>rich wrote,
>
>> - However, by temporarily introducing acetylene gas (C-two, H-two) into
>> the envelope, the tungsten carbide layer can be restored to full emissive
>> capability.
>
>neat! i didn't know that (amongst billions of other things). but it
>seems slightly beyond the capabilities of the average ham. i mean
>even the average amplifier builder, who is *way above* the average
>ham in technical capabilities! i wonder if it's cost effective for
>any tubes other than big-ticket jobs (with handles!) i can't imagine
>reconditioning 3-500's for instance.
As I understand it, the smallest tube being recarburized by Econco
(916-662-4495) is the 3CX1000A7.
- RE: Technical capabilities: Some hams appear to have remarkable
capabilities, George. For instance, W8JI, Tom Rauch, recently disclosed
that he built triodes from 3CX15,000 parts. Econco appears to have
similar capabilities. The assembly/disassembly process is really not all
that exotic since the ceramic insulators are simply silver-soldered to
the anode, grid, and filament collets.
>
>i've got some meters and oscilloscopes and a radial saw, but i can't
>imagine trying to bring a tube back to life this way! maybe rich
>should have added..."don't try this at home." 8>) (that's a grin)
>
The basic process:
1. The envelope is supplied with a constant flow of acetylene gas.
2. The filament is energized and the current measured with a digital
voltmeter. .
3. The atoms of carbon in the acetylene molecules combine with tungsten
on the surface of the filament, leaving hydrogen atoms, which are flushed
out in the flow of acetylene.
4. Since di-tungsten-carbide is less conductive than tungsten, the
thickness of the carbide layer can be gauged by measuring the decrease
in filament current.
5. When the current decreases enough, the carbide layer is the right
thickness,, the acetylene is removed, and the vacuum re-pumped.
-Rich---
R. L. Measures, 805-386-3734, AG6K
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