Fifty years ago this month, QST carried an article entitled “Vacuum Tubes The Hard Way.” The author was Sam Diaz Pumara, ex-LU2DII. The Argentine ham’s address was listed as being in care of HRB-Singer, Inc., of State College, Pennsylvania, which is now part of Raytheon. Diaz details the meticulous process for building vacuum tubes in his basement. The end result is some of the samples shown here.

Making a vacuum tube at home is not a trivial proposition, but it is within the capabilities of an experienced craftsman. The first problem is creating a sufficient vacuum, which the author accomplished by using a variety of oil pumps, the last of which produced a vacuum of 10^-8 Millimeters (presumably meaning a column of mercury of that height). But the vacuum wouldn’t last, since the elements of the tube (and the glass itself) would occlude gasses. This problem was solved by heating the tube during the evacuation process to a temperature of 500 degrees centigrade.

The actual construction of the internal elements of the tube is a simpler proposition, but the painstaking detail needed in this work is also described in detail.

Another interesting article on the construction of homemade tubes can be found at the website of Dr. Rüdiger Walz. He mentions some of the other experimenters in this field, including Diaz.  One of the experimenters in this field had a call similar to my own, Marold Ross, W6IS, of Baldwin Park, California.

Finally, the video below shows Claude Paillard, F2FO making tubes:

You can view the 1965 article at this link.  (You need to be logged in to your ARRL account to download the QST article.)  For a much simpler method of making a diode vacuum tube, see my earlier post.

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