A 1983 U. S. postage stamp depicting
Edwin H. Armstrong, an inventor of frequency modulation.
This page shows some of the events in the early history of FM
broadcasting in the United States. Note that apex stations referred
to on this page used amplitude modulation on VHF frequencies; many of
them evolved into FM stations. For dates involving the earliest
stations, see also the "earliest FM stations" page at this website.
Thanks to Bob Carpenter, Winston Tharp, Donna Halper, Steve Reggie,
and Robert W. Paine, who assisted with this page. The page is
maintained by Jeff Miller.
Suggestions are welcome.
Last revision: Nov. 23, 2015
1902. A patent application submitted by Cornelius Ehret of Philadelphia describes the use of frequency modulation in both radiotelegraphy and radiotelephony and includes circuitry for both FM transmission and reception, according to Gary Frost in Early FM Radio: Incremental Technology in Twentieth-Century America.
1921. The term wave-length modulation appears in Thermionic Tubes by J. Scott-Taggart.
Feb. 1922. A paper “Notes on the Theory of Modulation” by J. R. Carson appearing in the Proceedings of the Institute of Radio Engineers contains the earliest known use of the term frequency modulation:
It has been proposed..to employ an apparently radically different system of modulation which may be termed frequency modulation as distinguished from amplitude modulation, in the belief that the former system makes possible the transmission of signals by a narrower range of transmitted frequencies.
The paper shows that the bandwidth required for frequency modulation is at least twice the highest modulating frequency. The paper concludes that “this method of modulation inherently distorts without any compensating advantages whatsoever.”
Winter 1933-34. Armstrong demonstrates frequency modulation to executives and engineers of RCA.
Dec. 19, 1933. According to Famous First Facts:
1st FACSIMILE BROADCAST IN ULTRA-HIGH FREQUENCIES was made December 19, 1933, by station W9XAF, Milwaukee, Wis., on frequencies of 42,000-56,000 kilocycles and 60,000-86,000 kilocycles.The station was not using frequency modulation.
May 1934. Edwin Armstrong begins testing at the Empire State Building.
June 16, 1934. First test conducted of Armstrong's W2XF on 41 MHz from the Empire State Building, with RCA's cooperation. He transmitted using both amplitude modulation and frequency modulation.
April 1935. Armstrong receives a message from Sarnoff telling him to remove his FM equipment from the Empire State Building. [According to one source, testing continued there until October.]
Summer 1935. Armstrong rebuilds W2AG Yonkers (Carman R. Runyon Jr.) to operate on 110 MHz.
Nov. 5, 1935. Armstrong demonstrates reception of W2AG at a meeting of the Institute of Radio Engineers 17 miles from the station. The ID for the transmission was, “This is amateur station W2AG at Yonkers, New York, operating on frequency modulation at two and a half meters.”
May 1936. Armstrong's paper "A Method of Reducing Disturbances in Radio Signaling by a System of Frequency Modulation" appears in the Proceedings of the Institute of Radio Engineers.
June 1936. Armstrong describes his FM system at FCC hearings; critics predict the system is impractical.
July 1936. Armstrong granted experimental license for FM station.
Jan. 1, 1937. Broadcasting reports apex station W9XAZ Milwaukee (Milwaukee Journal) has become, as far as is known, the first apex station to originate its own programs on a regular schedule. Station operates on 26.4 MHz.
Mar. 2, 1937. The FCC authorizes two new apex stations, to WCHS Charleston WV, for the 26 MHz band, and to KGFJ Los Angeles, in the 88, 120, 240, and 500 MHz bands. These are the first apex authorizations since Jan. 21, 1936.
Mar. 9, 1937. The FCC authorizes an apex station to General Electric in Albany on 31.6 to 41.0 MHz.
Spring 1937. Shepard applies for a permit for a 50-kW FM station in Paxton.
Aug. 18, 1937. The FCC issues the first FM construction permit, to W1XOJ, the Yankee Network, Inc., Paxton, Mass.
