Author Topic: More fake parts on ebay  (Read 2396 times)

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Offline BrokenYugo

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Re: More fake parts on ebay
« Reply #25 on: May 24, 2022, 08:55:01 pm »
Most chinese parts are fake or out of order (X2216 for example : 100% dead on a batch of 10 !). The best I have seen was LTZ1000 with inside just an ordinairy zener !

There are lots of perfectly fine Chinese parts. Most rare/hard to find parts from China are fake though, especially if the price is too good to be true. But if you need some 2N3904's or some other mundane part they're usually just fine.

That's how I look at it, if you're after the cheapest component of that type and package, the parts they remark to higher specs, you're probably getting something at least close enough. Though even then, unless you're after NLA stuff, it's often a better value to just keep a cart open at LCSC or whatever.
 
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Offline thm_w

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Re: More fake parts on ebay
« Reply #26 on: May 25, 2022, 12:39:05 am »
Why would you buy from Ebay when genuine parts are available at reasonable prices from trusted suppliers:

https://lcsc.com/product-detail/Bipolar-Transistors-BJT_STMicroelectronics-ST13009_C495229.html
https://lcsc.com/product-detail/Bipolar-Transistors-BJT_Wuxi-China-Resources-Huajing-Microelectronics-3DD13009A8_C162358.html
https://www.digikey.ca/en/products/detail/onsemi/FJP13009H2TU/1054789

I would understand if the part is no longer sold, or if its very expensive, but this is a fairly generic high power TO220 NPN right?
 

Offline slbender

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Re: More fake parts on ebay
« Reply #27 on: May 25, 2022, 06:45:47 am »
I ordered FETs from China on ebay. Got NPN transistors.


If you happened to make that determination by testing those FETs with the small Chinese <$20 testers, the tester may be falsely showing a bipolar part, as some microcontroller based testers do fail when the drain and source are electrically identical with respect to the gate.  I have three of those tester boards all tend to say NPN when testing FETs.

Steven
 

Offline Paceguy

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Re: More fake parts on ebay
« Reply #28 on: May 29, 2022, 04:10:15 am »
I have learned the hard way and now buy the semiconductors and capacitors that I need for repairs from trusted  reputable North American suppliers. Ebay is OK for things like switches, connectors, etc. I could be wrong, but I'm suspicious of ebay sellers who have what appears to be an infinite supply of semiconductors. Maybe they pick up the production rejects from a production company's dumpster and sell them. :-//
 

Offline Wallace Gasiewicz

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Re: More fake parts on ebay
« Reply #29 on: May 29, 2022, 10:54:57 am »
Steven:

I see your point, I have tested FETS with some testers and got dual diode as a readout.
But these are not reading dual diode, And the transistors were tested on both modern testers and old time transistor FET testers and also show high emitter to collector resistance value.

Also, I have used about 5 of these "fake FETs" in NPN transistor applications in repairs..  They work fine as NPN transistors.
Therefore, I think they are intentionally mislabeled NPN transistors

Wally
 

Offline wraper

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Re: More fake parts on ebay
« Reply #30 on: May 29, 2022, 11:13:20 am »
Steven:

I see your point, I have tested FETS with some testers and got dual diode as a readout.
But these are not reading dual diode, And the transistors were tested on both modern testers and old time transistor FET testers and also show high emitter to collector resistance value.
BJT reads as dual diode when tested with multimeter in diode mode. Which is exactly how you should check them. Instead of attaching to a magic box and trusting what it guesses.

« Last Edit: May 29, 2022, 11:17:49 am by wraper »
 

Offline wraper

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Re: More fake parts on ebay
« Reply #31 on: May 29, 2022, 11:17:05 am »
Also, I have used about 5 of these "fake FETs" in NPN transistor applications in repairs..  They work fine as NPN transistors.
If BJT is used as a switch, N-channel MOSFET in many cases will work just fine instead of NPN BJT.
 

Offline Wallace Gasiewicz

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Re: More fake parts on ebay
« Reply #32 on: May 29, 2022, 11:58:42 am »
wraper:

I understand that.
I almost always check BJT with the diode mode first. FETs also. Saves a lot of time. Quite useful in evaluating components while on the board.
Just saying that one tester identifies some FETs as FETS and some as dual diodes.

These components were supposed to be FETs not MOSFETs
They "self identified" as NPN on multiple testers.

Yes MOSFETS make good switches. Have used enhancement MOSFETS in place of switching transistors,
 

Offline madires

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Re: More fake parts on ebay
« Reply #33 on: May 29, 2022, 12:09:56 pm »
"Genuine or fake RF output transistors?"
 

Offline Wallace Gasiewicz

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Re: More fake parts on ebay
« Reply #34 on: May 29, 2022, 12:39:59 pm »
Until Huagao, all 1969 clones were bad. I did not see one that worked, nor heard of one that worked. Maybe there were good ones, but I I have not come across a good one until Huagao. They would blow after being keyed up once or twice or at a max of three times. Just terrible.
Huagao is now making good 1969 replacements. Quite reasonable pricing. There is no other source that I can find for these transistors, no longer made by original manufacturer.
They also make other replacements including the elusive MRF 485, which I have not tried.

And to think I did all those MOSFET conversions... no longer necessary
 

Offline madires

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Re: More fake parts on ebay
« Reply #35 on: May 29, 2022, 01:16:35 pm »
If you happened to make that determination by testing those FETs with the small Chinese <$20 testers, the tester may be falsely showing a bipolar part, as some microcontroller based testers do fail when the drain and source are electrically identical with respect to the gate.  I have three of those tester boards all tend to say NPN when testing FETs.

Both OSHW firmwares (k & m) detect JFETs with symmetric source and drain (it's also shown on the display). Very old firmware versions have a problem detecting a JFET with a low I_DSS (thinking it's a Germanium BJT).
 

Offline madires

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Re: More fake parts on ebay
« Reply #36 on: May 29, 2022, 01:33:58 pm »
Also, I have used about 5 of these "fake FETs" in NPN transistor applications in repairs..  They work fine as NPN transistors.
Therefore, I think they are intentionally mislabeled NPN transistors

Yep, it's intentional. I know of a few hobbyists who bought n-ch JFETs and got NPNs. It's still happening.
 


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