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  1. #1
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    Beware of fake amplifiers on eBay using THS3091/5 part

    We were looking at an amplifier/booster to complement our current lab amplifiers and will be able to drive 20 Vpp into 50 Ω. We looked at doing a design using the TI THS3091, which has a ±250 mA capability and frequency response over 200 MHz. This will meet the 20 Vpp requirement perfectly when operating of a ±15 V supply.

    We happen to see a module advertised on eBay that seemed to incorporate this part at a very good price. There are numerous sellers offering this module, and we even found it on Alibaba.

    I am very aware of fake/cloned parts used by manufacturers, but decided to get the module as the part can always be replaced with a proper Texas Instruments part.

    Well, a few days ago, the module arrived from China, and I performed some basic tests on it in the lab.

    1) It failed miserably to drive a 50 Ω load. While the open-circuit voltage could reach in excess of 20 Vpp, the loaded voltage with minimal distortion, was only about 5.6 Vpp!
    2) Next I performed a bandwidth test and found it to be about 40 MHz, instead of the claimed 210 MHz.

    So I messaged the seller, confronting him with all the test results. I received a reply that it was passed on to the engineer. It will be very interesting to hear his reply, since they actually refer to the TI datasheet specs on their listing.

    •   Alt13th January 2018, 16:18

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    Re: Beware of fake amplifiers on eBay using THS3091/5 part

    Have you opened the part to see the die inside? this is the quick way to tell



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    Re: Beware of fake amplifiers on eBay using THS3091/5 part

    No need to do that, since I already replaced it with a genuine THS3091, and it is performing as expected. It is obviously cheap pirate clones they put in these modules to make a profit.



    •   Alt14th January 2018, 03:01

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    Re: Beware of fake amplifiers on eBay using THS3091/5 part

    I am very aware of fake/cloned parts used by manufacturers...
    Just for the sake of other consumers/ purchasers, you also may please put your observations in the comments/reviews in ebay. Others should not lose money to fake items...



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    Re: Beware of fake amplifiers on eBay using THS3091/5 part

    My advice to anybody purchasing high performance or pricey parts on eBay from China, and they are listed well below normal market value, is to expect them to be fake clones, unless it is from a verified distributor. We had a similar experience with LT1028, some PIC processors and transistors in the past. The PIC pins was so flimsy that if you plugged it into a socket and try to remove it, some pins would snap off. Luckily eBay refunded in all cases, but the time wasted waiting for these parts and then to dispute with the seller isn't worth it.

    I took it that the part will most probably be a fake, but it was still worth it to purchase the pcb module, since it is cheaper than to have it manufactured in low quantities.



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    Re: Beware of fake amplifiers on eBay using THS3091/5 part

    Amen!
    I’ve done similarly, purchased the complete assembly just for the purpose of getting the PWB itself, removing the IC and replacing it with something from Digikey.

    It is cheaper and faster than designing your own board and ordering blank boards.

    Plus all the passives are all there plus a connector or two


    1 members found this post helpful.

    •   Alt14th January 2018, 22:23

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    Re: Beware of fake amplifiers on eBay using THS3091/5 part

    So I messaged the seller, confronting him with all the test results. I received a reply that it was passed on to the engineer. It will be very interesting to hear his reply, since they actually refer to the TI datasheet specs on their listing.
    So, I got a reply from their "engineer".
    "Hello, it needs cascade, please see chip manual."



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