Don't know of any US but try this
http://www.youtube.com/watch?v=VV7cimRWah0
and
http://www.youtube.com/watch?v=HveUY7eivfI&feature=related
both are multipart
On Mon, Aug 30, 2010 at 7:20 AM, Patrick Barthelow <apolloeme@live.com> wrote:
>
> 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.
>> >
>> >
>> >
>> >
>> >
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>>
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