W6XAO - Los Angeles
One of the most interesting stories in the history of early television is that of Don Lee Broadcasting. Don Lee was a Cadillac dealer in Los Angeles who entered the broadcasting business in 1926 with the purchase of a radio station. In November, 1930, Don Lee engaged the services of 24-year-old Harry R. Lubcke, B.S., University of California, an electrical engineer, and gave him the title of Director of Television of the Don Lee Broadcasting, and applied for a construction permit for the first television station on the west coast, W6XAO.
In 1931 Lee obtained a license for W6XS, which broadcast on a frequency of 2100-2200 kHz, using a mechanical camera that worked only with film. The picture had 80 lines and 15 frames per second. Since there were few commercially available TV receivers at the time, Lubcke prepared and distributed plans for construction of mechanical receiving sets to many amateurs in the area of Los Angeles. The 80 line picture was transmitted on both W6XS and W6XAO.
On December 23, 1931, W6XAO went on the air from the eighth-floor transmitter at Seventh and Bixel streets, Los Angeles, at 44 1/2 megacycles, to broadcast one hour daily except Sundays. This was one of the first VHF stations to go on the air in the United States. W6XAO broadcast the same 80 line picture as W6XS.
Here is a description of the station from the book "The Great Television Race" by Joseph H. Udelson:
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In the Los Angeles area, Don Lee, who owned several California radio outlets and headed a regional broadcast network, began operating W6XS near Gardena in 1931, on the 2100-2200-kHz. channel. In the spring of 1932 the station was moved to the Don Lee Broadcasting System headquarters at 7th and Bixel, in Los Angeles, where in December this video facility, operating in synchronization with radio station KHJ, initiated a regular telecasting schedule from 6:00 to 7:00 p.m. Using a 1000 watt transmitter, an 80-line picture, 20 frames per second, was telecast. The programming consisted of filmed action and closups of motion picture stars. |
In the early 30s Lubcke started experimenting with electronic television. By 1932 he had developed a CRT receiver with self synchronization. . Because Los Angeles had both 50 and 60 Hz electric power, and to facilitate use of CRT receivers, synchronizing pulses were included in the video signal.
As early as 1931 Lubcke had been providing instructions to amateurs to build their own electronic receivers, and kit sets were available from Allied Radio and others. There were many articles in radio magazines about people building their own sets.
In 1932 he demonstrated television reception in an airplane.
In 1933 W6XAO, using "rapid process" film development, telecast news footage of the 1933 Long Beach earthquake to L.A. viewers. This is the first documented evidence of television news coverage. Who knows what the received images looked like on the mechanical sets of the era.
W2XS and W6AXO broadcast the same 80 line images until 1936, when W6XS went off the air. On June 4, 1936 W6XAO began a month-long public demonstration of its new system, using 300 lines and 24 frames per second. The camera was a mechanical flying spot scanner type. One source describes it having "some sort of sine wave vibrating mirror and a Nipkow disk", while the article by F. Alton Everest describes a camera with a large disk. Only filmed material was telecast.
From the above information, we can conclude that the camera worked as follows: The disk spun at 3600 rpm, or 60 rps. To get the rate of 7200 lines per second (24 fps x 300), 120 holes would be required in the disk. As the article says, the holes were all the same distance from the center of the disk. It is not possible to determine the diameter of the disk from the photo, but since it was driven by a 7 1/2 hp motor it must have been quite large. Assuming a disk diameter of 6 feet, the circumference would have been 226 inches. With 120 holes, the holes would have been been 1.88 inches apart. The article says that the holes were #80, which are .0135 inches in diameter. That would allow about 135 hole diameters in the 1.88 inch space, which would roughly translate into the horizontal resolution of the camera. The article mentions that the resolution was improved by aiming the light through the holes at an angle. The screen shots look like about 150 line resolution.
Peter Yanczer commented on the above:
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If it were 6 feet... think about it. The disk circumference of about 19 feet would be rotating 24 times per sec., therefore moving at about 450 feet per sec. This is a little over 300 miles an hour. This gives one an idea of the windage there would be. No doubt this would require an evacuated housing, able to resist the atmospheric pressure on two 6 foot+ diameter surfaces. Air pressure is around a ton per square foot, so you're looking at about 60 tons total on the housing. Maybe I screwed up here? But I wouldn't go this route. It was common practice on cameras to use smaller disks, operating at higher than normal speeds in evacuated housings. if you double the disk speed, the spacing between the holes doubles. On 240L/25P, using a drum, Baird was running them as high as 6000 RPM. The same principal would apply to scanning disks. As for how Lubeck accomplished it, Possibly he also had some optical techniques as well. There are ways. I also wonder about this business of running the light source on a slant to improve resolution. With a scanning disk, that to me seems to present problems. Yes, I have to wonder. |
Actually, the disk would be rotating at 60 times per second, making the speed at the edge about 1150 fps, approaching the speed of sound.
Harry Lubke with monitor equipment (ca 1937)
1938 Program Schedule
DuMont and RCA Iconoscope cameras were obtained in late 1938 or early 1939, and the standard was changed to 441 lines and 30 frames per second, in line with the RCA system. Three sets built by Lubcke in the late 30s survive today. Radio News published an article about Don Lee in 1939. Another article described reception of W6XAO on a home made receiver. W6XAO's plans to change to 441 lines are described in this article.
In 1941 the station changed to 525 lines, and broadcast through World War Two with a limited schedule to the handful of sets in the area.
An early Don Lee camera
W6XAO claims to have broadcast the first soap opera, on April 15, 1938, called "Vine Street".
1939 telecast from the swimming pool located at the new W6XAO studios/transmitter situated on Mt. Lee atop the Hollywood Hills
W6XYZ claimed that their 1943 remote telecast was the first on the west coast. However, W6XAO was actually first with a live telecast of the Tournament of Roses Parade on January 1, 1940.
Telecast from about 1939. The camera was made by RCA.
Rear view of Don Lee camera (ca 1939)
1942 Don Lee Iconoscope camera
This picture is allegedly of the first television commercial on the west coast. The photo has a handwritten date of 1935 on it, but it must be from 1939-41, the period during which W6XAO had the RCA camera shown in the photo above this and in this photo. In the picture is Burton Pfeiffer, making a television commercial for Kenwood Blankets.
1940 Article
The caption on this picture reads "The internationally noted theatrical producer Max Reinhardt, is shown as he made his television debut Nov 9 (1939). He is shown with Ann Lee, an actress, when the producer and his company appeared in scenes from "On Human Bondage" telecast from the Thomas S. Lee station, W6XAO, only television station in the west."
From Radio & Television, July 1940
From Radio & Television, August 1940
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Late 30s test pattern |
1944 Los Angeles phone listing (Courtesy of Steve Dichter) |
1939 Plans for Studio and Transmitter Building
The W6XAO antenna with building housing transmitter and studio in 1941
Plans to add FM sound. From Radio & Television, July 1941
On May 6, 1948, the station was granted full commercial status. On becoming a full commercial operation the station adopted the call letters KTSL-TV. It was acquired by the Columbia Broadcasting System January 1, 1951, and ten months later, the call letters were changed to KNXT to coincide with CBS Radio Station KNX.
A postcard showing the Don Lee Broadcasting building in 1949
Many of the pictures above their captions were generously provided by Steve Dichter. More on Don Lee can be found in the Robert L. Pickering's article titled Eight Years of Television in California. Ed Reitan provided an account the history of Don Lee television. More information is provided in a description of W6AXO in 1942 by Al Germond. More W6XAO pictures from a 1944 book "Get Ready to Sell Television."