Hi ! The thin material used to maintain the cathode, grids and plate inside the tube is calles mica. It is a mineral that has been pressed into sheets, and was used to make heat resistant windows or thermal insulators. It is also a good electrical insulator, used as dielectric in precision "silver/mica" capacitors
Thank you, I knew it was made of something unique, especially with how it came apart, but I couldn't figure it out while I was dismantling everything. And then I got sidetracked with the weirdness of the Thyratron, haha. That's awesome that it's the same type of material as used in mica caps. Apparently, little mica insulating sheets were used in Microwaves too, because you can order a pack of like 1000 for $10 on Amazon, haha.
@@UsagiElectric Thin mica sheets were commonly used to electrically insulate components from a heatsink. They are still readily available, but silicone pads are more common now since they don't require thermal grease. I still prefer mica since it has slightly less thermal resistance, but the grease does make a mess.
@@rocketman221projects Thanks, I knew I had recognized them before! It's interesting to see how differently they've become with 40 years of R&D. The ones on the tube were surprisingly thick and actually had a reddish reflection to them. Heatsink insulators that I've pulled out of more modern equipment seem to be much thinner and are much clearer. Still, it's awesome to clearly see a materials science lineage here!
Fun fact: mica sheet is directly produced from naturally occurring minerals by sorting, cleaving and cutting to shape. You basically pick a rock, ply it apart and put it into a vacuum tube or onto a heatsink.
@@sashimanu mico was also used for small windows in coal burners and oil burners because it is resistant to high temperatures, so you can check the fire. It is indeed still sold as to3/to22 isolation plates for mounting transistors on a heatsink
Wow. Thank you so much for posting the video. I have always wondered how the vacuum tube works and it actually looked like inside. Now I know the inner structure really clearly. The symbol for vacuum tube was just a cross section. Very cool!
Thank you so much for checking the video out! I love the vacuum tube symbol because it's just about the most representative symbol of what's actually going on inside!
One trick for cutting glass tubes like the ones the vacuum tubes are in: once you make a groove around it with a file, wind a nichrome wire in that groove and then pass a current through it. The wire will become hot, the glass under it will expand and break off cleanly.
The insides of vacuum tubes are so fascinating! I once bought a GU-81 triode off of eBay for a tesla coil, but I cracked one of the pins trying to put it in the socket. It aired out and my tube was now useless. Anyways, it was a good excuse to look at the insides. Those power tubes are built so well. I have a pair of 10kW transmitter tubes, it would be cool to take a look inside one of them sometime, but they are too valuable to break.
I love that you can just so clearly see all the individual components. I mean, you can kind of decipher silicon, like Ken Schiriff does on his blog righto.com, but it's not quite the same as being able to see it with the naked eye! I need to get my hands on one of those GU-81 triodes, they're absolutely massive! The only problem with those old school power triodes is that I don't even have a power supply on hand strong enough to just drive the filaments, much less to anything useful! Still, what beautiful pieces of equipment. I bet those 10kW tubes are amazing looking too!
Love your videos. Vacuum tubes may live and last a long time but not so with electrolytic capacitors turned resistors like the multi-sectional types in the cans.
Thank you so much! Those old wax capacitors you often see in radios are notoriously bad! We have an early '60s Magnavox Concert Grand and it had some of those caps that had bit the dust and were preventing the whole thing from working. After a re-cap, the original tubes fired right up and it puts out one of the best sounds I've ever heard!
That translucent foils non conductive stuff that held everything in place in the 12BH7 could be mica. Edit: sorry I commented while watching the video and didn't realized that an other one already said the same thing.
Haha, yup! Kind of a case of the "wrong tool for the job," but I'm also a firm believer in "if it's crazy but it works, then it isn't crazy." Those old Magic Eye tubes were absolutely awesome! We have an old 1960's Magnavox Concert Grand Radio that my Grandpa bought new, and aside from putting out the best sound of any stereo I've ever heard, it has one of those Magi Eye tubes. I would love to dissect one some day! Here's the radio: i.postimg.cc/RV9dFcwj/IMAG2442.jpg And the Magic Eye: i.postimg.cc/Gm8Dk44Z/IMAG2441.jpg
At 8:05, evidently my wife was a "control grid" in a previous life because she is very tightly wound. She also has some characteristics of a suppressor grid as well....😅😳😖
Very cool. I wish your camera focused on the tube in your hands rather than being fixated on the straight lines in the diagram below the disassembly. I guess this is where manual focus works much better.
