Radio-TV Broadcast History
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When broadcasting licenses were first granted in 1921, all stations were assigned a common wavelength of 360 meters (equivalent to a frequency of 833 kHz). This of course would mean that no two stations in the same area could be on at the same time. In December 1921, a second wavelength, 485 m (corresponding to a frequency of 619 khz) was assigned for some special types of broadcasts like weather reports and farm information. But rather than assigning some stations to one frequency and some to the other, the division was made by content, so a station would switch frequencies when it was time to give a weather report.

In September 1922, a new entertainment frequency of 750 khz was added. In theory, 750 kHz was assigned to better quality, higher powered stations. These stations were designated "Class B" outlets, while those on 833 kHz became known as "Class A" stations. About thirty stations nationwide would eventually qualify to use 750 kHz.

By early 1923, it became obvious that two entertainment frequencies were not going to be enough, and a conference was called by the Secretary of Commerce (later to be President), Herbert Hoover. The conference was held from March 20 to 24 of that year, and issued a report recommending an expansion of the band. These recommendations were used as a basis for the new frequency reassignments.

The report contemplated setting up two new classes of broadcasting station, assigning each a frequency range, while allowing a third class of stations that could continue to use the 833 kHz frequency:

  • Class A stations (restricted to power not exceeding 500 watts) would be allotted frequencies between 1000 and 1350 kHz (described in the report in terms of wavelengths between 300 and 222 meters).
  • Class B stations (allowed power up to 1000 watts) would be allotted frequencies between 550 and 800 kHz (described in terms of wavelengths between 545 and 375 m) and between 870 and 1000 kHz (described in terms of wavelengths between 345 and 300 m).
  • Class C stations would be allowed to continue at 833 kHz (360 m), but no new class C licenses would be issued. It was envisioned that over the passage of time, these would disappear by attrition, which is exactly what occurred.

On May 15, 1923, the government started assigning different frequencies to different stations, at 10 kHz intervals. (This was also the beginning of the use of frequency rather than wavelength in assignments in the licenses.) Initially, these went only from 550 to 1360 khz. The frequencies from 550 to 1040 kHz were set aside for Class B stations, while the remaining frequencies were designated for Class A. (Note that this is slightly, but not greatly, different from the recommendations in the report.) Not all stations left the 833 kHz frequency at this time, however, and these stations were designated as Class C. These gradually cut over to frequencies in the 10 kHz-interval setup over the next few years. The most important stations, however, changed frequencies at this time.

Stations changing frequencies at that time[]

The United States Department of Commerce, which oversaw radio licensing at that time, issued monthly Radio Service Bulletins[1] with news on new and altered licenses. The June 1, 1923 issue gave a list which showed stations whose licenses were altered, meaning, in general in this case, those whose frequencies were changed from 833 kHz to something else. Most of these must have changed on May 15, though it is not possible to distinguish between those stations which changed frequencies on the 15th and those whose frequencies were changed between the 16th and 31st. It can be assumed, however, that nearly all, if not all, stations on this list changed their frequencies on the 15th:

Call sign Frequency on June 1, 1923
KDKA 920
KDPM 1110
KDYM 1190
KDZF 1080
KDZR 1150
KFAT 1090
KFAU 1110
KFAV 1160
KFBL 1340
KFDC 1060
KFDO 1210
KFDP 1080
KFDU 1250
KFEP 1250
KFER 1300
KFEV 1140
KFFA 1240
KFFP 1090
KFGL 1280
KFHB 1070
KFHH 1060
KFHR 1110
KFI 640
KFZ 1060
KGW 610
KGY 1160
KHJ 760
KJR 1110
KNT 1140
KOP 1050
KPO 710
KSD 550
KYW 870
WAAB 1120
WAAK 1070
WAAM 1140
WBAN 1230
WBAP 630
WBAU 1160
WBAV 770
WBAW 1220
WBAY 610
WBL 1150
WBU 1050
WBZ 890
WCAE 650
WCAH 1050
WCAT 1250
WCAU 1050
WCAY 1150
WCX 580
WDAF 730
WDAK 1150
WDAR 760
WDAY 1230
WDZ 1080
WEAD 1120
WEAF 610
WEAG 1300
WEAI 1050
WEAM 1190
WFAA 630
WFAB 1280
WFI 760
WGAL 1210
WGAU 1330
WGAW 1150
WGY 790
WHAA 1060
WHAG 1350
WHAL 1210
WHAS 750
WHAZ 790
WHB 730
WIAD 1180
WIAF 1280
WIAJ 1340
WIAK 1080
WIP 590
WJAN 1070
WJAX 770
WJAZ 670
WJD 1310
WJH 1140
WKAC 1090
WKAN 1330
WKAW 1240
WKAX 1300
WLAG 720
WLAH 1280
WLAS 1230
WLAX 1300
WLAZ 1210
WMAC 1150
WMAH 1180
WMAJ 1090
WMAL 1170
WMAP 1220
WMAQ 670
WMAV 1200
WMAZ 1120
WMC 600
WMH 1210
WMU 1150
WNAN 1050
WNAX 1230
WOAC 1130
WOAG 1340
WOAI 780
WOAV 1240
WOAW 570
WOAX 1250
WOC 620
WOO 590
WOR 740
WPAJ 1120
WPAL 1050
WPAZ 1100
WQAD 1240
WQAF 1250
WQAH 1180
WQAS 1130
WRAL 1210
WRAN 1310
WRAR 1330
WRW 1100
WSAH 1210
WSAI 970
WSAL 1220
WSB 700
WSL 1100
WTAS 1090
WTAW 1180
WWI 1100
WWJ 580

Several stations which had been authorized to operate on both 750 and 833 kHz were allowed to keep operating on 833, but eliminated the added 750 kHz frequency. According to the June 1 Radio Service bulletin they were:

References[]

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