[Penthode]

As I was watching and seeing how soft the video was, I was reminded of a story the late Ken Davies from the CBC told me some years ago. He was working in the '50's on a new CBC microwave cross Canada network link employing full video bandwidth links. That is links which would pass the full 4MHz plus video signal. Ken said at the time the AT&T links used across much of the US were bandwidth limited for many years to no more than about 3.0 to 3.5MHz, which could not carry the full color video signal. To circumvent the link limitations, a process was used to hetrodyne the chrominance signal and subcarrier to around 2.6MHz for the link and then hetrodyned back to 3.58MHz at the receiving end. Of course much of the high frequency luminance information would be lost which would result is soft video.

Ken said the degradation was quite noticable which explained the extra effort CBC put into the wideband link leading up to Canada beginning NTSC color in 1966.


I believe the Playhouse 90 recording reveals many things about the state of the technology at CBS in those early color days.The live studio production in NYC was fed via AT&T microwave link to Television City in Los Angeles where this recording was made. This is my take on further aspects of the color videotape:

1. This live Playhouse 90 production from NYC appears to have used only two TK41 cameras evident by the frequency of the impaired (Pink) camera useage. It looks like the cameras were alternated.

2. The studio switching was very basic: there did not appear to be any split screen or dissolves because I still think it was beyond their color capability at the stage.

3. The color keying was a separate piece of hardware.

4. The apparent bad edits: I suspect this was before the process of the use of the chemical identification of the control track pulse on tape with mechanical splicing. However the CBS Engineers thought it was probably good enough as viewed on a monitor. The monitor scanning timebases would rapidly re-phase so that the splices would not be noticeable. What I do not think the CBS Engineers anticipatedt was how the Ampex Color VTR at Television City Los Angeles would handle it! I believe the NYC splices played havoc with the Ampex capstan and quad head scanner servos. The inherent inertia would track time to find proper phase.