Videokarma.org TV - Video - Vintage Television & Radio Forums

- Early B&W and Projection TV (http://www.videokarma.org/forumdisplay.php?f=19)

- - High Voltage Transformer (http://www.videokarma.org/showthread.php?t=264084)

Quote:

Originally Posted by zeno (Post 3132157)

Why a scope tube ? I would think retention would be
a problem with it.

The P1 green oscilloscope phosphor has about the same persistence as the white P4 television phosphor.

The ones that would be a problem would be the long persistence radar screens (P7), or the very short persistence types (P15, P16) used for flying spot scanners.

Quote:

Originally Posted by bhegges (Post 3132055)

I am looking at building an all tube television and have some questions about the high voltage supply. In looking at some of the early designs a 1b3 diode was used in conjunction with a beam pentode oscillator. My understanding is that the beam pentode would feed a high frequency into the primary transformer winding and thus creating the high voltage secondary to feed the 1b3. I am thinking of using an oscilloscope tube and will probably need 2-6kv depending on the tube.

Bhegges, with only 4 posts here at this time one could think that you are new to this sort of things. I see now that you have already built a TV monitor using a 7JP4!
At any rate, I happened to find a article on an unusual HV supply. Only a little over 1 KV, useful for a scope CRT. It uses a series resonate L-C combination to generate about 500VAC, then uses a voltage doubler with a pair of 1B3's to produce about 1200 VDC.

Thanks everyone for your posts. I have been a passive member for quite some time and have always enjoyed seeing what everyone has been working on, my only posts were to share my tv project, a 7jp4 monitor. I have since sold it and now have started tinkering with electronics again and thought I might try my hand at another all tube crt. I would not have to go with a oscilloscope tube but I was looking for something that did not have too high of voltage needs. From the sounds of the replies the "brute force" is no better.

Thanks again,