Still looking.... I'm trying to use some Motorola Permacode filters (those used in Minitor II pagers) to make my own home-brew two-tone decoder. Does anyone happen to have the pinout for the Permacode filters? These are 4 pin devices and I suspect the pins are Ground, Power In, Audio In and Audio Out. I'm sort of groping in the dark a bit here. I'm also looking for the specific voltage used to power the filter. And finally, what's the expected output from the Permacode filter with the proper frequency input tone?: a sine wave at the desired frequency (like a very high Q band pass filter)? or is there a level detector in the Permacode filter so the output is a DC value (i.e, something like low output on correct tone detect and high output otherwise)? I've checked the obvious sources (google, repeaterbuilder.com, radioreference.com), but haven't found anything. I'm hoping that someone has an old Minitor II service manual in their files and could take a look at that and let me know. I appreciate any information people can provide about these filters. Thank you.