Oct. 18, 1937. The FCC makes public its allocation plan for VHF: 75 channels with 40 kHz separation on 41.02 to 43.98 MHz for apex stations and 16 channels in 30-40 MHz for relay stations
Late 1938. W1XPW Meriden (WDRC, Inc.) is authorized experimental operation on 40.3 MHz. (In 1936, W1XSL Meriden CT had been licensed as an amplitude modulation apex station.)
Jan. 27, 1938. FCC announces its allocation of 25 channels with 40 kHz separation from 41.02 to 41.98 for use by educational stations. Stations are to use amplitude modulation unless a need for FM can be shown.
Jan. 15, 1938. Broadcasting reports Yankee Network starts construction of a 50 kw FM station atop Mt. Washington and that Armstrong is building a 50 kw FM station at Alpine NJ.
Apr. 10, 1938. Edwin H. Armstrong's W2XMN carrier is turned on for the first time, 43.7 MHz, 600 watts. For more information on W2XMN, see the E. H. Armstrong website.
Oct. 1938. Construction of W1XOJ begins.
Nov. 1938. WNYE New York goes on the air, using amplitude modulation.
Nov. 21, 1938. WBOE Cleveland is licensed for 500 watts on 41.5 MHz, using amplitude modulation. According to the 1961-62 Broadcasting Yearbook, the station went on the air in Oct. 1938.
Late 1938. W1XER moves its transmitter from Quincy to Mount Washington and begins operation on 42.3 MHz, using amplitude modulation.
Jan. 5, 1939. Apex station W8XNU Cincinnati (Crosley) begins a regular schedule of daily broadcasts, on 25.95 MHz with 1000 watts.
Jan. 11, 1939. FCC engineers listen to Armstrong's FM station from Sayville, New Jersey, 50 miles from the transmitter site. The station was operating on 42.8 MHz with 20 kw. They also listen to FM station W2AG Yonkers, operating on 110 MHz with 500 watts.
Feb. 1, 1939. Broadcasting reports General Electric engineers recently set up two experimental frequency modulation transmitters at Albany and Schenectady, operating on the same frequency. They drove a test car between the two cities and found almost no areas of interference between the stations. The stations were W2XDA Schenectady and W2XOY New Scotland.
Feb. 1, 1939. Broadcasting reports that the FCC feels that tests using frequency modulation should be expedited before apex broadcasters, using amplitude modulation, become entrenched. It reports about a dozen apex stations are licensed, and that several are receiving highly satisfactory results, notably WWJ, WKY, and WBEN.
Feb. 1, 1939. Broadcasting reports Professor Daniel Noble of Connecticut State College is experimenting with FM in the 100 MHz band.
Mar. 23, 1939. Armstrong demonstrates reception of his 20 kw FM transmitter at Alpine and a 600-watt transmitter at Yonkers to the Radio Club of America at Columbia University.
April 1939. Apex station W4XA Nashville begins a regular schedule of programs on 26.15 MHz.
May 13, 1939. W1XPW Meriden (WDRC, Inc.) begins on-air testing from its site atop Meriden Mountain. Station operates with 2 kw, awaiting higher power transmitter.
May 26, 1939. John Shepard in conjunction with the Institute of Radio Engineers demonstrates FM at Northeastern University for several hundred college professors, engineers, scientists, and technicians.
May 27, 1939. W1XOJ Paxton (Yankee Network) goes on the air on 43.0 MHz with 2000 watts. (To relay programming the Boston studios of the Yankee Network to Paxton, W1XOK on 133.03 MHz with 250 watts was used. Donna Halper reports this station appears to have become WEOD and then disappeared completely.)
