Postwar Broadcast Equipment RCA TK-1C Monoscope
The TK-1C monoscope was used by television stations to produce the famous "Indian Head" test pattern. This one was used by WBNS-TV, channel 10 in Columbus, Ohio. It was donated to the museum by Daniel Black.
It uses the 2F21 monoscope tube
This tube was available in two versions, one with a generic pattern, and one with a custom pattern. This one has a custom pattern for WBNS-TV. We will be able to display it once the TK-1C is restored.
I looked at the TK-1C and realized that the electrolytics had been replaced, so I decided to fire it up and see what would happen. I brought up the DC slowly and none of the electrolytics got warm. When I put the full 280 volts on it, a picture emerged.
Here is the image from an Indian Head test pattern from a 2F21 tube:
And here is one from a tube donated to us by Dan in California:
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