are there counterfeit power rf transistors - Page 1
Forum section: electronics / beginners

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: May 07, 2019, 11:11:05 am
content: There are many counterfeit parts especially commonly used parts. Has anybody seen or obtained counterfeit power RF transistors? Those are typically adhered to large ceramics or stud mounted.https://www.aliexpress.com/item/MRF9060-electronic-components-transistor/1961064451.htmlhttps://www.aliexpress.com/item/MRF282Z-TRANSISTOR/32760229754.html

author: bd139
author_rank: Super Contributor
timestamp: May 07, 2019, 11:19:19 am
content: Yeah don't buy anything like that off aliexpress. There's lots of crap out there. Worth hitting a respectable supplier for that sort of stuff:https://www.rfparts.com/https://www.rf-microwave.com/en/home/

author: Kleinstein
author_rank: Super Contributor
timestamp: May 07, 2019, 11:57:50 am
content: You can get fake 0 ohms resistors and about anything fake that is more expensive.

author: OwO
author_rank: Super Contributor
timestamp: May 07, 2019, 12:17:52 pm
content: In my experience very rare. For experimentation I would go for refurbished transistors salvaged from base stations. The price of $5 is about right for a refurbished part. I don't ever buy RF power transistors from a distributor because the prices are way too high for an experiment.

author: bd139
author_rank: Super Contributor
timestamp: May 07, 2019, 12:26:33 pm
content: I'm not so sure about the refurbs either. I had a couple of Florida microwave attenuators off aliexpress and the tabs were cut short to the case making them useless and the case was badly chipped. Looked like they'd got them out with a hammer.@Kleinstein: I've actually seen that a few years back. Before I decided to get some decent resistors I got a pack off ebay from China. The leads were like hairs and the 0 ohm resistor (single black band) was 10 ohms! Sure someone just said "eehhh, close enough!"

author: Johncanfield
author_rank: Regular Contributor
timestamp: May 07, 2019, 05:39:47 pm
content: The only way to get the genuine product for certain is to buy from Mouser, Digi-Key or one of the other part houses. Somewhere I read about how to spot a particular fake RF Mosfet - the lettering and company icon were slightly different and the leads were slightly different. I don't buy from Aliexpress but Ialwaysassume any branded electronic component I get from eBay is a Chinese fake.

author: bd139
author_rank: Super Contributor
timestamp: May 07, 2019, 06:52:36 pm
content: They're not always fake. I got a batch of AD8307's that worked perfectly.Chances of that happening is always 50/50 though.

author: wraper
author_rank: Unknown
timestamp: May 07, 2019, 07:15:36 pm
content: Quote from: bd139 on May 07, 2019, 06:52:36 pmSpecialized things with custom pinout like that are not that often fake. But you cave a chance to get salvaged part with reapplied marking and/or "upgraded" grade. Things like opamps and transistors are a big no-no.

author: bd139
author_rank: Super Contributor
timestamp: May 07, 2019, 07:26:07 pm
content: Yeah. It's not even worth it for that stuff.The thing that makes me laugh with semiconductors is the inability for people to substitute. I saw someone at the local amateur radio club spend nearly £8 on a single MPF102 JFET because he trusted the seller (littlediode) and the design demanded that JFET. The circuit didn't work so I said have you tried any other types? Answer was nope it has to be an MPF102 as the schematic says it has to be one. After some persuading stuffed a J113 in it (£0.08 - 100x less cash) and it just worked... The dude at littlediode is probably sniggering to himself that someone paid that for it while he's charging up his Tesla and all because of fear of substitution and fear of buying stuff from China.Incidentally the MPF102 is so utterly shit and the device spread is so large that half of them didn't work in circuit anyway back when they were on the common market and you had to hand select them.Actually I'm in the wrong business when I think about it.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: May 07, 2019, 07:51:14 pm
content: didn't have any problems with AD8307 from ali either; got some MRF196 as well, doing fine; but I already got fake high speed BiFet opamps; electrolytics are no good choice either from ali & co.otherwise I'm ordering a lot from those sources - jellybean and special devices and I rarely have problems with them; e.g. I got PTFE N sockets for 1.50$ the piece; used to solder a semirigid balun with the 200W iron on it, no issues.

