Where to find germanium transistors

Included is a 19 page mini manual which contains: Schematics, hook up information, frequency charts, gain-frequency charts, illustrated suggestions for various input and output circuits and applications with schematics, plus bias considerations.

These are the perfect building blocks for Microphone pre-amplifiers such as used inside of Condensor Microphones or to craft a dual chanel Hi-End Mic Pre-Amp for field recording applications to be used with modern recording equipment.

It is rare to find these modules at all - and it is extremely rare to find 2 equal units in unused condition. This is a once in a lifetime single item opportunity and once sold it is gone - forever. Dimensions: aprox. These tubes are used but test as strong as new ones. As these came out a vintage piece of equipment they are dusty on one side. Tubes will be tested individually with my Hickok Transconductance tester before shipping.

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Pages: [ 1 ] Go Down. Germanium transistors Discussions of tubes, transformers, capacitors, and other discrete parts of radios, radio restoration and repair services. Ads are not permitted. I need the specs on them so I can maybe find matching replacements.

I have looked all over the internet and no luck at all. These transistors are in a TO7 package. Any of you have experience with these transistors? TO7 and TO45 are the same case.

TO45 is what replacement transistors were made to. It's also what most distributors will sell you. SK transistors are still around, albeit scarce.

EDIT: Added picture. These transistors "do not work". When I put them in the 1'st IF, they go into oscillation big time. As far as I'm concerned these transistors are junk. I did a complete cap replacement and it worked great, until I accidentally shorted out the 1'st IF with my soldering iron. So now I have no XB's to replace it with. There must be data somewhere, I would think. These developments could be the first steps in an industry trend to adopt the use of higher and higher proportions of germanium in the channel.

Germanium was first isolated and identified by the German chemist Clemens Winkler in the late 19th century. Solid-state devices based on germanium boomed in the postwar years; U. But silicon ultimately won out; it became the material of choice for logic and memory chips. There are some good reasons why silicon dominated.

For one thing, silicon is far more abundant and thus a lot cheaper. Silicon also has a wider bandgap, the energy hurdle that must be overcome in order for a transistor to carry current. The answer is mobility. Electrons move nearly three times as readily in germanium as they do in silicon when these materials are close to room temperature. And holes—the electron voids in a material that are treated like positive charges—move about four times as easily.

Speedy Circuits: This nine-stage CMOS ring oscillator, presented in , was built on a germanium-on-insulator wafer. The fact that both electrons and holes are so mobile in germanium makes the material a convenient candidate for constructing CMOS circuits. The faster these electrons and holes can move, the faster the resulting circuits can be.

And because less voltage must be applied to draw those charge carriers along, circuits can also consume considerably less energy. The III-V compounds mentioned earlier, materials such as indium arsenide and gallium arsenide, also boast excellent electron mobility.

In fact, electrons in indium arsenide are nearly 30 times as mobile as they are in silicon. So far, so good. The problem is that this amazing property does not extend to the holes in indium arsenide, which are not much more mobile than holes in silicon.

One potential fix is to take the best of each material. This technique could lead to very fast circuits, but it also complicates the manufacturing process. For this and other reasons, we favor a straight-germanium approach.

The germanium channels should significantly boost performance, and the manufacturing challenges are expected to be more manageable. Fortunately, there are multiple ways to build a germanium layer on a silicon wafer that can then be fashioned into channels.

Using a thin layer of the stuff significantly mitigates two key problems with germanium—the fact that the material is costlier than silicon, and that it is a relatively poor conductor of heat.

The channel has to work seamlessly with the other components of the transistor. It has four basic parts. There are the source and drain, which are the origin and destination point for the current; the channel that connects them; and the gate, which is essentially a valve that controls whether current flows through the channel.

In reality, there are several other ingredients inside a state-of-the-art transistor. One of the most critical is the gate insulator, which prevents the gate and channel from short-circuiting. The atoms in semiconductors such as silicon, germanium, and III-V compounds like gallium arsenide are arranged in three dimensions. There is no way to create a perfectly flat surface, so the atoms that sit on the top of the channel will have a few dangling bonds.

So what you want is an insulating layer that links up with as many of those dangling bonds as possible, a process called passivation. Because silicon and SiO 2 are close structurally, a well-made layer of SiO 2 can bind to 99, of every , dangling bonds, which is about how many there are in each square centimeter of silicon.

Gallium arsenide and other III-V materials do not have native oxides, but germanium does, which means it should, in theory, have an ideal material to passivate a germanium transistor channel. The problem is that germanium dioxide GeO 2 is weaker than SiO 2 , and it can absorb or even be dissolved by the water used to clean wafers during the chip manufacturing process.

To make matters worse, it is hard to control the GeO 2 growing process. Researchers have studied some alternatives. But germanium passivation took a big step forward in , when a team led by Professor Shinichi Takagi of the University of Tokyo demonstrated a way to control the growth of germanium insulator.

The researchers first grew a nanometer-thick layer of another high-k insulator, aluminum oxide, on the germanium channel. Once this layer was grown, the ensemble was placed in an oxygen-filled chamber. A fraction of that oxygen passed through the aluminum oxide layer to the underlying germanium, mixing with the germanium to form a thin layer of oxide a pairing of germanium and oxygen but technically not GeO 2.

In addition to helping control the growth process, the aluminum oxide acts as a protective cap for this weaker, less stable layer. Bridge to Higher Performance: Chipmakers may one day turn to nanowire channels, like these germanium structures.

Nanowires can be surrounded by a gate on all sides for added control. S everal years ago, inspired by this finding, and facing the difficulties involved in creating pFETs with III-V channels, my group at Purdue began investigating ways to build germanium-channel transistors. We began by using germanium-on-insulator wafers, developed by the French wafer manufacturer Soitec.

These wafers are standard silicon wafers topped with an electrically insulating layer underneath a nm-thick layer of germanium.