China Grand Tour 2009
Shuguang Vacuum Tube Factory
Report By Steven R. Rochlin
Step right up here
folks and watch how Shuguang makes a 300B triode output tube! The factory can make 60 regular
or 30 of the Treasure Series per day. Only four employees have top level skills to make the Treasure
Series tubes.
Inspecting the assembly.
Attaching outer carbon-coated plate element.
One both plates are installed, they carefully solder the plate pieces together.
As for small signal tubes and how they get
their sey nipple top, if you remember yesterday's factory tour you'll recall that
a 'drink straw' glass tube that is used to aid in forming the vacuum. Well, here
is how they removing the top 'drink straw' of a small signal tube.
At the top of these tubes is aluminum and barium. Have you ever wondered how they get that silver-colored top on the
inside of the glass?
So they heat just the top of the tube through extremely high voltage 400 degrees Celsius electric/magnetic field and this causes the top silver coating to form on the
tube's glass surface. Did i mention this is extremely high
voltage and i had to get very close to capture this photograph? They asked me to be
very careful getting the above photos due to the obvious danger involved.
Below is the after and before product.
If the tube goes bad, this silver coating turns
white as seen above.
Box of gold pin tubes.
So where does Shuguang get their gold and
silver plated wire. They make it themselves! As you can see above, the right spool is silver colored and as it goes through a brief
process where gold evenly
forms on the wire and it is gathered on the left spool.
Gold-plated wire anyone? The wire is made of molybdenum and then it goes through a process where a
10µm coating is formed on the wire. The factory uses 20 grams of gold per day to make this
wire (a troy ounce of gold is 32.15 grams). Two grams of gold
makes approximately 1000 meters of wire. So why gold or silver coated wire you ask? For heat dissipation mainly and of course to reduce corrosion and ensure
uniformity.
The gold wire is wrapped around copper posts to
make the grid.
Here they are shaping a silver plated wire grid and one operator makes 3000 of these per day.
Coating of the cathode.
Hair-thin Tungsten wire coated with aluminum
oxide is being prepared for a very special coating process.
After this coating the wire is heated to 1700 Celsius, the aluminum oxide becomes hard like
ceramic.
Many tubes go through an eight hour burn in
process on the racks. This room had at least, well... i lost count yet must be 1000+ tubes going at a
time on many rows of racks (only one of the many are pictured here).
Shuguang is a very large facility and it almost
boggles the mind how many tubes that can manufacture each day. Was impressed
how efficient and fast everyone was able to get their task completed as tubes
went through each step of the manufacturing process. This is one of those
once-in-a-lifetime tours that i'll always happily remember when i use Shuguang
tubes in my equipment.
Website: www.shuguangelec.com
Click here for the main China
2009 tour page.