Thank you! Actually, the camera doesn't have active autofocus. It's really just a cheap Canon Rebel T5 DSLR that I'm forcing into use as a video camera. So, when I set the focus, I totally didn't think about my hands picking the tube up and pulling it out of the plane of focus. Unfortunately, the process I was doing was totally destructive, so I couldn't re-film without having to destroy more tubes, so I just lived with the poor focus and instead hoped that the Macro shots would make up for it. I'm still working on getting better with using this particular camera and getting shots to look good, hopefully the quality of the videos is improving with each new one I make!
@@UsagiElectric Hey, now worries at all. I'm so used to seeing people struggling with autofocus it's actually refreshing to find someone that doesn't use it :-) Thanks for taking the time to respond!
A diamond coated file or diamond cutting disk (like a Dremel tool diamond wheel) would have been faster for cutting/removing the glass. You probably should have worn a mask and gloves while scattering powdered glass into the air! Also, assuming that you used the same file to cut all the tubes open, you probably dulled it on the first tube and so it didn't cut as efficiently when you got to the 6au6.
I did some checking on use of Plastic it tubes, Mica the best plastic producs off gases when heated . Not good for a tube. Unless your making Special tubes that would be vacuum then filed with a noble gas like Argon.
Ooh, I hadn't actually thought about that! I also just so happen to have a dead 12BH7 hanging about that I dropped, so that'll be a good candidate for this. I'll have to give that shot one I manage to get ahead on work (been swamped busy lately with translation for work).
Hi ! The thin material used to maintain the cathode, grids and plate inside the tube is calles mica. It is a mineral that has been pressed into sheets, and was used to make heat resistant windows or thermal insulators. It is also a good electrical insulator, used as dielectric in precision "silver/mica" capacitors
Thank you, I knew it was made of something unique, especially with how it came apart, but I couldn't figure it out while I was dismantling everything. And then I got sidetracked with the weirdness of the Thyratron, haha. That's awesome that it's the same type of material as used in mica caps. Apparently, little mica insulating sheets were used in Microwaves too, because you can order a pack of like 1000 for $10 on Amazon, haha.
@@UsagiElectric Thin mica sheets were commonly used to electrically insulate components from a heatsink. They are still readily available, but silicone pads are more common now since they don't require thermal grease. I still prefer mica since it has slightly less thermal resistance, but the grease does make a mess.
@@rocketman221projects Thanks, I knew I had recognized them before! It's interesting to see how differently they've become with 40 years of R&D. The ones on the tube were surprisingly thick and actually had a reddish reflection to them. Heatsink insulators that I've pulled out of more modern equipment seem to be much thinner and are much clearer. Still, it's awesome to clearly see a materials science lineage here!
Fun fact: mica sheet is directly produced from naturally occurring minerals by sorting, cleaving and cutting to shape. You basically pick a rock, ply it apart and put it into a vacuum tube or onto a heatsink.
@@sashimanu mico was also used for small windows in coal burners and oil burners because it is resistant to high temperatures, so you can check the fire. It is indeed still sold as to3/to22 isolation plates for mounting transistors on a heatsink
Wow. Thank you so much for posting the video. I have always wondered how the vacuum tube works and it actually looked like inside. Now I know the inner structure really clearly. The symbol for vacuum tube was just a cross section. Very cool!
Thank you so much for checking the video out! I love the vacuum tube symbol because it's just about the most representative symbol of what's actually going on inside!
One trick for cutting glass tubes like the ones the vacuum tubes are in: once you make a groove around it with a file, wind a nichrome wire in that groove and then pass a current through it. The wire will become hot, the glass under it will expand and break off cleanly.
That's fascinating to see up close. Neat!
The insides of vacuum tubes are so fascinating! I once bought a GU-81 triode off of eBay for a tesla coil, but I cracked one of the pins trying to put it in the socket. It aired out and my tube was now useless. Anyways, it was a good excuse to look at the insides. Those power tubes are built so well. I have a pair of 10kW transmitter tubes, it would be cool to take a look inside one of them sometime, but they are too valuable to break.
