On Sun, Jun 20, 2021 at 11:23 AM Holm Tiffe via cctalk <cctalk at classiccmp.org> wrote: Those tubes are _very_ hard to find as a spare part. They are, of course, electrostatically deflected and the deflection angle is a lot larger than normal. This leads to poor linearity, which is why 'scope tubes have a small deflection angle, but of course that doesn't matter for a digit display. Just about the only source is another HP9100 (it's the same tube in the -A and -B models) but of course it is not a good idea to raid a repairable machine for the CRT. And a word of warning. If the tube has received enough force to crack the envelope ( hence air gets in and the getter oxidises to white) it's likely the glass rods that support the electrodes have cracked too. This leads to shorts between the deflection plates and the high-voltage anode. If this has happened and the machine has been powered up like that, then there are very likely to be blown transistors and diodes all over the place. -tony