As aforementioned, the first televisions were experimental types of apparatus, generally using mechanical scanning system.
Around 1939, the industry launched in the market the first all electronic television receivers. They had updated audio section similar to the circuit topology used currently for radio receivers as well as a high gain, good image rejection ratio channel TV tuner, allowing tuning by touch pad or rotary switches up to three channels.
In spite such technological advancement; the televisers were still using optical systems to project the image on a large glare proof glass screen to compensate the small circular area - 5 to 10 inches - of the primitive cathode ray tubes.
(a) The television receiver concept circa 1920. (Radio News, May 1926) (b) Console type of televiser and readio-receiver using image projection system made in the USA circa 1932.
(d) illustrations of diverse types of primitive television sets (collection Steve McVoy, U.S.A.)
(a) The concept of the television in the beginning of 1920. (News Radio, May of 1926) (b) Console composed of radio-receiver and television set using system of image projection, American, manufacture in 1932. c) Type of console composed of the radio-receiver and television and record players manufactured by Fischer Radio Corporation in 1940.