Heathkit AJ-32

Found a filthy Heathkit AJ-32 tuner at a yard sale for twenty bucks. It was stored in a dusty garage for a long long time, but it cleaned up nicely.

Does anyone happen to have a operating manual and/or schematic? I would really appreciate a copy! Also, does anyone offer a re-cap kit?

Thanks for saving a great Heathkit tuner! No manual here, just glad to see a fine piece of history saved...

I have one and I traced out the schematic by hand, but I don't have a manual. Of interest is the 6C9 front end 10-pin miniature tube with the equivalent of two 6CY5 RF aligned-grid tetrodes inside. The FM demultiplexer is like the AC-11 external demux (a matrix design) but it adds a stereo indicator that AC-11 does not have. The AM has an RF stage and the FM has three IF stages. Both AM and FM have three tuning gangs.

This is a nice unit, although it does not have the sensitivity or RF noise performance of receivers with a cascode front end which was used on the Heathkit FM-3A but probably not on any other Heathkit tuner.

I like the uncluttered packaging, the style and the AM performance and the FM is good for most purposes but not the ultimate for RF or audio performance. Of course, every Heathkit is good for maintainability with bolted-in tube sockets rather than rivets and everything designed for ease of assembly.

I had one of these very tuners. If you don't know the history of this tuner, you will notice the mode selector says AM, FM and Stereo. Back in the old, early days of FM, they simply broadcasted the programs of the AM, as most stations back then could not afford to have separate broadcasts for their AM and FM stations. As a treat for evening entertainment, they would "simulcast", the AM station broadcasting the left channel and the FM station broadcasting the right channel. You would tune in each respective station of the that AM/FM station and then turn it to "stereo" to listen to the stereo broadcast. This was the time period when they had not figured out how to multiplex FM into a stereo broadcast.

You may know this, others may not......

Sort of accurate. It was done on an experimental basis for a while until the FCC finally decided between the four competing multiplex proposals. Simulcast stereo died very quickly after April 1961.

I wouldn't be surprised if this unit didn't have a multiplex decoder output. Most FM tuners I've seen from about 1959-1961 did.

Mine has a built-in stereo decoder based on the AC-11 but with an additional circuit for the stereo light (which the AC-11 does not have).