• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Build Your Own Vacuum Tubes

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Kevin - Yes. The forum was set up by Trevor, an early attendee to the Vacuum Tube Workshop. He has really gotten into the hobby of DIY tubes and decide to start a forum where others that are interested in the hobby could come and exchange ideas and techniques. He's gone as far as to start building a tube lab in his apartment. I hope the apt. manager doesn't find out. He's already built a glass lathe from scratch and is now working on his vacuum system.

Anyone interested in watching and/or doing projects in this lost outpost of science is welcome to come and visit.
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Cool, I've always been fascinated by the idea of making diy vacuum tubes, it melds a lot of skills from very diverse disciplines.

I'll keep my fingers crossed on the apartment thing, my various old landlords looked the other way because I was handy and could fix things around the building that others couldn't. I wasn't attempting to make vacuum tubes of course.

My wife has stated she would have no problem with me making vacuum tubes in the basement as long as I didn't burn the house down.. lol

I possess rudimentary machining skills so I think will be a long time (if ever) before I reach the point of being good enough in all of the required disciplines. Glass blowing which I have seen live scares me..
Kevin - Rudimentary skills and common tools are all that are needed to get started making DIY tubes. The only possibly esoteric parts might be the vacuum pump and gauge. A good 2 stage mechanical pump and a vacuum gauge will allow you to make interesting tubes. The glass lathe can be avoided if you use low vapor pressure epoxy to seal the tubes. No glass blowing is needed for entry level tube building. All of this is covered on Trevor's site. It can be done!

Aleksander - I checked out your website. Very impressive! You should come over and visit Trevor's site. I'm sure that you could provide a lot of good information that others would enjoy hearing about. If we all share, we all gain.
SY - A good 2 stage mechanical pump with clean oil in it can easily get below 10 microns (mTorr). Most of the receiving type tubes made on Sealex machines are only pumped down to pressures of a few mTorr. Here's a quote from Bachman's excellent book Experimental Electronics: "In the manufacture of many radio tubes it is standard practice to seal the tubes off at comparatively poor vacua - well above a micron - and depend upon getter action to reduce the tube pressure to values often better than 10^-5 mm Hg". This fact is not generally known outside of the tube making industry. Larger tubes are often pumped and baked on stationary manifolds which are pumped by diffusion pumps or other high vacuum pumps. The larger typical output tubes require a much higher level of processing than small receiving and amplifier tubes.

What this means is that useful small signal vacuum tubes can be made by the hobbyist with just a good mechanical pump and getter.
Mr_Z - Thank you for the post recommending John Strong's books. His work is classic in the realm of science hacking. Good books are as important as good tools when doing experimental science.

rmyauck - The simple answer is no. You'll want a rotary type pump for making vacuum tubes. A 'V' pump would indicate that this is a reciprocating piston type pump. Also, 'big' is sort of meaningless when pumping on small signal tubes.
Sorry George about just just typing a V for short, as I meant Vacuum pump. According to Robinair (the manufacture), " two-stage, offset, rotary vane design provides powerful, quiet,
high vacuum capability."

I used to work with XRF (used a high vacuum chamber where sample was blasted with x-rays and sensors picked up % of element maybe present) machines and they used a vacuum pump which might be the right type of pump as they were designed to hold a vacuum for many hrs.

Thanks very much!

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Randy - OK, now my answer is yes, provisionally. A new or well maintained 2 stage Robinair pump with clean oil in it should be able to get you down to some pressure below 10 microns. I can't over state the necessity of having a good, calibrated, vacuum gauge in any vacuum system that will be used to make DIY tubes.
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