June 1939. WTMJ applies for CP for experimental FM station
June 1, 1939. Broadcasting article lists stations using Armstrong modulation now in operation or under construction:
July 18, 1939. First day of regular programming for W2XMN Alpine (Armstrong), 42.8 MHz, 35,000 watts. The following is taken from Rebel In Radio by Elliott M. Sanger:
On July 18, 1939, Armstrong's transmitter carried the world's first regularly scheduled program on FM radio. The entire program originated from WQXR's studios in New York City. The telephone company had installed a special high-fidelity telephone line to carry the program from the WQXR studios to W2XMN in Alpine, New Jersey. (The first two selections were Tchaikovsky's "Haydn's Symphony No. 100" and "Francesca da Rimini.”) Not too many people could listen, however, for there were just 25 FM receivers in the world. But those who did listen agreed that a revolution in radio broadcasting had taken place.July 24, 1939. W1XOJ Paxton begins a regular schedule of 16 hours a day on the air, on 43.0 MHz. The station is still using 2000 watts but later will increase to 50 kw.
Aug 1, 1939. Broadcasting reports there are four groups of frequencies for FM:
Aug. 29, 1939. W1XSN Springfield begins some experimental broadcasts, according to notes from Gordon Swan [Donna Halper provided this information].
Sept. 1939. W3XO Washington is placed into operation, with 1000 watts on 43.2 MHz, according to Broadcasting of Nov. 1, 1939, which reports Jansky & Bailey "are experimenting with it regularly.”
Oct. 15, 1939. Broadcasting reports WOR was recently authorized an FM station on 43.3 MHz with 1000 watts, and that it will use the call W2XWI.
Oct. 15, 1939. The abbreviation "F-M" makes its (apparent) first appearance in Broadcasting magazine. Beginning with the March 15, 1940, issue, the abbreviation is changed to "FM.”
Nov. 1, 1939. Broadcasting reports, "The Commission on Oct. 24 also authorized W2XAG, F-M station at Yonkers, N. Y., operated by Carman R. Runyon Jr., pioneer experimenter with the system, to change to the high-frequency classification and to operate with 5,000 watts on 117.19 mc.”
Nov. 8, 1939. W2XQR New York (John V. L. Hogan) begins broadcasting, on 43.2. The following is taken from Rebel In Radio by Elliott M. Sanger:
The station had applied for an FCC license to broadcast in the then new high fidelity FM band, and went on the air in November 1939, with call sign W2XQR - the first FM station in the world (barring the experimental W2XMN of Armstrong). Major Armstrong lent the station his FM transmitter which was promptly installed at 42nd Street and Lexington Avenue, atop the 54 story Chanin Building. It stayed there until the station moved to the Empire State building in December 1965.
Nov. 11, 1939. The start date for W8XVB Rochester (Stromberg-Carlson Co.), according to the 1946 Broadcasting Yearbook.
Dec. 3, 1939. Experimental FM relay broadcast is successful: W2XCR Yonkers broadcast a special program which was picked up by W2XMN Alpine, which relayed it to W2XPW Meriden. It was then received at the WDRC studios.
Dec. 19, 1939. FCC press release addresses issue of commercial FM licensing
Jan. 1940. NBC begins regular FM transmission from Empire State Building on W2XDG, 42.6
Jan. 4 and 5, 1940. Experimental FM relay broadcasts: W2XCR Yonkers to W2XMN Alpine to W1XPW Meriden CT to Worcester to W1XOJ Paxton MA to W1XOY at Mt. Washington to Boston AM station.
Jan. 15, 1940. W9XAO Milwaukee (The Journal Co.) begins tests on 45.5, claiming to be the first FM west of Alleghenies and fifth FM in U. S.
Feb. 2, 1940. Start date for W9XEN Chicago (Zenith).
Feb. 1940. Start date for WXAD Rochester (WHEC, Inc.).
Feb. 5, 1940. Start date for W1XSO Hartford (Travelers Broadcasting Service Corp.).
Feb. 23, 1940. W9XAO Milwaukee begins a regular program schedule.
Feb. 28, 1940. W2XOR New York (Bamberger Broadcasting Service) starts regular broadcasting under a special temporary authorization
Mar. 3, 1940. New York Times reports that with the introduction this month of W2XOR, there are now three frequency modulation stations in the area: W2XOR, on 43.4, with programs of the Mutual Broadcasting System; W2XMN on 42.8, which is on the air Mondays through Fridays from 4 to 11 p.m., with programs of the Columbia Broadcasting System; and W2XQR on 43.4, which broadcasts daily from 5 to 10 p.m. [The article shows two stations on the same frequency; this may be an error.]
