SIT Power Amplifier???

[mad_z]

Hi everyone!!!

there is the japanesse page with many designs, among them there is sth called SIT amplifier - where can I find some info about that???...in english of course

I tried translating with altavista, but effects are not good...

the site:

http://www.ne.jp/asahi/evo/amp/SITamp.htm

thanks.

[JohnG]

Try searching Google for "static induction transistor". It's been a while, but this is something akin to a power JFET, or maybe a power MESFET (not MOSFET!).

John

[dimitri]

From:
http://www.rsc.rockwell.com/html/electronics.html
For much higher levels of output power, we have two distinct technologies that cover complementary frequency ranges, both based on wide bandgap semiconductors. These have inherent advantages over conventional semiconductors in terms of higher temperature of operation and higher breakdown voltage. A SiC based MESFET (metal semiconductor field effect transistor) and SIT (static induction transistor) have been developed for use in X-band and L-band, respectively. These offer several exciting application options including a myriad of military communication bands at L-band and below, as well as future cellular phone base station amplifiers. For higher frequencies, we are developing a GaN based HEMT technology that has demonstrated high power performance at X-band and above.

The new tokin sites:

http://www.iijnet.or.jp/EMCE/index-e.htm
http://www.nec-tokin.com/

Translation from:
http://www.ne.jp/asahi/evo/amp/SIT/page1.htm
http://www.ne.jp/asahi/evo/amp/SIT/page2.htm
The SIT because it is the element of 3 polar vacuum tube type qualities whose resistance inside the drain is low, when it uses for the output step of the power amplifier, not depending on the NFB, you can obtain low output impedance. The on that, it meaning that input resistance does not require power for drive high, it can construct the power amplifier in quite the simple circuit.
The SIT was proposed in 1950 by Professor and others Tohoku University Nishizawa. The usual connecting type field-effect transistor (the JFET), controlling the electric current which flows to the channel, due to the depletion layer you obtain transistor quality, but because the channel is long, channel resistance (source resistance) becomes high, on resistance large, operational speed slow. In addition electric current is saturated by the negative feedback effect to which drain voltage operates the depletion layer. Then, when the channel is made short, channel resistance is made to decrease to the extremity, the negative feedback effect does not occur, electric current is not saturated can obtain " 3 polar vacuum tube type qualities ". This effect with the electrostatic induction effect, the electrostatic induction type transistor (the Static Induction Transistor SIT) with is the transistor which utilizes this. The SIT and so on is warped loss and high-speed operation, low and low has feature.

[JonMarsh]

SIT Fets were used in the output stage of the Yamaha B1 amplifier, back in the mid 70's. Depletion mode devices like these are harder to interface with and drive, as solid state devices go, but then there weren't any conventinal vertical DMOS transistors at this time (Siliconix VMOS and IR and Siemens DMOS were a few years away from commercial release), so this was pretty innovative for it's time. Making the transistors, particularly the buried gates, is pretty tough, especially with consistency.

-Jon

[jcarr]

New link of SIT amp:

http://www.ne.jp/asahi/evo/amp/CSPP/2SJ18.htm

Sony's SJ18 devices have been out of production for many, many years, so you would have to be very lucky to make use of the information on this page.

Interesting nonetheless...

regards, jonathan carr

[mad_z]

Thank for feedback!

It seems that not many projects there are on the net using SIT transistors...

There is another page:
http://www.mobara.ne.jp/~yamada/sit/index.html

in japaneese of course

[nl]

I listened to SIT-based amps while in Tokyo a couple years ago. Quite promising. The Tokin SIT is apparently available from Hino Audio. Look at this link for more info.

http://www.ne.jp/asahi/evo/amp/SIT/page1.htm

It is quite expensive, quoted at 60,000 yen for a set of four. Note that, due to its ability to swing large voltages (450V), and limited current output (4A peak, about 400mA idle common), it is normally used with an output transformer! Indeed, Plitron makes a toroidal solid-state OPT that would fit this unit nicely.

[tube-lover]

hi,

how about the sound quality of this sit amp????


thx


thomas

[frankln]

Originally posted by jcarr
New link of SIT amp:

http://www.ne.jp/asahi/evo/amp/CSPP/2SJ18.htm

Sony's SJ18 devices have been out of production for many, many years, so you would have to be very lucky to make use of the information on this page.

Interesting nonetheless...

regards, jonathan carr

do you know how to adjust VR1, VR2 & VR3?