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Tokin SIT DEFiSIT musings
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Old 7th February 2020, 06:59 PM   #61
Nelson Pass is offline Nelson Pass  United States
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Tokin SIT DEFiSIT musings
The 2SK60/2SJ18 are nice devices. I own a small inventory of them as
well as 2SK82/2SJ28 and numerous other SITs.

Their junctions are not insulated and will conduct current if forward
biased and the curves show the characteristic Id dependence on Vds as
do all SITs. Apart from sheer die size, I don't see any remarkable
differences.

I happen to have a nice set of curves for all my SITs operated as
single-ended followers under very similar conditions, and what I see is
reasonably similar results for the Sony parts and the 2SK182's and
THF51s.

The Sony parts come in about .2% thd at 1 watt 8 ohms, and 1% at 10
watts. The bigger parts come in around half that, and can be operated
to 50+ watts. Both these numbers are consistent with die size, and
of course the capacitance is higher, requiring a lower source impedance.
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Old 7th February 2020, 09:00 PM   #62
N101N is offline N101N
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Right.

JFETs have a cloudy gate-channel diode, whereas MOSFETs an equally cloudy insulated capacitive gate. The 2SK60 is neither a MOSFET nor a JFET, different from everything else. It does not have a P-N junction, but a low distortion, low impedance interface.
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Old 7th February 2020, 10:31 PM   #63
woofertester is offline woofertester  United States
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Quote:
Originally Posted by N101N View Post
woofertester,
transistors conceived to work as a switch feature huge interelectrode capacitances, low conduction channel resistance, low switch-off voltage, high input impedance, high doping levels, a thin dielectric layer contaminated with toxic heavy metals and inexorably exhibit high signal distortion.

The 2SK60 is one of only a few power transistors that was explicitly developed with the intention of designing an audio amplifier by employing uniquely peculiar, advanced techniques. What do you think your measurements could reveal?
The measurements should either prove or disprove your assertion that "the 2SK160 and 2SK182 have nothing whatsoever in common".

Nelson's latest post leads me to conclude that the 2SK182 is a good part to use in one of his amplifier SIT designs.

I just used a pair of bench multimeters to take a diode measurement of a 2SK160 and a 2SK182. The diode function of this DMM forces 1mA and measures voltage. I used the second DMM to measure the current of the first DMM that is taking the diode measurement.

The 2SK160 has a 0.7V drop from gate to source at 1mA
The 2SK160 has a 0.7V drop from gate to drain at 1mA

The 2SK182 has a 0.61V drop from gate to source at 1mA
The 2SK182 has a 0.61V drop from gate to drain at 1mA

The family of curves for the 2SK182 look triode-ish in the same way that the 2SK160 looks triode-ish.

The only thing remaining is to measure the CV curves which requires a lot of setup which I can do at some point.

Nelson has already contributed the objective amplifier distortion measurement results. It makes me glad that I snagged some 2SK182 devices.

It would be instructive to have an A/B critical listening test of a 2SK160 amplifier against a 2SK182 amplifier using the same topology with the same front end. I don't qualify for the critical listening judge position. I do not have the thousands of hours of critical listening training.

Last edited by woofertester; 7th February 2020 at 10:34 PM.
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Old 8th February 2020, 01:16 AM   #64
N101N is offline N101N
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Quote:
"the 2SK160 and 2SK182 have nothing whatsoever in common".
Aside from the misleading name. SIT is just a principle that was announced back in 1950. The 2SK60 is Sony`s impressively successful implementation of the principle.

Remember that the 2SK60 is more problematic to deal with and much less powerful than the 2SK182.
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Old 14th February 2020, 07:16 AM   #65
N101N is offline N101N
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Some essential aspects are missing from the discussions.
The gate to channel boundary is a principal source of distortion. This is where the dedicated SIT technique shines. The technique requires a vertical structure, JFETs have a lateral structure.
Also the Yamaha devices are respectable family members, the Tokin devices and the silicon carbide JFETs are not.
All that worthless mathematical gibberish does not provide any knowledge.
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Old 14th February 2020, 07:53 AM   #66
Zen Mod is offline Zen Mod  Serbia
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Tokin SIT DEFiSIT musings
facts are facts , some parts are more linear and predictive/uniform in transfer characteristic , some are less

though , it's all matter of availability - when having fun , one can't be too choosy if parts are scarce and better to use what you can than craving for unobtanium

in any case , whatever you have to share about technology etc. , do not hesitate to share ......... it could lead to better implementation of whichever parts we can get
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Old 14th February 2020, 06:18 PM   #67
woofertester is offline woofertester  United States
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Do you have any measurements to back up your claim that the Tokin devices and Silicon Carbide devices are not as good as the 2SK60? Nelson has graciously posted his findings comparing the Sony SITs to the Tokin SITs. He has measured more distortion in Sony SITs for the same circuit and operating conditions.


Quote:
Originally Posted by N101N View Post
Some essential aspects are missing from the discussions.
The gate to channel boundary is a principal source of distortion. This is where the dedicated SIT technique shines. The technique requires a vertical structure, JFETs have a lateral structure.
Also the Yamaha devices are respectable family members, the Tokin devices and the silicon carbide JFETs are not.
All that worthless mathematical gibberish does not provide any knowledge.
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Old Today, 04:07 AM   #68
N101N is offline N101N
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Zen Mod,
Obtainability is a tangible aspect, factuality is much more elusive and sometimes undesirable.

woofertester,
You deceive yourself by believing in the kind of "proof" you are asking for. Static device properties allow making certain intuitive performance estimates based on the relationships between electrical quantities. Again, a high reverse transfer capacitance, low conduction channel resistance and high transconductance cannot entail low distortion regardless of what measurements imply. It is just not physically viable. Low distortion comes at the expense of power handling capability.

Nomenclature in physics is generally perplexing. Don't wonder why the nonsensical name Static Induction Transistor has been assigned to entirely different types of transistors.
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Old Today, 04:26 AM   #69
woofertester is offline woofertester  United States
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One of my favorite sayings is from Sir William Thompson a.k.a. Lord Kelvin

...when you can measure what you are speaking about, and express it in numbers, you know something about it; but when you cannot measure it, when you cannot express it in numbers, your knowledge is of a meager and unsatisfactory kind; it may be the beginning of knowledge, but you have scarcely in your thoughts advanced to the state of Science, whatever the matter may be...

Two more

"To measure is to know."

"If you can not measure it, you can not improve it."

One reason I follow this forum is that Nelson measures and listens to his designs and has other knowledgeable listeners evaluate his designs.

I will enjoy very much building and listening to his upcoming SIT designs.

cheers





Quote:
Originally Posted by N101N View Post
Zen Mod,
Obtainability is a tangible aspect, factuality is much more elusive and sometimes undesirable.

woofertester,
You deceive yourself by believing in the kind of "proof" you are asking for. Static device properties allow making certain intuitive performance estimates based on the relationships between electrical quantities. Again, a high reverse transfer capacitance, low conduction channel resistance and high transconductance cannot entail low distortion regardless of what measurements imply. It is just not physically viable. Low distortion comes at the expense of power handling capability.

Nomenclature in physics is generally perplexing. Don't wonder why the nonsensical name Static Induction Transistor has been assigned to entirely different types of transistors.
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