Re: Tektronix Neon Light replacement parts?


Cliff Carrie
 

The wires through the glass of a neon lamp are made of Kovar, an iron-nickel-cobalt alloy with a coefficient of thermal expansion similar to that of hard (borosilicate) glass. Kovar is more brittle than copper and may be made more so by the glass processing temperatures. Also, copper connecting wires may be welded to the Kovar leads very close to the glass, all making this a weak area where stress and flexing should be avoided.

You really need to look at the parts list and wiring diagrams for each neon you replace. Tek used them for many purposes besides indicators. You will find neon voltage clamps in scope CRT circuits. They have been used as protection clamps on timebase trigger inputs. Many of these light up only briefly if at all, and will last a long time. Neons left on continuously will age badly. We have all seen power bars with a flickering or dead neon. As they age, the strike voltage and the extinguishing voltage rise very significantly. I have confirmed this with my 7CT1N curve tracer. I have tested photosensitivity; the strike voltage drops by a few volts with bright illumination. Isotope filled neons are supposed to be less photosensitive. There was an NE2-looking voltage regulator in the 3B3 timebase delay circuit (the Philips ZZ1000, about twice as long as an NE-2 and blackened on the inside). Even more exotic was the NE77, a three electrode device that behaves a bit like a thyristor, but I never saw it in Tek gear. I have about 12 pages of 1962 vintage GE catalog information on these and other glow lamps if anyone is interested.

Cliff Carrie
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