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PostPosted: October 30th, 2022, 10:43 am 
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Joined: January 15th, 2015, 7:19 am
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Location: Baltimore MD
Here is a lady that scratch builds tubes.
Actually she is building a 1920's designed tube amp but makes the tubes first.
This is real DIY
https://youtu.be/-UEfqAWb3fE


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PostPosted: October 30th, 2022, 1:52 pm 
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Location: Parkville, Maryland
Pelliott321 wrote:
Here is a lady that scratch builds tubes.
Actually she is building a 1920's designed tube amp but makes the tubes first.
This is real DIY
https://youtu.be/-UEfqAWb3fE

This chick has taken DIY to an entirely different level!!!! WOW!! :o

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PostPosted: October 30th, 2022, 3:11 pm 
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In order to do this there are three things you need:

1. Glass blowing ability (don't inhale)
2. A good vacuum system
3. A knowledge of Cathode chemistry both for directly and indirectly heated cathodes.

The killer is number 2. The National Capital Astronomer's Telescope Making Class at the Chevy Chase Community Center has a vacuum system that is good enough to Aluminize telescope mirrors. I don't know if that is good enough to evacuate tubes. You would need a system with a roughing pump, a diffusion pump, and a cold trap. I do know someone who could answer questions about cathode structures and chemistry if you couldn't find the answers online.


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PostPosted: October 30th, 2022, 3:17 pm 
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Joined: July 8th, 2016, 4:34 pm
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This should also be of interest -

https://hackaday.com/2018/12/31/the-art ... brication/


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PostPosted: October 30th, 2022, 4:40 pm 
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brombo wrote:
In order to do this there are three things you need:

1. Glass blowing ability (don't inhale)
2. A good vacuum system
3. A knowledge of Cathode chemistry both for directly and indirectly heated cathodes.

The killer is number 2. The National Capital Astronomer's Telescope Making Class at the Chevy Chase Community Center has a vacuum system that is good enough to Aluminize telescope mirrors. I don't know if that is good enough to evacuate tubes. You would need a system with a roughing pump, a diffusion pump, and a cold trap. I do know someone who could answer questions about cathode structures and chemistry if you couldn't find the answers online.


When making high power electronic flash tubes, we used liquid nitrogen on the cold trap.


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PostPosted: October 30th, 2022, 5:08 pm 
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Joined: July 8th, 2016, 4:34 pm
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Back in the 30's and 40's dry ice and I think acetone was what was used. Liquid Nitrogen is probably safer and better. For indirectly heated cathodes I think high purity Mike of Magnesia is used.


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PostPosted: October 30th, 2022, 6:00 pm 
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Location: Parkville, Maryland
brombo wrote:
Back in the 30's and 40's dry ice and I think acetone was what was used. Liquid Nitrogen is probably safer and better. For indirectly heated cathodes I think high purity Mike of Magnesia is used.


Who is Mike Magnesia? :lol:

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PostPosted: October 30th, 2022, 6:21 pm 
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I can't spell. Milk of Magnesia.


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PostPosted: October 31st, 2022, 4:03 pm 
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More details -

https://hackaday.com/2018/12/31/the-art ... brication/


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