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Oscillations in P3A ??
Oscillations in P3A ??
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Old 16th January 2003, 09:03 AM   #1
Stormo is offline Stormo
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Question Oscillations in P3A ??

Pls help !

I have build several versions of P3A and they where fine. I have now a +/- 42 volt version and it is oscillating very hard - 20 volt p/p probably in the Mhz area. All caps ara mounted but nothing helps. What to do ? the output is 2SC3281/2SA1302.
Btw, if i drive it hard (input 2v p/p) @ 1 Khz it stops oscillating and act OK.
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Old 16th January 2003, 09:41 AM   #2
trwh is offline trwh  United Kingdom
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Are you sure your output devices aren't fakes? The 2SC3281/2SA1302 parts you mention were discontinued some time ago. Check here:

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Old 20th January 2003, 07:58 AM   #3
Stormo is offline Stormo
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Thanks for the advice, but still i think the design shoul work.
Can anyone explain ??

I am kind of desperate.
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Old 20th January 2003, 09:34 PM   #4
Mattyo5 is offline Mattyo5
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Have you contacted Rod Elliot about it? It does sound to me like those chips need to be replaced. I don't know about where you are, but here, Digikey has the new Toshiba chips for like $2 each. The 2sc5200 and the 1943? Cheap enough. Contact Rod Elliot and let us know what he says about it.

-Matthew K. Olson
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