Possible Sunset Info for the Saga of Neons for the HP 419A Meter

[gridleak]

I want to leave thses final thoughts on neon lamps for the HP 419A. The only current discussion about those neons ( on groups.io HP forum) revolves around replacing the neons with optocouplers and LEDs. That's the best move. For those of us who are fossils, and won't give up on neons, let me share these observations. If an HP 419A drops in your lap, with dead neons you will NEVER get things working with any arbitrary ne2 style lamp. First, you must use dark effect treated lamps. The NE2H is listed as dark effect treated. Another lamp I have used is the A3C which is dark effect treated and qualified for chopper applications. However, I never got either of these lamps to fire properly in the HP 419A unless I added this circuit  :https://dabbledoo.weebly.com/hp419a.html. The only lamp that worked out of the box was one suggested by a volt/nut subscriber: GT-NE6H1925T. I have used these in my 419 twice with success. I think they work because of "poor quality control" causing enough difference in specs between individual lamps to satisfy the the trigger requirements for oscillation. The GT-NE6H1925T is now unobtainium leaving the additional circuit route as the only way out.

[Conrad Hoffman]

Thanks for that! I have two of them that I need to get after at some point. Always liked the way they worked, sometimes better than my Fluke 845.