I've got some 2SA1302 and 2SC3281 transistors that I ordered from RS components in the UK. Having read a lot about counterfeit devices on this forum, I've been left wondering if the devices I have are clones (they are not marked Toshiba, but with three 45 degree arrows pointing up and left) or counterfeits.
So I set up the attached test circuit, with digital voltmeters to read the voltage across R1 and R2, and an oscilloscope to observe Vce of the transistor to ensure it was set to 5 V. V1 and V2 were supplied from my lovely TTi CPX400A bench power supply.
I tested the device up to an Ic of 6.5 A, and it worked just fine (results attached to next post)
Do you think these are genuine devices? If not, why not? Would you run any more tests? Would you bother testing the 2SA1302 devices as well?
Anyone know who makes these devices?
So I set up the attached test circuit, with digital voltmeters to read the voltage across R1 and R2, and an oscilloscope to observe Vce of the transistor to ensure it was set to 5 V. V1 and V2 were supplied from my lovely TTi CPX400A bench power supply.
I tested the device up to an Ic of 6.5 A, and it worked just fine (results attached to next post)
Do you think these are genuine devices? If not, why not? Would you run any more tests? Would you bother testing the 2SA1302 devices as well?
Anyone know who makes these devices?
Attachments
The logo you have described is the Semelab logo
www.semelab.co.uk
I don't know how they compare to the Toshiba devices but they are legit.
www.semelab.co.uk
I don't know how they compare to the Toshiba devices but they are legit.
Thanks everyone for your responses.
jacco, Magnatec is a distributer, not a manufacturer. It is possible that they sold counterfeits in the past, but now sell clones.
The transistors I have have the same logo as the transistor second on the right in the picture of the second post in the thread that you linked. However, the printing and general construction is of a much higher standard. I will post a picture later today.
I did another quick and dirty test last night, testing the beta at high frequency (1 MHz) and medium current (around 0.8 A rms). Unfortunately, I didn't have anything to hand to accurately measure the ac base current, but the gain seemed to be pretty close to what you would expect for an Ft of 30 MHz.
I'm surprised no-one's commented on the results of the first test I performed. They seem to suggest the device is behaving according to the data sheet do they not? The only thing I know for sure is that these devices were not made by Toshiba. Do semelab have the rights to produce this transistor? Or did they just develop their own with the same characteristics and then give it the same part number?
What's the easiest way to crack open the package so that I can see the die? (I have a spare that I don't mind sacrificing, I'll probably test it close to the official 2SC3281 SOA first to see if it survives).
jacco, Magnatec is a distributer, not a manufacturer. It is possible that they sold counterfeits in the past, but now sell clones.
The transistors I have have the same logo as the transistor second on the right in the picture of the second post in the thread that you linked. However, the printing and general construction is of a much higher standard. I will post a picture later today.
I did another quick and dirty test last night, testing the beta at high frequency (1 MHz) and medium current (around 0.8 A rms). Unfortunately, I didn't have anything to hand to accurately measure the ac base current, but the gain seemed to be pretty close to what you would expect for an Ft of 30 MHz.
I'm surprised no-one's commented on the results of the first test I performed. They seem to suggest the device is behaving according to the data sheet do they not? The only thing I know for sure is that these devices were not made by Toshiba. Do semelab have the rights to produce this transistor? Or did they just develop their own with the same characteristics and then give it the same part number?
What's the easiest way to crack open the package so that I can see the die? (I have a spare that I don't mind sacrificing, I'll probably test it close to the official 2SC3281 SOA first to see if it survives).
I don't think you should worry about it. RS is a good reputable supplier, ISO9000 quality systems and all. Second sourcing is a good thing; product manufacturers are not tied to one source of components, so if anything should go wrong with a batch, there is an alternative supply. I know that things can go wrong. The competition can help to reduce prices too. 
It seems to measure ok, so it is ok.
It seems to measure ok, so it is ok.hi johnny, thanks for your response.
I suppose I'm not doing this just for myself, but for the re-assurance of others too. Both RS and Farnell have been stung by the counterfeit problem in the past, and there are a few posts on this forum stating that ALL new 2SA1302 and 2SC3281 are counterfeit because they are no longer produced. It seems to me that this is not true, there are third parties who now manufacture legitimate devices. If I can supply enough credible information to demonstrate that these are 'proper' devices, that could help others make informed decisions.
I suppose I'm not doing this just for myself, but for the re-assurance of others too. Both RS and Farnell have been stung by the counterfeit problem in the past, and there are a few posts on this forum stating that ALL new 2SA1302 and 2SC3281 are counterfeit because they are no longer produced. It seems to me that this is not true, there are third parties who now manufacture legitimate devices. If I can supply enough credible information to demonstrate that these are 'proper' devices, that could help others make informed decisions.
HarryDymond said:
Thanks Harry,
did not know that, it's common for me to lag a decade behind.
Afaik, the KSA/KSC's have an identical die as the Tosh versions.
Specs of the 1943/5200s are as good/ better as SA1302/SC3281.
I would think Semelab must have had contact with Toshiba in some way.
Interesting thread, looking forward to the results.
Well, I tested a device at 30 V Vce and 4 A Ic, so 120 Watts dissipation (was mounted onto a 0.08 C/W rated force-cooled heatsink - blurry photo attached). It happily operated like this for one minute, after which I turned it off.
I, for one, am convinced that these are legitimate devices. It would also seem from the thread that jacco linked that not only are there counterfeit 'Toshibas' there are also counterfeits of 'clones'!
So, the conclusion is that RS is a source of legitimate 2SC3281 and 2SA1302 devices - quite pricey though.
Photos of devices to follow...
I, for one, am convinced that these are legitimate devices. It would also seem from the thread that jacco linked that not only are there counterfeit 'Toshibas' there are also counterfeits of 'clones'!
So, the conclusion is that RS is a source of legitimate 2SC3281 and 2SA1302 devices - quite pricey though.
Photos of devices to follow...
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