Mar. 15, 1940. Broadcasting lists the status of FM stations as of March 13.
(Bob Carpenter believes W3XMC never went on the air.)
Mar. 15, 1940. W9XYH Superior, Wis., begins daily broadcasting, the farthest west FM station.
Mar. 18, 1940. FCC FM hearings begin
Mar. 29, 1940. Start date for W8XVH Columbus (WBNS, Inc.) 43.0 MHz.
May 20, 1940. FCC authorizes commercial FM effective July 1, 1940, on 42-50 MHz. However, the authorization is later rescinded.
June 15, 1940. Broadcasting reports educational stations licensed to date for amplitude modulation are WBOE Cleveland and WNYE New York, and that WBKY Beattyville, Ky., has a construction permit. "It is presumed that these, along with all other future applicants, will change to FM.”
June 15, 1940. Broadcasting reports W2XWG is operating from 4 to 11 p.m. on Tuesdays through Saturdays on 42.6 MHz.
June 17, 1940. Start date for W1XTG Worcester (Telegram Publishing Co.).
Aug. 1, 1940. W2XOR (Bamberger Broadcasting Service) begins operation as New York's first fulltime FM station, operating 15 hours daily on 43.4 MHz with 1000 watts.
Aug. 4, 1940. New York Times reports on New York FM stations:
42.6 W2XWG operates Monday through Friday 3 p.m. to 11 p.m. experimentally
Aug. 15, 1940. The Board of Education of the San Francisco Unified School District is granted a CP for 1,000 watts on 42.1. The station will use frequency modulation.
Sept. 1940. W1XPW begins a regular program schedule
Sept. 1, 1940. Broadcasting reports educational station WBOE Cleveland has requested authority to relinquish its 41.5 MHz AM operation and change to FM operation on 42.5 MHz.
Sept. 4, 1940. Variety reports, "WDRC is divorcing itself from its offspring FM station, W1XPW, putting same officially on its own two feet Monday [as of September 16, 1940]. At that time, W1XPW will become a separate entity, broadcasting its own programming and maintaining its own staff. Believed to be the only FM in the country to maintain its own set-up, it will operate at the start on a 12-hour a day basis.” The article also said that W1XPW had been "in operation with 1000 watts power for about a year," and had applied to the FCC for a boost to 50,000 watts [Donna Halper].
Oct. 2, 1940. FCC adopts rules changes assigning frequencies with 200 kHz separation for FM broadcasting:
For rural areas: 43.1-44.3
[Some nice photos of FM radios which tuned to the 42-50 MHz band are
Oct. 17, 1940. WBKY Beattyville, Ky., goes on the air at 7:30 p.m. on 42.9 MHz with 100 watts [This station probably used amplitude modulation.]
Oct. 31, 1940. FCC grants 15 stations the first construction permits for commercial FM operation:
Nov. 20, 1940. W2XOY Schenectady (General Electric Co.) begins transmitting on a regular schedule, according to an article in FM in January 1941.
Dec. 6, 1940. W1XK licensed for experimental operation (information provided by Donna Halper, from Gordon Swan's notes).
Dec. 8, 1940. The first advertising contract for FM broadcasts was signed by the Longines Watch Company and provided for the broadcasting of Longines time signals by W2XOR, New York, for 26 weeks beginning January 1, 1941. [Dec. 8 is the date from Famous First Facts; according to Broadcasting the date was Dec. 9.]
Dec. 18, 1940. W1XER Boston (Yankee Network) goes on the air as an FM station with 1 kw, transmitting from Mount Washington, according to Donna Halper. This station had previously been a 500-watt weather bureau station (W1XOY), which John Shepard converted to his second FM station.
Jan. 1, 1941. Commercial FM broadcasting is authorized to begin on this date on 42 to 50 MHz (although five frequencies are reserved for educational broadcasting).
