2SA1065/2SD2489 substitutes

Jul 16, 2008 3 Replies
D

I'm working on a Technics audio amp from the late 70's with blown outputs. I've found one source (in Europe) for these transistors, but they're asking $20 each for them and I am concerned about counterfeits.



They are 150V 10A 120W, with an f(T) of 50MHz... they are faster than anything I can find out there.


  1. Is it important that I replace them with units with comparable current-bandwidth product?
  2. Can anyone recommend a substitute? I was thinking maybe MJ21195/96, but they're only 4MHz.
  3. Can anyone recommend a source for NOS Jap transistors that sells these?

Thanks Dave


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D

Consolidated Electronics Inc. is a US company, but they list stock for both devices.

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($4.00 US) and
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($11.95 US). Can't vouch for authenticity... but I've used CEI for several years and have had no problems with counterfeits.

Contact info: Toll Free: 1-800-543-3568 snipped-for-privacy@ceitron.com

Consolidated Electronics P.O. Box 20070 Dayton, Ohio 45420 USA

Dave M MasonDG44 at comcast dot net (Just substitute the appropriate characters in the address) Experience: What you get when you don\'t get what you want
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L

had

There are very few sources for bipolar transistors being manufactured using 'mesa' or 'hometaxial' chip structures. Planar parts are often labelled and marketed with the older numbers without meeting their isb capability. Valid PNP parts may be rare as hen's teeth, as they had few industrial applications, where ruggedness was appreciated ($).

Mind you, mesa parts also weren't noted for high ft. This was considered as an advantage in audio, as the components in the final stage had predetermined limits. If you see 47-150pF tacked collector to base on the final stage, they were throwing the parts' ft statistic away, in any event.

- it was virtually impossible to get PNP and NPN parts with similar current and voltage ratings to exhibit similar frequency or capacitive characteristics. (typical factor 2:1 in favour of NPN for speed). This is one reason why ft was a 'typical' (untested) characteristic with these audio parts, rather than a (tested) minimum. When local compensation was used, it was likely unequal, to take this into account.

RL

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