Are these Transistors legit'?

MiXiN · Post by **MiXiN** » Sat Jan 16, 2016 6:21 pm

Can anyone with any legit' MRF237 check and compare these?

Picked these up from someone cheaply, and he claims they're new old stock and not counterfeit.

20160116_175155.jpg

20160116_175101.jpg

He has more left.

Sent from my SM-G900F using Tapatalk

s2000 · Post by **s2000** » Sat Jan 16, 2016 9:15 pm

They look just like the legit ones I have except my marking are slightly different... there was a guy on Ebay selling them for a pound many years back lol

Good transistor that one, Ive got it powering a little rig I use to test aerials with, puts out 8 watts no problem with good cooling

sinus trouble · Post by **sinus trouble** » Sat Jan 16, 2016 9:26 pm

They look kosher to me!

You could use a multimeter to check the junctions are operating as they should? or use the hfe mode if you have it on your meter? but by no means are these accurate tests!
the proof would be in building a test circuit! something like the one shown in the MRF237 datasheet!

MiXiN · Post by **MiXiN** » Sun Jan 17, 2016 12:29 am

Thanks for the replies.

My meter doesn't have an hfe function, so I'll just fit it into an old VFO PA stage at some stage to see how it does.

S2000, can I ask what markings are on yours?

s2000 · Post by **s2000** » Sun Jan 17, 2016 4:01 pm

The ones I've got are stamped motorola and marked 'MRF237 R118A'. I would imagine genuine ones have different markings depending on the batch dates etc..

MiXiN · Post by **MiXiN** » Sun Jan 17, 2016 5:56 pm

Here's a good read on spotting fakes and date codes - https://www.greatplainselectronics.com/ ... region=133

By reading this, it looks like mine are most likely the real thing. My first MRF237 marked 8940 being manufactured on the 40th week of 1989.

I'm not sure how to decipher the date of manufacture on yours, S2000.

teckniqs · Post by **teckniqs** » Sun Jan 17, 2016 7:48 pm

I've never seen fake MRF237 in the correct casing before. I've found them cheap with SD1127 and 2SC1947 but were in different casing and even had the wrong pin outs for emmiter and collector.

I had slightly sweaty fingers and accidentally wiped the print off a 1947 once. Still did around the same power output but the + and - was the wrong way around.

.....Loads of fake 2SC21971 out there which work just as good.

s2000 · Post by **s2000** » Sun Jan 17, 2016 8:17 pm

Interesting reading that, I have seen that system for date codes being used on many rf transistors. Recently bought some NOS rf transistors that had markings on them 7805 made in 5th week of 1978! If you are making prototypes of circuits, I would generally tend to look for NOS as its more likely to have been made in an era when stuff was actually manufactured properly...

You raise a good point, Ive recently been working on a new prototype circuit that needed a couple of TL071 and TL072 op amps. Got them off Ebay from someone called 'Bright Components' for what seemed like the best price. When I put the circuit together, I noticed the signal I was amplifying (19khz sine wave) looked really rough on the oscilloscope. It had spikes all over it and looked deformed. I spent hours changing other components thinking the circuit was wrong (eg poor decoupling etc). In the end I thought Id better try a different supplier of op amp so went to Maplins. As soon as it was changed over with a genuine part... problem was gone lol

Seems the Chinese are having trouble making the simplest of semiconductors these days... Oh and watch out for that Bright Components supplier, they regularly come out top when you search for stuff on Ebay. The gear is shite!

s2000 · Post by **s2000** » Sun Jan 17, 2016 8:28 pm

teckniqs wrote:I've never seen fake MRF237 in the correct casing before. I've found them cheap with SD1127 and 2SC1947 but were in different casing and even had the wrong pin outs for emmiter and collector.

I had slightly sweaty fingers and accidentally wiped the print off a 1947 once. Still did around the same power output but the + and - was the wrong way around.

.....Loads of fake 2SC21971 out there which work just as good.

Yes I have noticed that before, why is the SD1127 have the collector and emitter pins the other way round from the mrf237? Thats caused aggro before lol

teckniqs · Post by **teckniqs** » Sun Jan 17, 2016 9:31 pm

They don't if they're genuine. The SD1127 should look and work exactly the same as the MRF237 minus the gold coloured connectors and metal at the bottom of the case, and they are in a casing about half the height of a 2N4427.

s2000 · Post by **s2000** » Sun Jan 17, 2016 10:18 pm

Ah just noticed something, the datasheet I got up when I changed the part over appears to have the collector and emitter shown wrong on the datasheet...

http://pdf1.alldatasheet.com/datasheet- ... RF237.html

Its the opposite way on other manufacturers datasheets for the mrf237!

Are these Transistors legit'?

Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?

Re: Are these Transistors legit'?