Fisher FM-100 FM Tuner (1961)

Name: Fisher FM-100
Brand: Fisher

Five tubes, a slide-rule dial, and 1.8 microvolts of quieting - the plain FM-100 was Fisher's workhorse front end before the suffixes arrived.

Overview

The Fisher FM-100 is an FM-only tuner that arrived in 1961 at the front of Fisher's well-respected line of high-fidelity components. It is a tuner and nothing more. There is no amplification inside, and the fact sheet says so bluntly: power output is not applicable, because this box was built to feed a separate preamplifier and power amplifier. Buyers in 1961 understood the deal. You bought a tuner, a preamp, and an amp, and you put together a system rather than a console.

The headline number is sensitivity: 1.8 μV for 20 dB of quieting on FM. That is a serious figure for a 1961 tube tuner, and it explains why Fisher's advertising that year leaned hard on the "most sensitive FM tuner" claim. The company's copy from 1959 and again in 1963 pointed to professional users, including government agencies and university tracking projects, as evidence that these tuners met working standards rather than living-room standards. Audio (July 1959, p.39) ran Fisher's claim that the FM-100 was the tuner "used by radio stations" and by the Satellite Tracking Project of Ohio State University. That is advertising, not an independent verdict, but it shows who Fisher thought it was selling to.

The suffix question is what makes the FM-100 interesting today. The plain FM-100 sits at the head of a family that grew into the FM-100-A, FM-100-B, and FM-100-C, and collectors have spent years trying to pin down where the unsuffixed original ends and the B begins. The plain tuner shows up in Fisher's MPX-100 multiplex adapter instructions as a distinct entry alongside the FM-100-B-era models. That is one of the few pieces of period documentation that treats it as its own thing rather than a footnote to the later variants.

Key Features

1.8 μV Sensitivity Through Five Tubes

The RF and IF chain runs on five vacuum tubes - 6AQ8, 6U8, 6BA6, 6AL5, and 6AU6 - and the fact sheet credits that arrangement with the tuner's low-noise amplification and smooth signal handling. The 1.8 μV for 20 dB quieting rating is the number that matters. It means the FM-100 will pull usable signal out of a modest antenna, and owners have long reported that it captures weak stations with relative ease for its era. Five tubes is a lean complement for a serious tuner, which is part of why the FM-100 has a reputation for running cooler and quieter than some of the tube-heavy competition.

Slide-Rule Dial with Precision Tuning Knob and Analog Meter

Tuning is by slide-rule dial driven through a precision tuning knob, with an analog tuning meter for signal strength and center-of-channel alignment. There is Automatic Frequency Control on board. The AFC switch locks the tuner onto a station and fights the thermal drift that tube tuners of the period were prone to. Dial, meter, and AFC were what a 1961 FM listener expected: no presets, no digital readout, just a needle and a knob and five tubes warming up.

Stereo-Ready via External Multiplex Adapter

The FM-100 was designed to be stereo-ready, meaning it accepts a multiplex adapter, sold separately, to decode FM stereo broadcasts. The adapter is not built in. The fact sheet is explicit about that, and it is the most important thing to know when buying one today: a plain FM-100 on its own is a mono tuner until you add the MPX box. Fisher's MPX-100 instructions list the FM-100 alongside the FM-40, FM-50, FM-90(X), and FM-200 as tuners that connect to the adapter through their MAIN and REC outputs, with the MPX-100's stereo/mono automatic switch handling the decoding. Current listings frequently pair the tuner with an MPX 20 multiplex unit, which is the practical route most buyers take.

One owner on the Vintage Asylum forum in 2004 described the FM-100 as "a mono tuner with the option to convert to stero hence the MPX option on inside". That is an owner's guess about internal wiring, not a documented spec, and should be treated as such. The fact sheet's own description is narrower: stereo-ready via external multiplex adapter input.

Brushed Aluminum Front Panel, Black Cabinet

The FM-100 wears a brushed aluminum front panel over a black cabinet, the standard Fisher house look of the period. The fact sheet does not give dimensions or weight, so any claim about how much shelf space it takes is unverified.

Historical Context

The FM-100 landed in 1961, in the transitional period between vacuum tube dominance and the rise of solid-state electronics. FM broadcasting was gaining popularity in the early 1960s, high-fidelity home audio was becoming more accessible to middle-class consumers, and stereo FM broadcasting was beginning to roll out. Fisher built a series of high-performance tuners known for their sensitivity, selectivity, and build quality, and the FM-100 was one of them.

The plain FM-100 did not stay plain for long. Fisher went on to produce the FM-100-A, FM-100-B, and FM-100-C variants. The FM-100-B became the model most people mean when they say "FM-100" today. It is the one that appears in period advertising, and the one that shows up most often on the used market. The FM-100-C followed in the mid-1960s, still tube-based, still FM-only, and still aimed at the same listener. Solid-state would take over Fisher's line before the end of the decade, and the FM-100 family sits on the tube side of that line.

Collectibility & Value

The FM-100 carries a collectibility rating of 6/10 among vintage audio enthusiasts. It is not as rare as Fisher's later 500 or 800 series receivers, but it remains a respected representative of early 1960s tuner design, and collectors like its classic styling, functional design, and place in Fisher's engineering lineage. Market value sits at $100-$250 USD for the plain tuner. Unrestored working units typically sell at the lower end, and fully restored, properly aligned examples bring higher prices, especially with original documentation or accessories.

Recent listings show a wider spread. A working FM-100 paired with an MPX 20 multiplex adapter has been listed around $349, while FM-100-B examples have appeared at $249, $420, and $525 depending on restoration status. Three of those four listings are FM-100-Bs, not the plain FM-100, and the FM-100-B is a different variant. The FM-100-C variant has been listed on European sites with an estimated value around €375, but that figure applies to the C, not to the tuner on this page.

Maintenance is the usual tube-tuner story, and the fact sheet is specific about it. Aging capacitors are the most common cause of noise, hum, or failure. The standard advice is to replace all electrolytic and paper capacitors, especially the coupling and power supply caps, before putting the tuner into regular service. All five tubes should be tested for wear, with weak or noisy examples replaced by tested NOS or high-quality equivalents. Contact cleaner on the tuning knob shaft, input jacks, and selector switches clears up crackling and intermittent signal. Alignment should be done professionally with a signal generator and the proper service manual procedures, since misalignment measurably reduces sensitivity and stereo separation. Older power transformers can develop shorts or excessive hum, and the tuning meter should be checked for function and calibration. Restoration is strongly recommended before regular use, since decades of storage degrade components whether or not the unit was ever powered up.