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CT-100 -> TV tuner
Since my 15GP22 is dead, I've finally decided to break down and do
what I've been threatening since it happened. I am going to turn my CT-100 into a color TV tuner that will feed any standard CRT or LCD TV monitor. This is so I can watch TV with CT-100 quality decoding. As a glorious stunt. The video will of course be easy. I'll just DC couple the CRT drives into some op-amps and adjust the level and gain. Sync will need a bit of work but will be equally straightforward. The biggie from my point of view is the HV. Without a CRT there is no need for it. If I do nothing the poor regulator tube will sit there overloaded and generating Xrays. So I will unplug the HV and focus rectifiers and the regulator. Without these the pulse amplitude from the flyback will go far too high. One can't remove the horizontal output tube or the AGC and horizontal sync won't work at all. So I want to get the pulse level and therefore boost voltage well below spec, like half or 2/3, so the pulses will work the AGC and sync OK. Turning down (or up) the horizontal drive is not really useful as it does not change DC bias. Two others method would be to increase the output tube cathode resistor, currently 12 ohms, or its screen resistor, currently 2.2K. Would it matter which I did? Or would using whichever was easier to do be OK? Or should I just plug in a 6BG6, which is pin and rating compatible but has about 1/2 the current at a given grid-plate voltage? You advice on this is sought. |
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