10-11-2016, 12:06 PM
Video amplification was a real problem with the valves available in 1936. It could be done, as it obviously was at the studios, but it was tricky. Hence the search for other methods. This approach with a RF power amplifier looks like making a small transmitter! The 6/6 CRT had a pretty high slope and so didn't need several 10s of volts of video that would be commonplace with later CRTs.
A similar problem arose in the late 1950s when trying to design transistorised TVs. The video amplifier was a problem, needing high voltage and high bandwidth at the same time. Proposals included a power IF stage directly feeding the detector, very much like the 702. Actually this wasn't really feasible, I doubt it was ever seriously tried. The problem was eventually resolved by the AF118, BF178 and so on into the modern era.
A similar problem arose in the late 1950s when trying to design transistorised TVs. The video amplifier was a problem, needing high voltage and high bandwidth at the same time. Proposals included a power IF stage directly feeding the detector, very much like the 702. Actually this wasn't really feasible, I doubt it was ever seriously tried. The problem was eventually resolved by the AF118, BF178 and so on into the modern era.
www.borinsky.co.uk Jeffrey Borinsky www.becg.tv
