My newest project, Philco 50T-1402 year 1951

[jr_tech]

Originally Posted by dtvmcdonald

That's a Tesla Coil. They are worth at least somewhere near that.

I have two of that exact sort which I bought new in the 70's and used daily for years. They still work.

The standard use was to look for leaks in glass vacuum systems.
You turn it on and hold it near the glass, and see
a purple glow near the leak.

Oddly, the coil that I remember using around vacuum devices (sans medical quack stuff) is still available:
http://www.amazon.com/Electro-Techni...rds=tesla+coil

not affiliated,
jr

[old_coot88]

Originally Posted by jr_tech

Oddly, the coil that I remember using around vacuum devices (sans medical quack stuff) is still available:
jr

We called ours the "cattle prod" and used it exclusively for cleaning the guns in rebuilt CRTs.
(Small nit, but it's technically an Oudin coil.)

[jr_tech]

Originally Posted by old_coot88

We called ours the "cattle prod" and used it exclusively for cleaning the guns in rebuilt CRTs.
(Small nit, but it's technically an Oudin coil.)

Another vendor on Amazon has it right:
http://www.amazon.com/Oudin-Coil-Tes...rds=tesla+coil

"Cleaning" as in spot knocking?

I have heard the term "cattle prod" as well, but the mental picture of cowboys on the range trailing long extension cords behind their horses during "roundup" is just too amusing.

not affiliated,
jr

[old_coot88]

Originally Posted by jr_tech

Another vendor on Amazon has it right:
http://www.amazon.com/Oudin-Coil-Tes...rds=tesla+coil

"Cleaning" as in spot knocking?
jr

Not sure what is meant by spot knocking. But rebuilt CRTs would frequently arc after installation due to less-than-perfect cleanliness by the rebuilder.
The "cattle prod" applied to the pins would cause debri particles inside the tube to incandesce white and fly around, eventually welding themselves in place somewhere, out of harm's way.

[jr_tech]

Originally Posted by old_coot88

Not sure what is meant by spot knocking. But rebuilt CRTs would frequently arc after installation due to less-than-perfect cleanliness by the rebuilder.
The "cattle prod" applied to the pins would cause debri particles inside the tube to incandesce white and fly around, eventually welding themselves in place somewhere, out of harm's way.

Sometimes particles or burrs on the gun parts in a finished CRT would field emit electrons causing brightly illuminated areas on the screen of the tube, even though the electron gun was turned off. Internal arcing was often observed, as well. The "spot knockers" typically used a HV supply to draw excessive current from these burrs to "burn them out" or dislodge them to a place somewhere out of harms way, as you described, eliminating the field emission "spots". Similar process, for sure.

jr

On Philco turn on, my rounded top 50T-1400 fired up (with a gentle variac ramp-up) after sitting un-used for over 40 years, with sound, video, decent HV and Horizontal but very short vertical. Most parts and tubes are original. Philco must have used pretty good parts in these sets.

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