
Sylvania Factory Tour – Vintage Tube Services - wglb
http://vintagetubeservices.com/sylvania-factory-tour/
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kw71
Thermionic tubes are works of art. It's amazing that most of the work to build
these was done by hand, and yet they perform very well and are highly durable.

Now the article has me wondering what a DC Millimeter is. :) I think I need to
get one for my metrology stack.

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dietrichepp
"Most of the work was done by hand..." Well, the machines and jigs to make
them were quite sophisticated.

From the video:

"You'll notice that at no time are they touched by hand." Start at about
12:05:

[https://www.youtube.com/watch?v=GDvF89Bh27Y&t=12m05s](https://www.youtube.com/watch?v=GDvF89Bh27Y&t=12m05s)

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nitrogen
Does that video cover blowing the glass?

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kazinator
_> "This tube crushing machine prevented any seconds from falling into
dishonest hands!"_

How ironic! Little did they suspect that people would be trading completely
fake Sylvania (and other) "new old stock" tubes decades later.

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kw71
I have come across lots of jerks selling bad old tubes ("but my tester
featuring unknown principles of operation pointed the needle at the GOOD
sector, not the BAD or "?" sectors!" (What kind of instrument has a "?" on the
meter face?))

I wonder how the counterfeits would be done today, since the phenolic bases on
the old octal tubes probably can't be matched by any material around now.

~~~
dietrichepp
> What kind of instrument has a "?" on the meter face?

I've seen a few equipment testers with a "?" between "Bad" and "Good". I have
a battery tester with this, and tube testers like this are not uncommon. They
are typically emission testers, which wire up the tube like a diode, with the
grid wired to the cathode. As the tube ages, the cathode coating will wear out
and emission will drop. The cathode coating wears out through normal use the
same way an incandescent lamp wears out: at normal temperatures, it will
evaporate and get deposited somewhere else in the tube. Emission testing is
far from perfect, but it's a good first test to figure out e.g. which tube is
a dud.

I have a hard time caring because I never buy NOS tubes (same reason I don't
buy CA3280s).

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kw71
A friend of mine has an emission tester (maybe it can put some signal on the
grid - I haven't seen it in a while.) I've got a hickok machine that you look
up the grid bias in the chart and can receive a reading in ... micromhos? Ok
that implies conductance but that's a strange unit. I'm not sure these are
"instruments."

My treasure is a machine from soviet russia, it actually uses a signal
generator to feed the grid, and measures transconductance in mA/V. It's got a
bunch of power supplies, VTVM and microampere meter whose smallest scale
resolves some nanoamperes, so I trust its methodology. It's nice to find the
actual current passed by a rectifier tube instead of setting a meter bias knob
to read out the 'strength' on a unitless 0-100 scale.

But I never figured out how to intereperet the "?" on the emission testers.

My tube fap shrine won't be complete until I get a Tek 575 though.

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dietrichepp
I'm not sure why the mho is a strange unit. It is just another name for the
siemens (a.k.a. ampere per volt).

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Aloha
While this is cool, the rest of the website is made of snake oil.

