Pilotuner T601 FM Tuner (1947)

     

Introduced in 1947, the Pilotuner model T601 FM tuner helped to introduce a generation to the wonders of FM radio broadcasting.

FM vs. AM

FM radio was invented in the 1930s, but it didn't become popular until after World War II.

We are all familiar with the standard AM radio band, which reaches from 550-1600 kilohertz. Since the earliest days of radio, AM broadcasts have been plagued by static, whether from faraway thunderstorms or more local sources of interference. The technology also limits AM radio to relatively low-fidelity sound.

Edwin H. Armstrong, arguably the greatest innovator in radio history, created FM (frequency-modulated) broadcasting in 1933, as a static-free, high-fidelity alternative to AM (amplitude-modulated) broadcasting.

AM broadcasting uses a fixed frequency—for example, 710 on the radio dial—and varies the amplitude (strength) of the signal to send audio to your radio receiver. FM broadcasting turns that idea on its head. It uses a fixed amplitude and varies the frequency to send the audio.

This brilliant concept eliminates static from FM broadcasts and it also permits broadcasting of stereophonic sound, whereas AM is limited to monophonic sound.

Although his life was highlighted by technical triumphs, Armstrong was forced to spend decades defending his ideas in a swarm of lawsuits involving major radio corporations. He committed suicide in 1954. His widow eventually won a fortune in legal damages against the companies which contested his rights.

If you're interested in learning more about Edwin Armstrong and the development of FM and his other radio inventions, I recommend the book "Empire of the Air" by Thomas S.W. Lewis. You can find other technical and biographical materials through online searches.

Before World War II, FM broadcasting, like television broadcasting, remained somewhat experimental. Receivers were expensive and hard to find, and few if any broadcasting stations could be found outside a major city such as New York. Following the war, many new FM stations went on the air, and radio manufacturers leaped at the opportunity to exploit a growing new market.

In the immediate postwar years, when the Pilotuner was made, most people still owned prewar radios without FM capabilities. However, many of those radios had a connector in the back where you could plug in a phonograph turntable. Produced in this transitional phase, the Pilotuner was an ideal accessory, allowing you to transform your old AM-only radio into a new FM radio without any modifications.

As a historical footnote, if you buy a prewar radio with FM, it will not receive current FM broadcasts. After the war, the FM band was changed to different frequencies, making prewar FM sets obsolete. You can read more on that topic in my Philco 42-350 article.

Description

The model T601 Pilotuner is simply an FM radio without an audio amplifier or speaker. It is designed to connect to a stand-alone audio amplifier or plug into the audio section of an AM-only radio, just like a phono turntable.

Here is a front view of the Pilotuner. The controls are simple: an on/off switch and a tuning knob. We can see that it covers the modern FM band, 88-108 megahertz.

Housed in a compact wooden cabinet, the Pilotuner is convenient for setting atop any radio.

The tuner's backplate has detailed instructions for connecting it to a radio or amplifier.

With the back cover removed, we can see most of the tuner's five tubes, which are listed below.

Tube Type Function
V1 6BA6 RF amplifier
V2 6BE6 Converter
V3 6BA6 1st IF amplifier
V4 6BA6 2nd IF amplifier
V5 6AL5 Ratio detector

You can download the service manual, which includes connection instructions, from Nostalgia Air.

Final Thoughts

If you have never listened to a good FM tuner of this vintage, you may be pleasantly surprised by its sound quality. I enjoyed using mine in tandem with my Scott 210B monophonic amplifier.

FM accessory tuners of this type were manufactured for only a few years, during the time when FM was growing in popularity and many people still owned AM-only radios. By the mid-1950s, many radios included FM as well as AM reception.

The Pilotuner was one of the best-designed and most popular accessory tuners and it can still be found at a modest price. This one had been completely restored when I got it. After enjoying it for a couple of years, I gave it to a friend as a little surprise gift.

©1995-2017 Philip I. Nelson, all rights reserved