Jan. 1, 1941. New York Times lists: 42.8 W2XMN; 43.5 W2XOR; 43.2 W2XQR
Jan. 14, 1941. W2XMN discontinues rebroadcasting programming of CBS, which plans its own New York FM station. W2XMN arranges a regular daily schedule of 10 hours of recorded music originating from the Associated Recording Studios.
Jan. 15, 1941. W1XOJ increases power to 50,000 watts.
Feb. 1941. Non-commercial WBOE Cleveland OH becomes an FM station.
Mar. 1, 1941. W47NV Nashville becomes the first station to be licensed for commercial operation, on 44.7 MHz with 20 kw. This station went off the air in 1951. [As stations are licensed for commercial operation, their calls are changed to a new alphanumeric system which indicates the frequency and location.]
Mar. 1, 1941. New York Times lists: W2XMN 42.8, W2XQR 43.2, W2XOR 43.5, W2XWG 45.1
Mar. 10, 1941. KALW is licensed to the San Francisco Unified School District, the first FM station in the western U. S.
Apr. 1, 1941. W2XOR license replaced with commercial license W71NY 47.1
Apr. 29, 1941. W1XOJ Paxton MA call changed to W43B
May 26, 1941. The first commercials exclusively for FM, for the Socony-Vacuum Oil Co., are broadcast over W43B and W39B.
July 1, 1941. New York Times lists: 42.8 W2XMN; 47.1 W71NY; 48.7 W2XQR.
Sept. 1, 1941. KALW broadcasts its first program, "Schoolcast," after 30 days of experimentation, according to Mullany, George G., "San Francisco Experiment in Radio Education," California Journal of Secondary Education, Oct. 1941, pp. 336-9.
Sept. 5, 1941. W75C Chicago (Moody Bible Institute) is authorized to operate on 47.5 MHz with a power of 1000 watts, using a Western Electric 503-1 transmitter [according to a document with this date seen by Bob Caithamer, Director of Engineering for Moody Broadcasting].
Oct. 12, 1941. New York Times lists: 42.8 W2XMN, 45.1 W2XWG, 47.1 W71NY, 48.7 W2XQR
Nov. 3, 1941. WCAU-FM begins transmissions, according to a WCAU memo dated August 2, 1946 from George Lewis, Assistant Chief Engineer. [Call letters were probably W69PH at the time.]
Dec. 8, 1941. Time reports first FM net: W71NY New York, W2XMN Alpine, W53PH Philadelphia, W65H Hartford, W43B near Boston, W39B Mt. Washington, W47A Schenectady
Feb. 1942. FM magazine reports, "K45LA, Los Angeles, Don Lee station on 1,700-ft. Mt. Lee gets its programs over a 4-mile, 15,000-cycle line from the Hollywood Studios. Western Electric transmitter puts 1 kw. into the Lingo antenna shown here. Power will be increased later. Meanwhile, listeners from San Diego to Ventura are becoming FM program enthusiasts. Station is programmed independently, taking only high spots from Mutual and Don Lee nets.
Feb. 1942 FM magazine reports: "There are now 29 FM broadcast stations on the air with daily schedules. They are distributed as follows: Baton Rouge, 1; Boston, 1; Columbus, 1; Evansville, 1; Los Angeles, 1; Milwaukee, 1; Mt. Washington, 1; Nashville, 1; Rochester, 1; Detroit, 2; Hartford, 2; Philadelphia, 2; Pittsburgh, 2; Schenectady, 2; Chicago, 4; New York City, 6.”
Feb. 1942. FM magazine reports, "Metropolitan Television, Inc., affiliated with Bloomingdale's department store, has been granted an extension until June 30, 1942, to complete construction of W75NY.”
Feb. 1942. FM magazine reports, "An FM CP has just been issued to Amarillo Broadcasting Corporation for 45.1 mc. This application has been pending for many months.”
Feb. 1942. FM magazine reports, "FM application of American Network has been designated for a consolidated hearing which will include seven applicants in the New York area.”
