2SC730 Transistor questions

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MiXiN
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2SC730 Transistor questions

Post by MiXiN » Thu Apr 22, 2021 5:09 pm

I've just picked up a load of Mitsubishi 2SC730 from America for around 50p a piece, and the seller claims they're new old stock.

Some have the print on the side, others on the cap.

Can somebody tell me real life gain, output power, working voltage, what 61c denotes, and if these look the real deal?

I'm familiar with spotting Motorola clones & fakes, but not Mitsubishi transistors.
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Zozo
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Re: 2SC730 Transistor questions

Post by Zozo » Thu Apr 22, 2021 5:37 pm

At first glance I'd say there genuine, All three electrodes are isolated from the case which is correct. The gold base and electrodes are also correct with genuine 2SC730. The high shine finish on the casing is also correct.

The identification labelling is usually on the side, but the ones with it on the top are probably still the real deal.
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Re: 2SC730 Transistor questions

Post by MiXiN » Thu Apr 22, 2021 6:29 pm

Nice one, Zozo. :tup

At some stage I'll put one in place of a 4427 and see how it compares.

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Re: 2SC730 Transistor questions

Post by teckniqs » Thu Apr 22, 2021 8:39 pm

MiXiN wrote:
Thu Apr 22, 2021 6:29 pm

At some stage I'll put one in place of a 4427 and see how it compares.
Should give you a bit more power (1.5w instead of 1w) and run cooler in place of 4427.

....I've had over 3w out of these on the RDVV boards.

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Re: 2SC730 Transistor questions

Post by MiXiN » Thu Apr 22, 2021 11:51 pm

Nice one Mr T - sounds good to me.

I was a big fan of the Mitsubishi 2SC1947 that could easily do 5W, but the prices of them are through the roof now.

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Re: 2SC730 Transistor questions

Post by Albert H » Fri Apr 23, 2021 2:32 am

100 mW in (from a BSX20) usually gave about a Watt in the circuit I used these with. I got a load of these from Taiwan (as I remember) in the mid-90s. Some were marked on the side, and some on the top like the ones you have. There was also a version of the device made by another Far Eastern company (JRC perhaps) that had lower gain at Band II. I made the mistake of accepting some of these other ones, and they were poor compared to the Mitsubishi ones.
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Re: 2SC730 Transistor questions

Post by radium98 » Fri Apr 23, 2021 9:47 pm

MiXiN wrote:
Thu Apr 22, 2021 11:51 pm
Nice one Mr T - sounds good to me.

I was a big fan of the Mitsubishi 2SC1947 that could easily do 5W, but the prices of them are through the roof now.
and me too and i could say they are cloned and put nothing than heat , i was scammed by 2 psc i search and post it soon for a proof , i still have 3 genuine around , they are better then that shit mrf237

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Re: 2SC730 Transistor questions

Post by MiXiN » Sat Apr 24, 2021 1:08 am

Nice one for the input, Albert.

@Radium - I quite like the MRF237, too. As far as I recall, it's easy enough to get 5W out of one.

There's plenty of legit' MRF237 around on eBay.

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Re: 2SC730 Transistor questions

Post by thewisepranker » Sat Apr 24, 2021 1:51 am

On the subject of counterfeits, the only way to see whether a transistor is genuine is to cut it open and look at the die. Markings, gold plating on the legs etc. mean nothing and are easy to reproduce.

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Re: 2SC730 Transistor questions

Post by Krakatoa » Sat Apr 24, 2021 8:02 am

I detected counterfeit by measuring the forward voltages of the junction and its capacitances (this is very important at RF) and comparing with an original device.

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Re: 2SC730 Transistor questions

Post by Zozo » Sat Apr 24, 2021 10:19 am

Never. Ever. Disassemble a device for no good reason. Lets' get this clear now with possible counterfeit devices.

1st. Visual observation to see if it's markings, package type and dimensions are the correct with the datasheet.
2nd. Measure the hFe gain or forward drop voltages to compare with either a know genuine part or datasheet.
3rd Place in a "Test Circuit" setup to characterize it's performance as given with the datasheet.

Disassemble of devices may encourage others to try this with different devices that contain hazardous chemicals, which can break-up in to small particles in the surrounding environment to be inhaled.

Plus looking at an N.P.N layer is not going to help, unless you have firstly an "electron-microscope" and something to compare it with.
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Re: 2SC730 Transistor questions

Post by thewisepranker » Sat Apr 24, 2021 4:45 pm

Markings mean nothing and dimensions are pretty much useless as well. A counterfeit is 90% of the time actually a genuine transistor pretending to be something it isn't. In my experience, it's something able to dissipate less power than the one it is pretending to be. For this reason, the package is going to be to the correct dimensions, in this case TO-39.

hfe is not a good indicator because you will find a lot of transistors in the same range, up to around 180-200 in this case. For example, it wouldn't be difficult to find a BC108 with the same gain.
It's in their interest to find a transistor close to the range so that it passes these initial tests and sometimes they choose candidates for re-marking based on what transistor they plan on pretending their fake is.
I've had devices that looked about right for what they should have been on a transistor tester so you would think that they're genuine. That is, until you try to dissipate power into them.