I love that you can just so clearly see all the individual components. I mean, you can kind of decipher silicon, like Ken Schiriff does on his blog righto.com, but it's not quite the same as being able to see it with the naked eye! I need to get my hands on one of those GU-81 triodes, they're absolutely massive! The only problem with those old school power triodes is that I don't even have a power supply on hand strong enough to just drive the filaments, much less to anything useful! Still, what beautiful pieces of equipment. I bet those 10kW tubes are amazing looking too!
Isnt the gu-81 a pentode?
Love your videos. Vacuum tubes may live and last a long time but not so with electrolytic capacitors turned resistors like the multi-sectional types in the cans.
Thank you so much! Those old wax capacitors you often see in radios are notoriously bad! We have an early '60s Magnavox Concert Grand and it had some of those caps that had bit the dust and were preventing the whole thing from working. After a re-cap, the original tubes fired right up and it puts out one of the best sounds I've ever heard!
You like vacuum tubes just as much I do thank very much for your work amazing dedication!!
Thank you for checking the videos out!
I am indeed a fiend for vacuum tubes!
Thank you. That is helpful for me. I love the tubes
The little "halo" wire at the top is where the getter was fired off.
Anode cans were blackened to reject heat by infrared radiation so they can stay cooler and have less secondary emission
That's interesting! I never would have thought it was for radiating heat from the kinetic energy of the electrons striking the plate!
there's even a 1930s patent for it :)
Also thank you I had zero clue what the inside looked like!
Thanks for checking the video out! I learned a lot of really cool stuff with this one too!
Mica was used to hold everything together.
That translucent foils non conductive stuff that held everything in place in the 12BH7 could be mica.
Edit: sorry I commented while watching the video and didn't realized that an other one already said the same thing.
Metal lathe? Awesome! I cool tube I remember was a magic eye in a 1940’s long/short/am radio 😊
Haha, yup! Kind of a case of the "wrong tool for the job," but I'm also a firm believer in "if it's crazy but it works, then it isn't crazy."
Those old Magic Eye tubes were absolutely awesome! We have an old 1960's Magnavox Concert Grand Radio that my Grandpa bought new, and aside from putting out the best sound of any stereo I've ever heard, it has one of those Magi Eye tubes. I would love to dissect one some day!
Here's the radio: i.postimg.cc/RV9dFcwj/IMAG2442.jpg
And the Magic Eye: i.postimg.cc/Gm8Dk44Z/IMAG2441.jpg
I think you called the mica washer as plastic at 6.39?
At 8:05, evidently my wife was a "control grid" in a previous life because she is very tightly wound. She also has some characteristics of a suppressor grid as well....😅😳😖
Very cool. I wish your camera focused on the tube in your hands rather than being fixated on the straight lines in the diagram below the disassembly. I guess this is where manual focus works much better.
Thank you!
Actually, the camera doesn't have active autofocus. It's really just a cheap Canon Rebel T5 DSLR that I'm forcing into use as a video camera. So, when I set the focus, I totally didn't think about my hands picking the tube up and pulling it out of the plane of focus. Unfortunately, the process I was doing was totally destructive, so I couldn't re-film without having to destroy more tubes, so I just lived with the poor focus and instead hoped that the Macro shots would make up for it.
I'm still working on getting better with using this particular camera and getting shots to look good, hopefully the quality of the videos is improving with each new one I make!
@@UsagiElectric Hey, now worries at all. I'm so used to seeing people struggling with autofocus it's actually refreshing to find someone that doesn't use it :-) Thanks for taking the time to respond!
A diamond coated file or diamond cutting disk (like a Dremel tool diamond wheel) would have been faster for cutting/removing the glass. You probably should have worn a mask and gloves while scattering powdered glass into the air! Also, assuming that you used the same file to cut all the tubes open, you probably dulled it on the first tube and so it didn't cut as efficiently when you got to the 6au6.
That MICA not plastic for the cover/top.. 6au6 is most likely pyrex for the glass
Yup, a few other commenters pointed that out too. It's super interesting and explains why it broke apart in a really weird manner!
I did some checking on use of Plastic it tubes, Mica the best plastic producs off gases when heated . Not good for a tube. Unless your making Special tubes that would be vacuum then filed with a noble gas like Argon.
You can actually slide the fillament, (heater), out of the cathode. It's very brittle, but worth a look.
Ooh, I hadn't actually thought about that! I also just so happen to have a dead 12BH7 hanging about that I dropped, so that'll be a good candidate for this. I'll have to give that shot one I manage to get ahead on work (been swamped busy lately with translation for work).
i watched this on a tube... monitor