This is the General History Section of
The Broadcast Archive
Barry Mishkind - The Eclectic Engineer
the Clear-Channel Matter
is the first in a series of 6 articles about the history of clear-channel AM radio stations.
The year was 1980. The FCC was about to dramatically alter the face of U.S.
broadcasting by issuing two rule makings. Docket 80-90 would soon transform the
FM band, but the issue with the longest history and heaviest baggage was the AM
This series of articles will describe how early radio regulations stimulated
the development of high-power AM broadcasting, by protecting the signals of
certain stations from interference across the United States. This protection was
designed to allow these high-power stations to deliver radio to under-served
rural areas. The mixed success of the plan and the opposition it generated from
the "have-not" broadcasters stimulated a 50-year regulatory brouhaha
that was finally settled by a 1980 Report and Order that would change the AM
The break up of the United States 1-A clear channels makes interesting
reading. The "clear channels" were the bedrock of what was called the
"Standard Broadcast Band." The stations given clear-channel protection
were incentivized by this protection to provide full-service programming across
their service areas, and they invested in the resources to carry out that
obligation. So it's not surprising that they were very concerned about
protecting and growing their investment. A look behind the curtain, where the
lobbying and maneuvering was going on, demonstrates the determination and
resolve of the players involved.
And what a conflict! On one side were the clear-channel broadcasters,
fighting to protect their wide service areas from encroachment by other signals.
To better serve those regions some were also pushing for AM "super
power", in the order of a half-million watts. On the other side of the
table were the rest of the broadcasters, the "have-nots" and others
who felt such a powerful concentration of media influence was not in the public
interest. What makes this story so remarkable is that many of the pivotal issues
in the battle would be irrelevant in today's radio world.
As far back as the late 1920s, industry regulators were concerned with providing
reliable nighttime radio to the under-served "white areas" of the
country. While a number of channels were set aside for wide-area coverage from a
single site, it turned out the stations on these "clear" channels
could not provide solid coverage of the vast under-served areas, even with
Given the physics of the situation, there seemed to be only two ways to solve
the problem: add additional stations on the clears, or grant massive power
increases to the existing solo operators. These alternatives would define the
clear channel issue for more than a half-century.
In researching this matter, we looked at thousands of pages of pleadings and
arguments, in public records and private libraries. We owe a debt of gratitude
to WCCO Radio for providing a review of its technical files, and we thank WSM in
Nashville for making available its own records and those of the Clear-Channel
Broadcasting Service (CCBS).
CCBS would play a key role in promoting the welfare of the clear channels and
advocating AM "super power."
In this regard we also want to recognize Ward Quall, one of radio's great
statesmen. He was a key force behind CCBS, and his input into this report was
invaluable. We also owe a "thank you" to Thomas White for his
excellent work on the formation of the broadcast band. Learn more at
What is a 'Clear'?
Section 73.231 of current FCC Rules defines a "clear channel" as
"one on which stations are assigned to serve wide areas." There was a
time when that was an understatement. Until the early 1960s, "clear
channel" meant just that: there was only one domestic assignment on each of
a couple of dozen AM frequencies from 640 to 1210 kHz. These solo signals were
not only protected within the United States but, because of the way
international radio agreements were written, neighboring countries had to limit
co-channel interference contours to no closer than several hundred miles from
their borders with the United States.
The current rules also specify that the "clear channels" will
provide wide-area service through a combination of daytime ground wave and
nighttime sky-wave energy. As we know, nighttime sky wave can extend the service
area of some AM stations far beyond the reach of tall-tower FMs. Sky-wave
coverage was one reason for the early success of full-service clear channel
stations, but it was this same sky wave that would become a major factor in the
ultimate reconfiguration of the AM broadcast band.
