in the receiver. So, I guess bottom line is that the system worked and had the FCC done something it really would have been what was needed to get quad moving, since then the FM broadcasters would have been the source for quad, and not no logic or pump-a-matic Sony SQD-2020 SQ decoders. The stations could have played open reels, or at least if playing records had state of the art decoders and demodulators rather than some of the junk that was sold for consumers. Obviously in the car it would have been great also, to have had a FM quad source easily available rather than Q8's." - Quad First