49’er & Fake Transistors

A recent posting to Yahoo's 'GQRP' reflector spurred discussion of the growing number of fake transistors being seen on e-bay. A builder enquired about the low efficiency noted in his recently built Chinese '49er' kit.

I recently bought one of the Chinese Forty-9er transceiver kits off ebay and on receive it works well. It certainly transmits, but the power is down to 800mW and the driver transistor is getting very hot. I'm not expecting a lot of power from it, but power claims are 1.8W to 3W. I'm more concerned about the hot driver transistor. The following link shows the circuit diagram.

http://www.ebay.com/itm/DIY-kits-Frog-Sounds-HAM-Radio-QRP1-8W-CW-Transceiver-Receiver-7-023MHz-/121507448525

I've checked for spurious oscillation (a problem I've had before), but can find nothing. Does anyone have any ideas for why the transistor is getting hot?

It was suggested that the transistor in the PA may not be up to specs and even be a 'fake' as these types are commonly noted on e-bay, selling for prices that are too good to be true.
 
Without taking a close look at your built kit, my suspicion would be the PA transistor. The schematic provided in the listing to which you provided a link shows a D882 as the PA transistor. This is a 2SD882 transistor is a garden variety audio amplifier transistor at best. Some data sheets show a fT of 100 MHz. These 2SD882 transistors are listed and sold by the handful on eBay for a couple of dollars for a dozen (plus and minus). Perhaps substituting a good quality better suited to RF duty transistor would be the ticket. Perhaps something like a 2SC1971. But before you start looking for listings for a 2SC1971 be aware of the fake ones that also quite prominent on eBay and sell for only a few dollars. On eBay search for "eleflow" this is brand name of a manufacturer who is making good quality substitute devices for a number of the popular CB and HAM radio PA transistors - user name on eBay is weazle66. His listing for this particular device is 27187465609 BUT you will pay as much for this replacement PA transistor as you did for the kit ... To find out more about some of these fake replacement transistors, search for "FAKE 2SC1969 RF transistor" or "FAKE NEC & MITSUBISHI RF TRANSISTORS" on youtube. The poster has a number of such video postings. Searching Google for "fake transistors" or such will turn up much interesting.

The problem was eventually sorted out by exchanging transistors:

Firstly, thanks for all your help. Initially, I replaced the Chinese PA transistor with a BD139 and that increased power output to 1.2W and reduced the heating of the driver. Key down and it took perhaps 20s to get "finger hot", rather than 10s. Tonight I changed the driver transistor to a 2N3904 as used in the original Forty-9er and the driver heating seems to have gone away. A small heatsink on the PA transistor allows it to run at 1.4W output for 30s of keydown without any drop in power or the heatsink getting any more than warm.
Thanks for all your help and I hope this helps someone else.

A search of Youtube videos shows several builders that have split some of the RF devices open in order to compare die sizes of suspected fakes with the real thing:


Earl Andrews, VE3GTC, has gone to considerable effort to test and compare many of his transistor purchases and indicates that there are a lot of devices coming out of China that are outright fakes and have no hope of meeting the specs that you might expect. His interesting website has a lot of details about testing as well as a very comprehensive 'for sale' list of reliable devices. Earl also suggests using caution when buying e-bay Chinese electrolytics as his measurements of ESR values indicate that many do not pass specs.

If you have purchased fakes or have found a Chinese source of the real thing, please let us know ... I'm sure there are plenty of dealers selling the real thing out there.
Steve McDonald, VE7SL, is a regular contributor to AmateurRadio.com and writes from British Columbia, Canada. Contact him at [email protected].

8 Responses to “49’er & Fake Transistors”

  • Mark W4MMR:

    Couple of stories about fake electronics from China. First thing is that the Chinese are master copiers except they miss a lot of details for electronics. They will skimp on materials to keep costs down. Read the book Poorly made in China and you will get the drift.

    One time the organization I work for had to purchase H-bridge drivers in order to make production. The normal sources for the drivers, like most electronic manufacturers, make high volume of components once a year and we missed out on the buying window of which was coupled with a large draw from the auto industry for the same parts. We spent $10k cash on obtaining the h-bridge drivers from China and brought them to the US for testing. They came with a certificate of conformance (of course). The H-bridge drivers all failed testing so we dumped them.

    Issues with source unknown components from China is not a new issue. Everything needs to be tested as noted in the article to determine if the devices are the real thing. In our embedded hardware we require all components to not be sourced in China if possible. That in itself is difficult but we rely on our board houses to source appropriate and usually more expensive parts. Our suppliers audit the lots of components to ensure conformance to specification.

    Over the years in sourcing with China, our org has experienced a lot of grief, learned a lot about how the Chinese work–not saying that it is the wrong way to do things, Chinese products are just not quite to the quality levels that are expected or almost a given in today’s manufacturing environment. We have learned to keep our expectations low and to soberly consider what we source and how we work with Chinese suppliers on many levels.

  • Matt W1MST:

    Great insight, Mark! Thanks for sharing.

    According to your LinkedIn profile, your day job involves marine electrical engineering. I suspect that in your business, a bad component can be a serious problem — especially when your customer is a week from port and you can’t FedEx them a replacement! 🙂

  • peter kg5wy:

    If someone spends $10K in cash for these specific drivers and they all failed, why wouldn’t they send them back for a refund?

  • Bob DW7NIB:

    Hello,
    I am a retired Electronic technician with over 45 years of service and a Ham Radio operator,also a retired Marine living in the Philippines.

    I have a suggestion that will help all,a Facebook page with the names,email,addresses, etc. of any company selling fake parts,IE,you buy a fake part or parts then take the time to go to the page and list the above info so that others can avoid these Thieves and I think eventually we can at least put a dent into their thievery!
    I would really like to know what you think!!

    I still like to build and repair but now just for fun,but not much fun with all the fake parts.73

  • peter kg5wy:

    Good idea Bob since we are all buying from other countries these days.
    🙂

  • Keith g4jkz:

    I agree, a great idea Bob, As an ex-manager of BT’s original UK test instruments calibration centre I can only wonder now at how companies like Marconi manage, particularly with parts for unique test instruments.

  • Steve VE7SL:

    Please note that Earl’s call is VE3AB and not VE3GTC (Graham), who initially posted the inquiry.

    Steve

  • Ciprian Popica:

    I think I also had one of those bad ones, even tough before buying the kit I had read this article…. so I was happy mine was fine. Din’t lasted long as today out of the blue ( I’m still waiting for my license exam date so I can’t transmit ), it just got crazy. I didn’t know where the noise it’s coming from so I turned it off. I ended up taking the PA transistor down and…. all good. Now I have to replace it but I will wait a little as I don’t have a replacement yet. Is it ok if I still use the transceiver on receive only meanwhile ? Thank you and 73.

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