To better understand the fate of the clear channels, it's useful to review
how the initial "clear" assignments were made. In 1922 Secretary of
Commerce Herbert Hoover convened the first of four "Radio Conferences"
dealing with broadcasting in the United States. Out of that conference came the
first standard classifications of stations, by power and type of service. (Of
interest to our report was the so-called "Class B Radiotelephony
Broadcasting Station," the grandfather of the high-power clear-channel
Because so many early stations were clustered around three general frequencies -
"wavelengths" in the parlance of the day - it wasn't long before there
weren't enough "wavelengths" to handle the demand. So in 1923, Hoover
convened the Second Radio Conference, to deal with rising interference issues,
as more and more stations came on the air with little regard for precise
To satisfy the demand for licenses, the 1923 conference expanded the AM
broadcast band from 550 to 1350 "kilocycles" ("kc"), setting
aside channels from 550 kc to 1000 kc for "territorial" coverage, in
10 kc steps. (It would be more than a quarter-century before
"kilocycles" (kc) would become "kilohertz.") The 1923
conference also began to label operating channels by frequency rather than
wavelength. Forty of these frequencies (550-800 kc and 870-1000 kc) were
reserved for high-power wide-area "Class B" operation. (Shortly
thereafter, four more channels were added and the "B" group extended
to 1040 kc.) The country was divided into five radio zones, with the
"B" assignments spread more or less evenly across the five zones. The
conference thereby set the table for extensive protection of stations providing
high-power, wide-area service.
Déjà vu too
In 1924, the Third Conference extended the upper limit of the band to 1500 kc,
grouped the high-power Class B stations from 550 to 1070 kc and recognized
Canada's right to six of the channels. In the notes of the 1924 conference are
concerns about the efficacy of expanding the band to 1500, "since few
radios would tune that high." (This same concern would surface 60 years
later, during the Expanded-Band proceedings.)
As the spectrum filled, regulators searched for new ways to provide more
capacity. One group suggested narrowing the spacing to 8 kHz. Fortunately this
idea was put to sleep quickly. But this same sort of silliness would resurface
in the late 1970s when the NTIA, wishing to provide more channels "in the
name of opportunity and diversity," tried to convert the Western Hemisphere
to 9 kHz spacing.
While the broadcast industry was growing, radio receivers were undergoing
design improvements that made them far more sensitive. Better receivers pulled
in distant stations, which clashed with local signals. Listeners now heard
interference "whistles" of varying beat notes generated by frequency
drift in the equipment. (In broadcasting's infancy, the technical performance of
frequency-control equipment left a lot to be desired, and the beat would change
pitch, as tubes warmed up or as stations played with transmitter tuning).
In spite of the Radio Conferences, by the mid-1920s it was clear that radio's
expansion was outstripping the government's ability to regulate the industry.
Existing rules weren't adequate to govern operation on the crowded band. New
technical guidelines were being announced, but there was little enforcement. It
wasn't unusual for stations to change operating wavelengths and power levels
arbitrarily, to find the "clearest dial spot." (In the earliest days,
station frequency was set by aligning a knob pointer with a pencil mark on the
transmitter's "wavelength" control dial - a pencil mark left behind by
the last Radio Inspector.)
During what became known as the "Chaos of 1926," the Commerce
Department's authority was gutted by a federal district court, on a ruling
overriding Hoover's denial of a license to an unqualified applicant. Hoover and
Commerce threw up their collective hands and began to authorize everyone who
applied. Immediately some 200 new stations took to the air with abandon and with
little regard for the rules, and the result almost destroyed U.S. radio. It
quickly became obvious that, unless RF anarchy was to be the norm, a
"sheriff of the airwaves" was needed. A massive groundswell of
interference complaints finally stimulated Congress to enact the Radio Act of
1927, and to create the Federal Radio Commission to administer this new act.
The FRC's charter was two-fold: first, to establish "avenues through the
sky," radio channels freed of interference to the extent they could provide
reliable service over great distances; second, to "preclude obscenities
into the home", by enforcing rules of decorum on the licensees. Through a
set of "General Orders," the FRC confirmed 550 kc to 1500 kc as the
U.S. "Standard Broadcast Band." To provide "avenues through the
sky," they reaffirmed the set-aside of frequencies for wide-area coverage
and proposed that only one station be allowed to operate at night on each of
these 40 channels.
The "clear" channels and their occupants, as of October 1928, are
Many of these assignments would change over the next dozen years, and only KFI
and WMAQ would remain where they started with their original call letters. Of
interest to our story is that the Federal Radio Commission suggested the maximum
authorized power on these 40 channels might be "several hundred
kilowatts." This may have been the first official suggestion that
"super power" stations in excess of 50,000 watts might one day be
Certainly the signals being sent by the FRC gave hope to early investors that
their commitment to the growth of radio might be rewarded.
Moving ahead, we'll meet the "FCC" and watch as broadcasters built
toward 50,000 watts and beyond.
Copyright 2000 by
The 40 clear-channel assignments as of October 1928
Frequency (kHz)/ Dominant Station
1000 KYW (Chicago)
Source: The October 1928 "Radio Index" Tuning Book