Re: [TCML] Handmade Vacuum Tubes Video: Build A Better 811A Mousetrap?

["DC Cox" <resonance@xxxxxxxxxxxx>]

metal to glass seals are truly an art form and not for the inexperienced
experimenter.

Dr. Resonance

On Thu, Sep 11, 2008 at 9:32 PM, Brian Foley <ka1bbg@xxxxxxxxxxx> wrote:

> Hi, i often said the same thing "why cant we make our own" well, we can,
> but
> the equipment to do so would be a huge start-up nightmare......the hardest
> part of the tube work is de-gassing to temperature and the metal coatings
> is
> what makes a good tube....now i worked at a place that made RF amplfiers
> and
> also rebuilt power tubes, and one design of their own....now big tubes
> water
> cooled tubes to 500kw triodes....
> some of those tubes required renting a trailer mounted vacuum system, rf
> heating system, all kinds of heat control, glass, filiament, internal parts
> temps and seal temps......spent up to 3 weeks doing that pump down and
> de-gassing......event after the tube was taken apart, recoated/repaired,
> new
> filiament, etc
> done in a cleanroom.....then back filled with some exotic gas mixture..then
> load testing.....we can make dies and weld the parts together, its the
> clean
> room, chemistry, seal making, de-gassing and pump down that costs very big
> money.....a particle counter to tell what level of de-gassing the tube is
> at.......and after 4 weeks rebuilding the tube and have a filiament failure
> or a gassing problem, start all over again..that is the expensive
> part....or
> a failed seal, take it apart and start over......again....
> this man making tubes is definately a skilled glassworker, machinist, and a
> whole heap of equipment to make a tube and have it work.....also
> electronics
> savy as well....
> i would simply like to have a tube to display......surely a limited and
> very
> collectable tube...with the movie. cul brian f.
>
>
>      www.genapro.com
> ----- Original Message -----
> From: <Davetracer@xxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Thursday, September 11, 2008 9:13 PM
> Subject: Re: [TCML] Handmade Vacuum Tubes Video: Build A Better 811A
> Mousetrap?
>
>
> > You're right, that's an absolutely astonishing video! Making your own
> tubes
> > ... !
> >
> > And it makes me wonder...
> >
> >  ... What if we made a power triode with high power ratings for
> ourselves?
> > I'm actually not kidding after seeing that video.
> >
> > I know from direct vacuum tube experience that 811A-based Tesla Coils are
> a
> > great deal of fun.
> >
> > I'm a little concerned that the 811A's available now, especially from
> > Russia, suffer from quality control, because I've seen their plates go
> red
> far
> > faster than US-built equivalents, and I've seen plates melt unexpectedly
> quickly.
> >
> > But the French HAM radio operator in the video building his own tubes is
> > obviously running off qty 20 at a time. (You see him building inner parts
> 20 at
> > a time)
> >
> > If he can do that for tubes which are small and complex, and look
> something
> > like 12AU7's rough size (and please, I'm using the word "rough" here; I
> know
> > a 12AU7 is pretty complex), and he gets some use out of them in  his HAM
> rig
> > ... well ...
> >
> > Why can't we make some power triodes? Let me draw an analogy here on
>  what
> > they might be like.
> >
> > Do some early tries the Soviet Way: Bigger And Clunkier.
> >
> > Like this: Heck, when you started up the older model Soviet tanks, you
> > expected to gather a full kilogram of engine shavings in the engine oil
> during  its
> > first run, because the tolerances were so sloppy. You have to change that
> > oil before moving on.
> >
> > The 811A's were a design from the 1930's. (My old datasheet was copyright
> in
> > the 1930's). We don't have to match their "form factor" (their size and
> > shape). They have 4 pins -- 2 for filament, 1 for grid, 1 for plate.
> Filament is
> > 6.3 volts @ 4 amps. We don't have to match that, either. We can make
> > something far clunkier that isn't designed to have all the smooth
> characteristics of
> > a transmitter tube made for Class A, B, and C operations.  We're not
> going
> to
> > be broadcasting voice through this.
> >
> > What we need is something that will accept an input at the grid around 90
> > volts (100 V max) at 50 ma, max, to modulate a plate voltage of around
> 1200  to
> > 1500 volts max, switching on and off a current of 130 ma to 160 ma max.
> This
> > is around a 160 Watt tube (max).
> >
> > [A lot of the 811A specs are specifically for two-tube systems; pretty
> much
> > double the above figures, except plate voltage. Many 811A circuits are
> > push-pull and so forth.]
> >
> > There are also better metals and alloys than there were in the 1930's
> > (obviously).
> >
> > Most of the rest appears to be professional grade glassblowing, and I
> know
> > very little about that, so I'm smart enough to assemble the tube innards
> and
> > let  pros encase it in glass and evacuate it. (And possibly not glass if
> a
> > stronger  material would work.)
> >
> > My question for the List is this:  What characteristics of the 811A
> should
> > be improved upon? For example,maybe we should put a physically  stronger
> plate
> > in there that won't fail so quickly if it is heated to red. Do we  need
> more
> > current carrying capability? Then it needs a better anode and grid. I
> might
> > have to blow dust off the books, but vacuum tube design is very well
> documented.
> >
> > This might be really interesting.
> >
> > Thanks,
> >
> > Dave Small
> >
> > ******
> >
> >
> > In a message dated 9/9/2008 6:31:47 P.M. Mountain Daylight Time,
> > Sfxneon@xxxxxxx writes:
> >
> > If you  are really into hand building everything that goes into your in
> your
> >
> > VTTC, then how about making your own tubes like this guy:
> >
> > _
> http://blog.makezine.com/archive/2008/01/make_your_own_vaccum_tube.html_
> > (http://blog.makezine.com/archive/2008/01/make_your_own_vaccum_tube.html
> )
> >
> >
> >
> > (http://blog.makezine.com/archive/2008/01/make_your_own_vaccum_tube.html
> )
> >
> > Long, but well worth it!
> >
> >
> > Tony  Greer
> >
> >
> >
> >
> > **************Psssst...Have you heard the news? There's a new fashion
> blog,
> > plus the latest fall trends and hair styles at StyleList.com.
> > (http://www.stylelist.com/trends?ncid=aolsty00050000000014)
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
>
>
>
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