More playing with CRTs (Patreon)

With our HP high voltage supplies all repaired, it's finally time to play with the CRTs in my collection. In the photo above, they are just lit by the UV light in the front. Note that some do light up when illuminated by UV, and some don't - they give nothing at all. 

First up is the square tube below on the left, a Tektronix T-5270 tube for the Tek 527 oscilloscope. Note that I am better equipped this time, and now using proper high voltage cabling, connectors, and a 40 kV probe. Getting there.

There are so many electrodes in these tubes! We'll explain them all. The good thing with the 527 tube is that it only requires 4 kV of acceleration, which is almost within reach of my supplies, so we should be able to focus it correctly.

Eric also brought an electron gun, so we'll be able to show which electrode is which.

But once you put all the right voltages at the right places, including the critical 5 kV isolation transformer you see on the left, to prevent the filament from arcing, you are rewarded with your very own Tek-HP oscilloscope.

We then tried the big round tube. It's a Tek T-543, later standardized into the 5ELP denomination. This one needs post acceleration voltage, 10 kV of it. We tried it without the post acceleration at 3 kV, and just got a tiny weak dot. So, the good news is that it works (maybe, it was quite off-center), but I will need to cook up a 10 kV power supply to go any further. That will be interesting.

Then we went the opposite way, and tried a teeny tiny tube, formerly from a CV-89 RTTY FSK decoder from the 1950s. It requires only 2 kV. It's a bit tired from its former military TTY work, but it still works. And it's cute as a button.

And for the grand finale, Eric brought his triple tube oscillo-clock. It's entirely his own hardware and software design, which he did as a learning exercise. I guess that's how he won his TubeTime moniker. Very awesome.

I'm getting the hang of it, and now this CRT stuff feels less scary and complicated than I used to think. Once we understood how they worked, we lit all of these without much difficulty. This will be a fun episode, when I get to it...

Marc