Feb. 1942. FM magazine reports, "W53PH, operated by WFIL, put its full-power transmitter on the air February 10th. This is a 10-kw. R. E. L. installation. FM studios are in the Widener Building.
Feb. 1942. FM magazine reports, "Leonard Ash, president of Capitol Broadcasting Company, Inc., has straightened us out on the ST link situation. Yankee Network's link transmitter operating on 133.03 mc., was the first FM type to be installed. However, Capitol's transmitter was the first to be put into commercial service in the new 331 mc. band. It operates over an airline distance of 12 miles.”
Feb. 1942. FM magazine reports, "Zenith Radio Corporation, operating W51C, has received a letter from a listener in Monterey, Mexico, telling of daily reception of this station between 3:00 P. M. and 6:00 P. M. This is the greatest distance, 1,100 airline miles, from which consistent reception of the 50 kw. transmitter has been reported.”
Mar. 1942. FM magazine reports, "The FM end of the GE broadcasts are originating at W47NY, from which they are picked up on W2XMN, and distributed on FM frequencies to W65H, and north to W43B and W39B, to W2XOY and W47A, and to W53PH. The program is transmitted on Tuesdays, Thursdays, and Saturdays at 6:30 to 6:45 p.m. on the FM stations, and at 6:00 to 6:15 P. M. on the 51 CBS stations.”
Mar. 1942. FM magazine reports, "From this eminence at 500 Fifth Avenue, New York City, CBS is now maintaining a regular FM program schedule. When the antenna is completed, the 3-kw. G. E. transmitter will cover 12,000,000 listeners. Meanwhile, with a temporary antenna, W67NY is putting out a splendid signal, and adding greatly to the entertainment of listeners in the New York area.”
Mar. 1942. An article by Arnold Nygren, chief engineer of WFIL-W53PH, Philadelphia, in FM magazine, reports that W53PH is using a 10-kw REL type 520 DL transmitter and a 50-foot four-bay Lingo antenna on top of a 250-foot tower on the roof of a 255 foot building. The article also reported that beginning in January 1942 W53PH inaugurated a monthly program booklet, and that over 1,300 subscribers received the February booklet.
Mar. 1, 1942. New York Times lists: 42.8 W2XMN, 44.7 W47NY, 45.1 W2XWG, 45.9 W2XQR, 47.1 W71NY.
Aug. 1, 1942. New York Times lists: 42.8 W2XMN, 44.7 W47NY, 45.1 W2XWG, 45.9 W2XQR, 46.3 W63NY, 46.7 W67NY, 47.1 W71NY
July 11, 1943. New York Times reports W2XQR has changed to W59NY
Sept. 19, 1943. New York Times lists: 42.8 W2XMN, 43.9 W39NY, 45.1 W2XWG, 45.9 W59NY, 46.3 W63NY, 47.5 W75NY.
Nov. 1, 1943. The unpopular alphanumeric call system is scrapped and purely alphabetical call letters are adopted; W45CM to WELD, W75C to WDLM, W43B to WGTR, W65H to WDRC-FM, W53H to WTIC-FM, W81SP to WBZA-FM, W67B to WBZ-FM, etc.
Nov. 1, 1943. New York Times lists: 42.8 W2XMN, 43.9 WNYC-FM, 45.1 W2XWG, 44.7 WGYN, 45.9 WQXQ, 46.3 WHNF, 46.7 WABC-FM, 47.1 WOR-FM, 47.5 WABF
Jan. 1, 1944. New York Times lists: 42.3 W2XMN, 48.9 (sic) WNYC-FM, 44.7 WGYN, 45.9 WQXQ, 46.3 WHNF, 46.7 WABC-FM, 47.1 WBAM, 47.5 WABF
May 10, 1944. New York Times lists: 42.3 W2XMN, 43.9 WNYC-FM, 44.7 WGYN, 45.1 W2XWG, 45.9 WQWQ, 46.3 WHNF, 46.7 WABC-FM, 47.1 WBAM, 47.5 WABF
July 22, 1944. W9XEK Louisville goes on the air on 45.5 MHz.
