I wonder if there are archived anywhere some actual films of an old GE,
Mullard, Philco, RCA, Amperex, etc tube making process.
Some inside documentary or training film, that could be found and posted on
Youtube. I look back to the good old days, when I used to complain as a kid,
I paid $2.50 or so, retail for a 12AX7, after checking it in the tube tester
at the Longs Drug Store. Cosidering what went into making that precison
aligned; Two Plates, two grids, two filaments, or cathodes, all those exotic,
pure, and dissiilar metals, spot welds, 8-10 thru-glass pins, vacuum sealed,
getterized, and a couple or three businesses; manufacturer to retail, that
made a profit on that $2.50 retail tube. I am amazed.
They must have done big batch manufacture... say a run of I don't know 10,000
12AX7 plates 10,000 grids, etc..
Was there a much hand work involved in the miniature tube construction, or was
that highly automated, especially with aligning and spotwelding the various
electrodes? They did not have robotic welders, etc back then.
Same for the big TX tubes....anyone have any idea what the alignment tolerances
were/are between fil to grid, and grid to plate?
or grid to grid for some tubes?
The other thing that is astonishing, I have an 833A AM Broadcast TX tube, one
of a pair of pulls, I think used to be good for a KW AM, along with an
identical pair of modulators, and the Plates ran bright orange, particularly
the modulators.
The tube envelope has a BIG embedded air bubble in the glass envelope, that
you can see was elongated in the envelope manufacturing process. you can kind
of see a pulled shape of the bubble, when the molten glass flowed I am amazed
that the tube survived that big, apparently weak spot at the air bubble....
Best Regards,
73, de Pat Barthelow AA6EG
> From: km1h@jeremy.mv.com
> To: tonne@comcast.net; amps@contesting.com
> Date: Mon, 30 Aug 2010 09:04:50 -0400
> Subject: Re: [Amps] Why do tubes cost so much?
>
> I read somewhere (years ago so dont quote me) that tubes with extremely
> close grids such as the 3CX800 and 1500 have yields around 20%. You would
> think that after all these years companies would have better technology
> available to assemble.
>
> Setup times should be controlled also, I just suspect that Eimac doesnt care
> since they still have the bulk of the market that will pay whatever it
> costs.
>
> Carl
> KM1H
>
>
> ----- Original Message -----
> From: "Jim Tonne" <tonne@comcast.net>
> To: "Frederick Mott" <fredmott@zoominternet.net>; <dezrat1242@yahoo.com>;
> <amps@contesting.com>
> Sent: Sunday, August 29, 2010 9:40 PM
> Subject: Re: [Amps] Why do tubes cost so much?
>
>
> >
> > I think that Bill and Fred have summarized things
> > nicely.
> >
> > But I also suspect that the "tiny" tubes like a 6BA6
> > are assembled in a relatively (if not entirely) automated
> > operation. And I chose the 6BA6 because of how the
> > first grid is formed, with that nonuniform winding.
> >
> > The "big" tubes - those with 100 kW or more of plate
> > dissipation - offer the same challenges that the 1000
> > watt tubes do but are simply scaled up and are
> > larger in every respect and so probably relatively
> > easier to build. The cost of materials in those huge
> > tubes is probably significant. So is warranty cost.
> >
> > - JimT W4ENE
> >
> >
> >> I have often wondered why big tubes cost so much.
> >
> >
> >
> >
> >
> > _______________________________________________
> > Amps mailing list
> > Amps@contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
>
> _______________________________________________
> Amps mailing list
> Amps@contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|