Tektronix’s Ceramic CRT Production And The Building 13 Catacombs

As a manufacturer of test equipment and more, Tektronix has long had a need for custom form factors with its CRT displays. They initially went with fully glass CRTs as this was what the booming television industry was also using, but as demand for the glass component of CRTs increased, so did the delays in getting these custom glass components made. This is where Tektronix decided to use its existing expertise with ceramic strips during the pre-PCB era to create ceramic funnels for ceramic CRTs, as described in this 1967 video.

The Tektronix ceramic CRT molds underneath Building 13.
The Tektronix ceramic CRT molds underneath Building 13.

Recently, underneath Building 13 at the Tektronix campus, a ‘catacomb’ full of the molds for these funnels was discovered, covering a wide range of CRT types, including some round ones that were presumably made for military purposes, such as radar installations. These molds consist out of an inner part  (the mandrel) made from 7075-T6 aluminium, and an outer cast polyurethane boot. The ceramic (forsterite) powder is then formed under high pressure into the ceramic funnel, which is then fired in a kiln before a full inspection and assembly into a full CRT, including the phosphor-coated glass front section and rear section with the electron guns.

The advantages of ceramic funnels over glass ones are many, including the former being much harder and resilient to impact forces, while offering a lot of strength for thinner, lighter structures, all of which is desirable in (portable) lab equipment. Although LCDs would inevitably take over from CRTs here as well, these ceramic CRTs formed an integral part of Tektronix’s products, with every part of production handled in-house.

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Hackaday Prize Entry: An Open Source Kiln

For his Hackaday Prize entry, [Matt] is building a small kiln for melting metals and firing clay.  He’s making this kiln out of materials anyone can acquire — dirt and a bit of nichrome wire.

Most kiln builds you’ll find on the Internet use fancy refractory bricks and other materials you may not have in your back yard. [Matt]’s project is entirely DIY, and starts with a large pile of dirt and rocks. Aftter shaking off the sifted dirt, washing the rocks, straining off the gravel, getting rid of the sand, and siphoning off the water, [Matt] has a big bag of wet clay. This clay is mixed with perlite, an insulating, refractory material, molded into bricks, and fired. The result is a brick that looks good enough to be made into a kiln.

[Matt] has already put a lot of work into the calculations required to figure out the heat transfer of this kiln. At best, this kiln is going to take 14 hours to get up to temperature. That’s incredibly slow, but then again, this kiln will be electric, and will only use 1500 Watts. That’s nothing compared to a commercial electric kiln, but it is a build [Matt] designed himself without any outside help, using only parts he can easily acquire. In any event, this is an excellent project for the Hackaday Prize.