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Old 11th November 2011, 01:36 PM   #41
sureshm is offline sureshm  Australia
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Are the 500V Cornell Dubilier 380LX any good for the Simple SE? They are 85C so wondering if they are reliable?
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Old 11th November 2011, 01:50 PM   #42
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Are the 500V Cornell Dubilier 380LX any good for the Simple SE?I bought some and stuffed them in an SSE board. They seem to work OK but I haven't used the amp enough to judge reliability. I would guess that they will be OK if you mount the caps on the back of the board to avoid radiant heat from the output tubes.

Newark (Farnell) now has some 105C rated Nichicons. I just got 10 of them but haven't tested them yet.
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Old 11th November 2011, 03:50 PM   #43
rknize is offline rknize  United States
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Also, the area around the rectifier runs a little hotter on the TSE than the SSE, due to some additional power resistors (particularly R6).
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Old 3rd January 2012, 07:30 PM   #44
jrenkin is offline jrenkin  United States
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Quote:
Originally Posted by boywonder View Post
A related question for mostly educational reasons.......In a Tubelab SE (or similar source follower application) if the rectified off load voltage of the transformer is greater than 500V, is that a problem for 500V rated parts such as the 2SK3563?

Any thoughts on this?
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Old 3rd January 2012, 07:43 PM   #45
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Default What he said........

If I had to re-phrase the question today....

If the mosfet drain-source voltage rating is 500V, what prevents that spec from being exceeded (especially at startup) in the circuit? It seems that with 300B's the source voltage is as negative as -300 volts or more, not considering the + voltage on the drain.

Still wondering myself.........
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Old 3rd January 2012, 08:10 PM   #46
rknize is offline rknize  United States
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The MOSFET will never see that. The gate is derived from B-. So as B- comes up, gate voltage is applied, current flows through R14 causing a drop there that is proportional.
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Old 14th January 2012, 03:07 PM   #47
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Default Possible substitute?

Found this device:
FQH8N100C Fairchild Semiconductor MOSFET

It's a 1000V, N-channel with a Crss of essentially zero above a Vds of 10V. Seems ideal?
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Old 5th September 2014, 12:13 AM   #48
zman01 is offline zman01  Bangladesh
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Reviving this old thread - would this MOSFET work - specs are quite similar?

http://www.weisd.com/store2/NTE2903.pdf

If suitable substitutes have been identified and tested, would also appreciate guidance on that.
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