My post to FB Aug 14
Does anyone know about the timelines on what I’m talking about below?
The early TRs (transistor radios) were AM only because the germanium transistors available were not capable of FM frequencies. The first TR was the Regency, and it used the Texas Instruments transistors that were similar to the Raytheon CK722. I’m guessing this was ’54.
The early germanium transistors had enough collector to base capacitance to make it necessary to use neutralization in the IF amplifier(s) to prevent oscillation and get enough gain. Not sure when, but the transistors (Ge or Si??) became lower capacitance and didn’t need to have so much neutralization, so they could be more easily assembled.
The cheap epoxy silicon transistors replaced germanium, and they could work adequately on the FM BCB, so AM/FM radios finally hit the market. National Semi and Fairchild Semi were leaders in low price ‘jelly bean’ transistors in the 1960s, but I’m not sure exactly when.
Sometime after that, maybe the ’70s, the SAW filters replaced IF transformers so the IFs didn’t require tuning, thus saving on assembly costs. The radios still required some alignment in the front end.
Eventually the radios became more integrated, more functions were done by a single chip. I don’t remember what year I started seeing chips in radios. I think the IF was changed to where it and the detector were using modern technology, like synch detection. Tuning became digital so only a few buttons were needed.
