On Sat, 18 Oct 2014 09:24:33 +0200, Antonio I0JX wrote:

In the vacuum tube era, a tube (e.g. 6V6) was usually produced by
several manufacturers. I am not sure of how things actually went, but I
would say that a manufacturer initially designed the tube and put it on
the market, and subsequently other manufacturers "copied" the tube. But
how did they actually copy it? Just by reverse engineering (e.g.
measuring dimensions and distances among electrodes)? Or instead the
original manufacturer published the detailed tube design so allowing
others to produce it? The first option seems more likely to me, as
manufacturers should have little interest in helping others to replicate
a tube.

The same question applies to solid-state devices, but in that case I
would expect that reproducing a device having (almost) the same
characteristics through a reverse engineering process would be very
hard, if not impoossible.

Does any one know how things go in practice?

73

Tony I0JX Rome, Italy

While some copying may have happened, a lot of tubes weren't copied.
Look at a number of any of the common tubes, like 6SN7. There is a large
variety of internal construction.

And, as someone else mentioned, there was re-branding, where one company
made tubes with someone else's name on them. Every company did that,
both as a supplier and a buyer.

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Jim Mueller

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