Quote:
Originally Posted by bandersen
..2.71 volts with 117 on the ac line. Ideally I want 0.15 amps flowing through that shunt.
|
I'm gonna stick my neck out a little bit here.
Ideally, and for longevity's sake, i would run the CRT heater voltage as low as possible consistent with a nice bright picture (irrespective of what current is flowing thru the shunt resistor.
The logic behind this is that the 2V Predicta guns were notorious for going flat prematurely.
Other discussions have mentioned voltages ranging from about 2.25V to 2.5V as being appropriate.
I would experiment with adding a little more shunt resistance, say a hundred ohms at a time, across the 18 ohms you've already got there. And see how low the heater can be run and still give a bright pic.
The name of the game is preserving emission in a CRT that's probably irreplaceable.
Quote:
I'm curious as to how they could make an electron gun that runs on only 1.2 W (2.68 volts * 0.45 amps) that works as well as one that runs on 3.8 W (6.3 volts * 0.6 amps) ?
Did they use improved cathode material or is there some downside like shortened life ?
|
2V Predicta CRTs generally had
drastically short life, even when bought new.
Does anybody know for sure the logic behind the 2V guns?