When you say "test circuits", I assume you mean an amplifier stage, driver board or something. These kinds of test circuits also can't tell you whether it's definitely genuine. They can only really tell you when it's obviously not what is written on the case, i.e. expecting hfe = 150 and it's actually 2000. To have a best guess of seeing whether a transistor really is what it says it is, you need to take it up to its maximum ratings, dissipating power up to the secondary breakdown line etc.
I appreciate that some bad fakes just won't work at all and you can quickly tell a bad fake in this way, but there are some good counterfeiters out there as well.

Why would you need an electron microscope? Cut open a known counterfeit transistor yourself and have a look inside! Then compare it to a genuine one. You can usually tell that it's fake even without optical magnification.
You don't even need to sacrifice good devices, keep the ones you blow up and have a look as and when you screw up - we all do it. Some people have even done this for you and put pictures up online for certain transistors.

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Re: 2SC730 Transistor questions

Post by Zozo » Sat Apr 24, 2021 6:20 pm

I do find markings are very good evidence of counterfeit devices, from T0-39 transistors to to 18DIP Integrated circuits. The last batch of 2N4427's I received from eBay the print easily came of with just your finger, which was the first alarm bell. Secondly the casing was in a highly polished can, which wasn't uncommon on some versions with the gold plated base and electrodes. But these weren't gold plated, so that's the second alarm bell.

Anyhow hFe was very high on all of them, I measured on average 160, which would indicated them have good gain, and is very near the maximum as specified on the data sheet. But in reality they didn't. I have a genuine 4427 here which works perfectly with a hFe of 22, which is not all that far from the minimum. The hFe wasn't something I'd consider checking all that much 30 years ago, if at all. But I'd say from memory 90 would be considered very good.

This would be a good experiment for those that are able to check the hFe on genuine and fake devices, to then report back and we can all see the results. I'd say the poor performing devices will all have a higher hFe than those that are genuine.

I don't need to really explain to you I'm sure when it come to counterfeit ICs that have been resurfaced, then re-printed with new markings. Those are the easiest to spot from the colour and texture on the topside of the package. You can easily prove that with a bottle of acetone and cotton bud in most cases these days.

Back to packages, I ordered some 2SC1969's last year from an eBay seller in china. In-fact I think ever seller at the time was in china for those, anyhow they all claimed as always to be "Genuine". The package type is T0-220 with some very distinctive impressions in it. The Fin is also very distinctive. When they arrived I immediately notice the package was a different size by 1mm, and the colour was jet black. The markings looked clean and engraved. which is completely wrong too. I didn't bother with them and resorted in pulling a 2SC1969 out of an old "Chicken Box" for my HF project in the end.

I did later give them to someone at the club who confirmed they was fake. He even went to the effort of putting them in circuit where as I didn't need to, as I could see they where counterfeit by "visual inspection". Anyway It gave him something to do with my e-waste.

When I said "Test Circuit" I mean the circuit used in the manufactory process to characterize the devices performance. These are usually the bare minimum in design, and if you have a large quantity to check, I see no reason why you wouldn't do it that way. I suppose you could use a piece of hardware or appliance that uses the same device to perform the test, which would be a test bed.

The electron-microscope in my opinion is the only way to make an accurate 1:1 comparison of a die?? But in all honestly I would never dissemble as device to see. If it fails all of the first 3 areas I mentioned earlier, it's not worth any more time or investment with. Besides it's not something interesting like a micro-processor with thousands of transistors.
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Re: 2SC730 Transistor questions

Post by thewisepranker » Sat Apr 24, 2021 7:13 pm

You don't need to compare every feature of the die with an electron microscope to see that it's fake. The size of the die (or lack of) will tell you in most cases.

People aren't going to the lengths of cloning dies to make counterfeits, so you haven't got to analyse the die to the nearest nanometre to see whether it's real or not. All they're doing is re-labelling inferior transistors.

The features are also not small enough to need anywhere near the magnification of an electron microscope, mediocre optics are easily enough for small transistors and the naked eye can see the features of a high power device. Cut the lid off a 2N3055 and see for yourself.

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Re: 2SC730 Transistor questions

Post by Zozo » Sat Apr 24, 2021 7:20 pm

I suppose it's possible as you say with the naked eye. But my aging eyes aren't that great these days. Id need my glasses and a magnifier too probably.

I also respect the fact that some counterfeit devices are very well done, or have been selected from a product that has an identical package.
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