They are hard to find for some reason lol. I stumbled upon them by accident even though I was searching for 3RP1's. Mine just arrived today - well packaged and factory sealed boxes. I haven't hooked them up yet, but they are obviously new and look nice so I do not expect any issues.
LOT OF 3 Oscilloscope Vacuum Tube 3RPI-A | eBay <https://www.ebay.com/itm/235029032080> On Wednesday, October 29, 2025 at 12:11:58 AM UTC-4 [email protected] wrote: > Tom, > > Can you post a link to the eBay listing for the 3RP1A tubes? I was not > able to find it searching with the “I” or “1”, looking in both current and > completed listings. > > Thanks, > Randy > > > On Oct 28, 2025, at 6:15 AM, TomJ <[email protected]> wrote: > > > > Forgot to mention - if anyone else is considering a crt clock project, > brand new Chinese 3RP1A tubes are available from US sellers on eBay (3 for > $85 shipped). But they are listed with the letter "I" instead of the > numeral "1" - the eBay search doesn't pick up on that, so they are easily > overlooked. I think these are the same ones that Sphere used to sell. > > On Tue, Oct 28, 2025 at 6:07 AM TomJ <[email protected]> wrote: > >> >> >> On Mon, Oct 27, 2025 at 4:31 PM Mac Doktor <[email protected]> wrote: >> >>> >>> Note that over at the GeigerCounters group talking about building >>> negative HV power supplies can get you banned. A couple of people found >>> that out the hard way after having been warned. The -900V supplies in >>> Geiger counters are grandfathered in, of course, and the currents are very >>> low. >>> >>> >>> >> Certainly, the voltages involved are no joke and can be lethal. CRT >> voltages typically are very low current as well, but I suspect still very >> dangerous. Though it seems a bit >> nanny-state' to ban legitimate scientific discussions - you can just as >> easily discover mortality working on your car or a home appliance. >> >> In any event, I also received a very informative email from the gentleman >> at Sgitheach... My understanding is that the crt tube doesn't really care >> - it comes down how you want to design your circuit. Having the high >> potential at the cathode makes the deflection circuit easier to implement >> because the voltages are lower. BUT, if you desire to incorporate some >> kind of intensity modulation or Z axis, you now have to manage that end >> with high voltages. The end result from a performance perspective will be >> the same. >> >> Thanks for the insight! >> > -- > > You received this message because you are subscribed to the Google Groups > "neonixie-l" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > > To view this discussion, visit > https://groups.google.com/d/msgid/neonixie-l/CAArLthczeXYLQnthL6gLGVEt%3DsTB1P%2B%2BfOzE-bRh82g2gZEmtA%40mail.gmail.com > > <https://groups.google.com/d/msgid/neonixie-l/CAArLthczeXYLQnthL6gLGVEt%3DsTB1P%2B%2BfOzE-bRh82g2gZEmtA%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion, visit https://groups.google.com/d/msgid/neonixie-l/8bbf7557-7e62-4da8-a6cc-543318d4c00an%40googlegroups.com.
