Re: vacuum tube construction. (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Sun, 12 Aug 2007 17:32:10 -0700
From: Ed Phillips <evp@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: vacuum tube construction. (fwd)

Tesla list wrote:

>---------- Forwarded message ----------
>Date: Sun, 12 Aug 2007 17:02:40 -0400
>From: Scott Bogard <teslas-intern@xxxxxxxxxxx>
>To: tesla@xxxxxxxxxx
>Subject: vacuum tube construction.
>
>Hey guys.
>     We build all sorts of things for our coils, capacitors, hand wound 
>transformers, all kinds of ballasts, Has anybody tried to build a vacuum 
>tube for a tube coil?  It sounds slightly crazy, but several of us, with 
>varying degrees of success have built plasma globes, Geisler tubes, etc, 
>which require a vacuum (although they are generally backfilled some with 
>noble gases).  If you were building it yourself, you could make it rather 
>large, to drive a rather big VTTC.  Just curious.
>Scott Bogard.
>
    The construction of a power tube is not a matter for the home unless 
one has an unusual lab.  First of all requires very high vacuum.  Beyond 
that it requires special "cross-fires" [burners}fed with oxygen,  
equipment to handle hard glass, a special glass lathe to join the 
electrode assembly to the main envelope, proper anode, grid and cathode 
materials, a bakeout oven to anneal the tube after assembly and to 
maintain it at temperature during continued pumpint while the electrodes 
are heated with an induction heater until the asembly is "out gassed", 
and finally a design for the tube and some means of shaping the 
electrodes.  I can't say that no one has built such a tube "at home" but 
doubt it very seriously.  A big job even for professionals and requires 
all sorts of skills.

    By contrast, soft discharge tubes are literally child's play.

Ed