SSB Adapter for Collins 75A-2 and 75A-3 Receivers - $81 - (Godfrey, ON)
These are great AM receivers, but were built before SSB came into general use. With this adapter, they become great SSB receivers as well. You plug the unit into the detector/AVC rectifier tube socket, remove some small components, make a couple of wiring changes, and connect two wires. The receiver operates exactly as before, except for the improvement in SSB reception. Operation in AM is unchanged. If an NBFM adapter is present, it continues to operate as before. When the BFO is turned on, a single-balanced product detector and dual-time-constant AVC system are switched in automatically. With the BFO off, a diode envelope detector and the original AVC circuit are switched in to provide AM operation. Some under-the-chassis work is required. We recommend that you go to Normal 0 Normal 0 http://www.treetopcircuits.com/docs/SB75Manual.pdf and download the owner's manual before buying. This is about a 1 megabyte file, so it may take a few minutes to come down on a slow Internet connection. We'll also be glad to respond to questions.
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From ebay.com - 1 month ago