Fisher FM-80
A monophonic Fisher FM tuner from before the multiplex era. It can still be pushed into stereo with a soldering iron and a period adaptor.
Overview
The FM-80 belongs to the first generation of Fisher FM tuners, built before stereo multiplexing became standard equipment. The clearest sign of its age is what it lacks: a multiplex output jack. Fisher's own MPX-100 adaptor manual groups the FM-80 with the 50-R, the 70-RT, and early production runs of the 80-R and 80-T as units shipped without that connector. The same manual lays out the retrofit. Add a standard RETMA phono jack to the chassis near the 6AL5 tube socket, and wire it through a .01 mfd, 250V capacitor to Pin 1 of that tube. From there, a three-foot cable runs to the HIGH LEVEL jack on the MPX-100, and the tuner's main outputs feed the adaptor's left and right inputs. A careful owner could do it at the bench, and plenty evidently did.
That retrofit is the most documented thing about the FM-80. It says something about how Fisher positioned the tuner. FM stereo was arriving but not yet assumed, and the MPX-100 was the bridge. Fisher's instructions treat the FM-80 as one of a family of tuners that could be brought forward rather than replaced, which kept these units in service long after newer multiplex-equipped models appeared. As High-Fidelity (1956, p.142) noted in its test of a Fisher tuner of this era, the dial was well spread out and a logging scale was supplied as was Fisher's custom, with sound quality meeting the Fisher standard in every way.
The surviving documentation here doesn't say what the FM-80 sounded like, how sensitive it was, what it originally cost, or when it was built. The tuner does show up in period classified listings as used goods. One 1950s tape-recording magazine carries a seller asking $95 for an FM-80 described as being "as the day it left the factory," and another lists one at $98 alongside a Fisher 80AZ amplifier. Those are secondhand asking prices from the era, not retail, but they put the FM-80 in the same owner's rack as Fisher's 80-series amplification.
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