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Old 21st September 2009, 04:47 PM   #1
diyAudio Member
Join Date: Sep 2009
Default Help identifying ancient TO-3 transistors

I have a set of old TO-3 transistors pulled from an old HarmanKardon unit. They are labeled SDT-9261 and - what I assume is the date code of 6741. Best I can tell from my measurements, these appear to be NPN with gain ranging from 7 - 17. The HK unit was a low power receiver/turntable combo unit. The manufacturer marking is a capital "S" in a vertical rectangle (STMicroelectronics maybe??) There are also 2 other TO-3's that are fairly pitted on the outside and are hard to read, but I think they are labeled 86 5043 2, then below that VFS2745K. No manufacturer marking is apparent. Any ideas? Thanks.
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Old 21st September 2009, 06:45 PM   #2
Bone is offline Bone  United Kingdom
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Join Date: Jun 2004
Location: Dorset, UK
The S in a box belongs to Solitron Devices, and the SDT start to the part no confirms that. A quick look at the Solitron web site;20Devices.htm unfortunately does not have 9261 listed.

Their search page states "If you are searching for individual part number and it is not found by the search engine, please contact the factory as Solitron Devices makes many custom parts for its customers." So I suggest you do that.

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Old 22nd September 2009, 01:54 PM   #3
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Tony - Thanks. I did email Solitron and they did tell me it was their part. But they also said it had been out of production for more than 20 years and they have no data on it.
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Old 22nd September 2009, 07:43 PM   #4
mjf is offline mjf  Austria
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Join Date: Jan 2009
Location: Austria
some of that old solitron to3 transistors are comparable with the 2n3055.
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