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Old 12th October 2004, 04:40 PM   #231
PMA is offline PMA  Europe
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Be careful, you are going to dissipate 94W on every of the MOSFETs ....

You might like to start with 8R resistors.
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Old 12th October 2004, 07:10 PM   #232
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Default fan cooling?

If i use a small fan for cooling... can I get away with 1 mosfet per channel??

Thanks!!
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Old 12th October 2004, 07:19 PM   #233
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You will have to know thermal resistance of the transistor (depends on package and chip), insulating pad and heatsink. Take into account that 1C/W of the summarized thermal resistance will cause 100C increase of chip temperature (provided there is a 100W power dissipation).
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Old 23rd October 2005, 04:16 PM   #234
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Quote:
Originally posted by janneman


The 2SK60 and it's complementary device 2SJ18 are both enhancement types which were used by Sony in for instance their TA-N7 in the late 70's.

They were used as cascodes for the output stage, which had low-voltage bipolars driving the load.
Jan Didden
Why not the other way round ? Bipolar as cascode for the V-fet ?
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Old 23rd October 2005, 07:28 PM   #235
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First, because the bipolar has a higher Gm, which makes some things easyer, and second, because the VFET, unlike the bipolar, does not have a secondary breakdown problem - so you want to keep the voltage across the bipolar relatively low.
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Old 23rd October 2005, 08:38 PM   #236
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OK,

but wasn't the Vfet originally used (in the earlier amps ) for high speed, good linearity and because it is a voltage controlled device ?
But in the TA-N7 ( which I own ) the gain device is bibolar, is this still a Vfet amp ?
Any sense to built a single ended classA amp with N-Vfet and bipolar or mosfet current source ?
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Old 30th June 2009, 01:36 PM   #237
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Hello,
today the 2SK70 and 2SJ20 V-Fet In this form, what alternatives might be?
hard to find.

best regards. Can.
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Old 4th December 2009, 03:33 PM   #238
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Can someone share a circuit design using single ended 2SK60 or 2SJ18?

Would be nice to mate it with a DHT preamp
(something like the circuit shown in the #23 thread)
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