[klondike98]

I don't see it in Rider Vol 1-23, nor in Beitman. Seems it may be a tough schematic to find; the Radiomuseum is looking for one: http://www.radiomuseum.org/r/kent_422.html

This fellow has one, you might try emailing him: http://web.eecs.umich.edu/~srs/Antiques/