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: May 07, 2019, 08:06:34 pm
content: How about these?https://www.ebay.com/itm/401750188937Images show genuine packaging.

author: HB9EVI
author_rank: Frequent Contributor
timestamp: May 07, 2019, 08:25:07 pm
content: it LOOKS genuine - if it is, you have to take a risk. I'll give it a try for that price.

author: wraper
author_rank: Unknown
timestamp: May 07, 2019, 08:56:15 pm
content: Quote from: LaserTazerPhaser on May 07, 2019, 08:06:34 pmChinese sellers usually sell not what on the pictures, those are just for reference.

author: LaserTazerPhaser
author_rank: Regular Contributor
timestamp: May 07, 2019, 09:02:46 pm
content: Quote from: wraper on May 07, 2019, 08:56:15 pmThey tend to charge more for listings which bare authentic part images yet ship out same fraudulent parts as those in the lower cost listings for the same parts.Would like an RF power JFET preferably GaAs or HEMT for class A audio. Perhaps also for wifi amplification. There are lots of soviet transistors, those seem authentic. Has anybody tried those?

author: David Hess
author_rank: Super Contributor
timestamp: May 07, 2019, 10:28:56 pm
content: I know they counterfeit 2N3904s and 2N3055s so they will counterfeit anything and expensive parts like power RF transistors are a prime target.

author: mc172
author_rank: Frequent Contributor
timestamp: May 08, 2019, 12:10:16 am
content: Yes. Try to find a genuine 2SC1971!

author: OwO
author_rank: Super Contributor
timestamp: May 08, 2019, 04:01:05 am
content: I have bought 2sc1971s from street vendors and even then all performed up to spec and I never found a defective one. Nowadays I don't use antiquated parts anymore so it's even less of an issue.

author: CJay
author_rank: Super Contributor
timestamp: May 08, 2019, 09:59:13 am
content: I'd be genuinely happy to find a source of 2SC1971 that work to spec and are cheap, how long ago did you find them and do you remember how much you paid for those OwO?

author: OwO
author_rank: Super Contributor
timestamp: May 08, 2019, 10:18:54 am
content: It was back in 2014/2015 and the price was 7rmb ($1.2) each. I just checked aliexpress and the most popular listing is $0.2 and has multiple reports of being fake, so I would be careful for this part number. Always read the negative reviews (1 and 2 star), a high average rating means nothing if there are lots of 1 star reviews. The taobao listings are around 10rmb now ($1.7) and probably have better chances of working, but there are also "refurbished" listings at around 2rmb.

author: bd139
author_rank: Super Contributor
timestamp: May 08, 2019, 10:25:51 am
content: I'm convinced there's no such thing as a cheap and good 2SC1971 now.There are plenty of 2SC1969 left if you want HF only.

author: OwO
author_rank: Super Contributor
timestamp: May 08, 2019, 10:32:18 am
content: If you are just looking to build VHF power amplifiers then I would go for more modern cellular base station MOSFETs like the MRF9060MR1 or MRF5S9070NR1 (search M9060M and M59070N). They are usually refurbished parts and go for ~$3, but can operate down to VHF as well (internal matching becomes no-op at VHF) and are rated for 60W. At 12V you should be able to get around 10W.

author: CJay
author_rank: Super Contributor
timestamp: May 08, 2019, 12:29:04 pm
content: I would want the TO-220 parts for refurbishing/repairing old equipment than building new, there is little point speccing obsolete parts for new builds so sources of reliable and cheap parts are always useful

author: bd139
author_rank: Super Contributor
timestamp: May 08, 2019, 12:38:01 pm
content: Can't really win with that. Everyone knows that scarcity makes money now and what stuff is worth looking at ebay sold listings. Opportunities arise if you look at parts now. For example, about 25 years ago I saw a box of about 40 Eimac tubes for £20 at a hamfest. I just skipped over it. Meh tubes. Not interested in that. Now about 40-50 quid a goI'm hoping IRF510 will go obsolete as I have over 200 of them

author: CJay
author_rank: Super Contributor
timestamp: May 08, 2019, 04:19:20 pm
content: FQP13N10 for me, I've a stash of about 200.

author: daedalux
author_rank: Contributor
timestamp: May 09, 2019, 09:23:33 pm
content: I think power RF transistors are the most counterfeited of them all. The TO-92 (small signal) and TO-220 formats in particular if the supplier is not reputable can be any crap, and many times you'll drive yourself nuts because the fake thing has the same junctions as the original and it could possibly half work for some random time.Other packages may also be counterfeited, but most of the time they tried to build it and they may be working fakes or quality control rejections. Or it may just be the part code made to spec by some proper factory. Be very aware with any final power transistor for a transceiver, as they are on high demand for repair work at the lowest price.

author: bd139
author_rank: Super Contributor
timestamp: May 09, 2019, 09:29:33 pm
content: It goes right down to 2n3904's unfortunately. I had some PNP ones a while back.

author: CJay
author_rank: Super Contributor
timestamp: May 10, 2019, 05:47:35 am
content: Quote from: daedalux on May 09, 2019, 09:23:33 pmIt's not even as sophisticated as that, they seem to just take any old TO-220, grind the top off and add a new marking, it's out and out fraud.It's not even the small quantity sellers on eBay, most of them wouldn't know a transistor from a banana and have probably never even seen the parts they sell, it's their suppliers.