Man, the things I think of when I can't sleep! Or what pop in my head when I wake up! Hey, I could have a worse hobby than radio...fortunately, my wife tolerates my enthusiasm, until someone asks me a question, then she'll tell me, "Don't talk their head off!"
Ray Poindexter's book, "Arkansas Airwaves" is a fantastic source of answers to questions such as the above...but you have to read it to find the answers! I think I have that answer:
In late September of 1924, KFMQ had installed a new 500-watt transmitter. The frequency was changed to 1090 kilocycles (kilohertz to you young 'uns!) or 275 meters. So far, I haven't found a reference before that (pp. 52 in the book), and I'll keep digging. Does anyone else have a reference to an earlier usage of 1090 in Arkansas?
Only a few frequencies were allowed by the Department of Commerce for broadcasting; many radio stations had to share time and came to gentlemen's agreements as to when and when not to transmit, taking turns to crank out their broadcast fare. Seemingly, the frequency of choice I noticed most in this and other sources appear to be 833 kilocycles, or 360 meters. In or around the mid- 1920's, th DoC allowed the AM broadcast band to "open up" from 550 to 1500 kilocycles...which I'm sure resulted in a much less-congested radio spectrum and allowed more broadcast time for stations. However, the years that followed show that the DoC, later the Federal Radio Commission, had stations hopscotching all over the band, changing frequencies so fast, you'd need a program to tell the players! But that's another story....
Reminds me of Abbot and Costello's "Who's On First?"
Bud S. (staceys4@hotmail.com)
833 kilocycles, or 360 meters, was the natural resonant frequency of a spark-gap transmitter and antenna system. People used wavelength because it was easy to measure and the concept of frequency had not yet been invented.
ReplyDeleteWhen engineers added audio by inserting a carbon microphone in series with the spark (by then they were using a rotating alternator to strike the spark), the wavelength remained the same. Later, engineers realized that they could modify the antenna system and operate slightly to the side of 833 kilocycles to eliminate local interference. In those days, radios weren't nearly sensitive enough to discover skywave.
Then Syntony was invented, which is the then-revolutionary idea of tuning a transmitter to a frequency and tuning the radio to that same frequency. Stations began to establish operation on a particular frequencies, radios were built using the new-fangled vacuum tube, and things really took off.
In answer to your question about 1090, let me quote from A.J's blog:
"By mid-1938, KTHS operated 6 a.m. to 9 p.m. and shared the nighttime hours with WBAL Baltimore on 1060 kilocycles, although it was licensed for share time hours on 1040 with KRLD Dallas. The 1060 kilocycle channel offered more airtime.
NARBA Treaty frequency re allocations, KTHS from 1060 kilocycles to 1090 kilocycles, at 3 a. m., Saturday, March 29, 1941. The former authorization for 1040 kilocycles (sharing with KRLD Dallas) was dropped at this time."
KAAY still shares 1090 with WBAL at night as well as with XETRA in Rosarita, Baja California, Mexico, by using a very tight nighttime directional antenna pattern toward both stations.
That should be XEPRS-1090 in Rosarita, Baja California, Mexico.
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