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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
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8th Apr 2019, 10:16 am | #21 | |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Chinese power transistors
Quote:
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8th Apr 2019, 4:09 pm | #22 |
Heptode
Join Date: Oct 2008
Location: Aalborg, Denmark
Posts: 903
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Re: Chinese power transistors
Some times it's not so difficult to spot the fakes off eBay.
These 2N3055's were still wet behind the ears when I received them. Recently I bought a mix of small zener-diodes off eBay and the other day I needed a 39Vz for repairing a LAB-amp. In the bag labelled 39V were 10 Zeners and only ONE of them came anywhere near to 39V at 38,6V. The rest were below 36V. Now, would YOU trust the single Zener within range to do repairs to a LAB-2000C amplifier ? In my country they sell at +£500 used. /Torben |
8th Apr 2019, 4:55 pm | #23 |
Dekatron
Join Date: Apr 2012
Location: Wiltshire, UK.
Posts: 14,007
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Re: Chinese power transistors
It's not only popular audio transistors that are victims of fakery; the problem extends into RF power-transistors too: several 1980s Motorola "MRF"- and International Rectifier "IRF" devices as used in CB sets, ham transceivers etc are now more often fakes than not, likewise the 'integrated power-amp' blocks produced by Mitsubishi and used in old VHF/UHF commercial two-way gear.
There's no easy answer to this: paying a lot and buying from reputable mainstream dealers is no guarantee that fraud hasn't taken place somewhere in the supply-chain. At least the likes of CPC, RS etc. are going to be easier to get a refund from if the deal does turn out to be a bad one. |
8th Apr 2019, 6:12 pm | #24 |
Hexode
Join Date: Feb 2014
Location: Southampton, Hampshire, UK.
Posts: 419
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Re: Chinese power transistors
Steve,
If you do adopt the BNOS 12/25 as a design basis add in a soft start as many of these old designs were conceived in the wire fuse era and will trip modern domestic breakers on inrush. Pete |
8th Apr 2019, 8:23 pm | #25 |
Heptode
Join Date: Sep 2004
Location: Preston, Lancashire, UK.
Posts: 632
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Re: Chinese power transistors
Scary just how much fakery is out there . And good shout Pete Ill add a soft start
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11th Apr 2019, 9:46 am | #26 |
Hexode
Join Date: Jun 2011
Location: Glossop, Derbyshire, UK.
Posts: 487
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Re: Chinese power transistors
I got a pack of 2N3055 from ebay for fun and they tested with a HFE range from 30 to 100( 20-70 for a good one )
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