W9NTP Sampling SSTV Camera

Standard vidicons work very poorly at the slow scanning rates (Excessively high dark current) and the special Westinghouse 7290s were very difficult to obtain. The sampling camera was an attempt to use a standard vidicon at near standard scan rates to obtain an SSTV picture. W9NTP made a special vidicon camera that reduced the vertical scan rate from 1/60 of a second to 1/15 of a second, the SSTV horizontal frame rate. The camera's horizontal scan rate was kept at 1/15750 of a second. The video output was then sampled and held. It was then output and syncronized to the SSTV vertical frame rate. This would produce an SSTV picture rotated 90 degrees, so to compensate, the camera was rotated in the opposite direction to produce an upright image. It was complicated, but this camera was a dramatic breakthrough for SSTV.