Quote:
Originally Posted by LukeSimon
Side thought: if the chassis is going to use a voltage divider on the focus rail, why even bother with the buck boost transformer? Why not just use a 50meg pot as the focus control?
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It was probably a matter of cost. The 15M focus and convergence pots rated rated for that voltage in the CT-100 are expensive unobtanium. A slug tuned buck boost transformer is cheap.
The 70s Zenith's that used a resistive divider off the HV for the focus used IIRC a 5M pot and kept it on the ground side of things to make a conventional pot viable, and prevent the need for something expensive and exotic.
Tube based focus I usually bypass with a modern diode...It almost always results in a significant improvement even if the original tube was doing well enough not to complain.