A Tour of the Tektronix Ceramic CRT "Catacombs"

https://vintagetek.org/tour-crt-catacombs/

by dangle1 • 3 years ago

77 34 3 years ago

CamperBob2• 3 years ago

And for extra geek cred, get your calendars here! https://vintagetek.org/2024-calendar/

aurizon3• 3 years ago

I recall some radars used those large round screens, long persistence phosphors. Often these were mechanically rotated in time with the antenna, with slide contact rings. Later electronic rotation superseded that.

dtgriscom• 3 years ago

Tektronix was famous for actual storage screens, where once a signal was drawn across the CRT it would persist until the screen was reset. Very handy for capturing a single event and viewing it at your leisure.

https://en.wikipedia.org/wiki/Storage_tube

ddingus5• 3 years ago

Those computers were fun to use!

The one I used had a joystick built right into the keyboard, and it ran a CNC programming environment.

Data I/O was paper tape via serial and data cassette. Ours did not have the floppy or fast refresh graphics options.

2048x2048 vector space! The big CRT could resolve most of that when well tuned.

The work process was:

Load editor from tape cartridge

Type it in, or read text from paper tape.

I had punched a fair number of shortcut G-codes and I would use them to get the bones of a new program started.

Write finished program text (g-code) to paper tape. That could and should include comments. (We put a setup sheet on the master tape, for example) This was a master.

Make another stripped down one, and this is production.

Prep a tape for reading by sticking the beginning of program end into the reader and put the reader into handshake mode.

Read it back to validate against program in RAM.

Or...

Load backplotter/ simulator. Prep program tape for reading.

Run the simulator, plotter. If it was a master tape, it would know the tooling setup and just draw all the operations to the CRT. And because it was a storage tube, those all would display and one could see what metal gets cut out easy enough.

This worked fairly well!

Once it was done, the production tape went into a can and was moved to a library. That was a whole wall of cabinets filled with little plastic canisters containing paper tape programs for everything.

1Mhz 6500 CPU.

And like I said, the Tek terminals were just fun to use.

MadnessASAP2• 3 years ago

Expansion on your fun fact. Electronic rotation was accomplished with a polar CRT. A polar CRT is a variant of a vector CRT where the beam path starts in the center and extends to the edge in a direction derived from the azimuth of the radar antenna. The transmit pulse would start a new scan from the centre and its speed would be determined by the desired range selection. Finally the beam intensity was just the amplified return signal from the antenna.

All of this required complex electromechanical devices to generate (and eventually filter) the required signals.

As technology progressed and textual information started to be added to the process it became necessary to convert the polar plot to a conventional rasterized signal. This was accomplished with a scan converter tube which was essentially a polar CRT coupled to a TV camera. Radar would plot on the CRT and the camera would turn it into scanlines to be overlaid with data. This was used into the 90s and there's probably still operational systems relying on this.

ddingus5• 3 years ago

In the 90's I got an inside tour of PDX airport.

They had these systems and a camera pointed right at one to rasterize them.

At the time, a whole lot was still analog. Beautiful systems.

Saw one of those 9 track tape drives too. On a seek, tape would just dissappear from one reel and accumulate on the other one --fast!

And then CLACK! It would stop and just start reading at what looked like normal speed. Was kind of impressive in its own way too.

ganzuul• 3 years ago

More information on the ceramic to metal bonding technique would be very much appreciated! I'm looking to accomplish a variation of the kintsugi technique for an art project.

ChuckMcM2• 3 years ago

Okay, that's pretty neat making them out of ceramic. I would love to see the entire process from mold to finished product. I'm guessing the painted the phosphor on to a glass square and then melt/welded it to the ceramic molded tube. I would further guess a similar process was used to attach the electron gun at the back while drawing a vacuum.

I did not know that you could make a tube that way!

13of40• 3 years ago

Here's the process: https://youtu.be/G0Dci5RPe94

I didn't get to watch it to the end yet, but it shows the pressing and firing process halfway through.

ChuckMcM2• 3 years ago

That was awesome! Not surprised at all that these tubes were super expensive, especially with a palladium + gold interior coat :-).

Sunspark• 3 years ago

I think there is still a market for CRTs, esp. with retro-gamers. Vector displays in particular.

BolexNOLA2• 3 years ago

Love me some crisp scanlines

dharmab2• 3 years ago

There's certainly a market, but the process of manufacturing and recycling them is difficult to do in compliance with modern environmental regulations. In particular, the leaded glass is problematic to export for recycling.

mrob• 3 years ago

Leaded glass is not required for CRTs. In the case of color CRTs, it was only used for the backs and sides, because x-rays make leaded glass turn brown. The faceplates used barium-strontium glass, which I assume was more expensive. This sample chapter from "Image Performance in CRT Displays" by Kenneth Compton provides some details:

https://spie.org/samples/TT54.pdf

I see no reason why you couldn't make the whole thing from barium-strontium glass.

rickdeckard• 3 years ago

yeah, but I don't think production and sales of CRT-tubes could be called a "market" in an economically sustainable sense today.

If someone would find a warehouse full of Trinitron tubes: Yes, a nice opportunity to cater to a retro-gaming market.

Setting up the production chain to BUILD tubes at scale: Not really.

BolexNOLA2• 3 years ago

It’s also not just about the economics of it, they’re actually kind of dangerous to produce and involve a fair bit of hazardous materials IIRC. Tinkering with them is a good way to stop your heart too.

neilv• 3 years ago

Tektronix is a legendary company, and an anchor of the Silicon Forest.

I owe some early big career breaks to a Tek spinoff company, and to the Oregon Graduate Institute, which Tek had a part in founding.

ddingus5• 3 years ago

Seriously.

Oregon, who has told me they want to see another Silicon Forest happen, would be wise to look hard at Tek. I owe some of my life advances to Tek as well.

tealpod• 3 years ago

Yes, very much true.

I started my career at Tektronix. The famous Gang-of-Four, who initially categorized/identified Software Design Patterns is all started at Tektronix.

jeffrallen• 3 years ago

Counterpoint: I grew up in a suburb south of Portland in the 80's. My first experience with economic uncertainty and the consequences for a family were seeing a friend's father laid off from Tek.

Boom and bust tech companies are not all good for the communities they sprout up next to.

cwillu• 3 years ago

Skip 2 minutes into the video.

fumeux_fume• 3 years ago

Every now and then I'll come across tektronix tested vacuum tubes while searching for amp tubes. It's a pretty cool piece of history to own.

mindslight• 3 years ago

Thanks, I hate it: https://vintagetek.org/knobless-2445-oscilloscope/

baz00• 3 years ago

Philips brought something as abhorrent to production and it sucked.

jacquesm• 3 years ago

Oh that's so neat. Makes me wonder if the CRT in my scope was made using that tooling, they must have had 10's or even 100's of those sets. I hardly ever use it these days but I can't part with it, it's been with me for a good 30 years or so and it still works well when powered up. I also have a much newer LCD based one that sees much more use and that is far more compact.

Neil44• 3 years ago

Intresting, normally with ceramic moulds the mould is very porous and sucks moisture from the ceramic slip which makes it solidify enough to be removed from the mould and fired. Wonder what the process was here.

jdblair• 3 years ago

The narrator explained in the video. Damp ceramic powder was used, and was placed under tons of force while in the mold. The ceramic powder then stayed in-tact when removed from the mold for firing.

A Tour of the Tektronix Ceramic CRT "Catacombs"

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