The following information was taken from a WHAS station history page:
Jan. 15, 1945. FCC announces allocations proposals, moving FM to 84-108 MHz, with 84-88 MHz reserved for noncommercial FM broadcasting.
May 21, 1945. FCC announces allocation of spectrum above 25 MHz with exception of 44-108 MHz but delays decision as to placement of FM for propagation studies to be made by FCC and industry engineers. The 44-108 MHz spectrum is to be allocated, following tests, on one of the following three alternatives:
Alternative 1: 44-48 Amateur; 48-50 Facsimile; 50-54 Educational FM broadcasting; 54-68 Commercial FM broadcasting; 68-74 Television; 74-78 Non-Government fixed and mobile aero markers on 75 MHz to remain as long as required; 78-108 Television, fixed, mobile [shared].Middle 1945. For a three month period in mid-1945, WMFM programs were broadcast on both the regular 45.5 mc channel, and on an experimental channel of 91 mc. with reception compared 80 mi away. (Report submitted Sept. 1945)
June 4, 1945. Broadcasting reports FM Broadcasters Association and Television Broadcasters Association ask FCC to allocate: FM 50-54 MHz educational, 54-68 MHz commercial; TV 68-74 MHz and 78-108 MHz
June 27, 1945. FCC allocates 88-108 MHz for FM broadcasting, with 88-92 MHz to be reserved for noncommercial broadcasting, and allocates 106-108 MHz for facsimile broadcasting. Within the 92-106 MHz spectrum, FM stations are to be allocated as follows: 92.1-93.9 community; 94.1-103.9 metro; 104.1-105.9 rural.
Sept. 12, 1945. FCC issues rules for FM broadcasting. Assignments for existing stations in the new band are as follows, with later revisions in parentheses:
Dec. 24, 1945. Broadcasting reports FCC announces tentative allocations plan for FM, providing for over 1500 stations; makes 32 more conditional grants, bringing total to 229
Jan. 10, 1947. On this date 25 FMs are still in the low band.
Jan. 5, 1949. Armstrong obtains temporary restraining order from Washington Circuit Court of Appeals allowing him to stay on 44.1 (brought as a result of July 1946 order eliminating lower FM band)
Apr. 29, 1952. The first multiplex broadcast during regular programming by KE2XCC. A carrier of 25 kHz was used, with a frequency swing of +/- 5 kHz.
Feb. 1, 1954. Edwin Armstrong dies
Mar. 6, 1954. KE2XCC goes off the air. At 7 p.m. the station aired a program in memory of Armstrong; at 8:57 "This is the last program of our 15 years of broadcasting"; Star-Spangled Banner; "As we prepare to pull the switch and shut the station down, we salute the memory of Edwin Howard Armstrong.”
Oct. 12, 1955. The first SCA grants are made to WPEN-FM in Philadelphia and WWDC-FM in Washington.
Apr. 24, 1961. Broadcasting reports the FCC approves stereo multiplex standards.
June 1, 1961. FM stereo broadcasting is authorized to begin.
June 5, 1961. Broadcasting reports that three stations announced they went on the air at midnight May 31 in their respective time zones: WGFM Schenectady at midnight Eastern time, WEFM Chicago at midnight Central time, and KMLA Los Angeles at midnight Pacific Daylight Saving Time. It reported that the FCC granted type approval for stereo broadcasting at 2 p.m. May 31 to WGFM and WEFM.
(According to Dave Obergoenner, KCFM broadcast in stereo at the same moment as WEFM, using a stereo generator designed and built by station Chief Engineer Ed Bench. A history article in Radio World has: “At midnight on June 1, 1961, KCFM made history by simultaneously signing on in stereo with two other FM stations in the nation.” According to a web page, Bench received type approval on Jan. 2, 1961.)
1962. FCC revises FM rules, dividing the country into three zones (instead of the previous two), creating class A, B, and C stations, and adopting power limits for each class.