Russian Transistors Review

[rocket88]

So I recently bought a huge amount of Russia Ge transistors and slowly been sorting through them. I figured I would post the gain and leakage spreads so that everyone can spend money on those that are worthwhile rather then have to sort through threw them all.

Most of them I've gotten before like MP38A, MP21A, GT308's, etc. but I decided to try an NPN transistor I never got before, GT404G and GT404V, after reading some good stuff about them on DIYSBF. I just finished sorting threw both and I have to say I'm more then disappointed.

The GT404V's were lower in gain 50-80hfe, but the leakages were all over the place with about 90% having leakage over .400mA. Knowing that the GT404G's were going to be higher gain I had my fingers crossed that they would be better. The gains were perfect for FuzzFaces, with most of the gains being from 80-160hfe, but again about 90% having leakage over .400mA, most were .600mA and a few were over 1mA. Good thing I only got 50 of each of these. Not sure what they can be used for.

 

[tjdracz]

How did you measure them? Did you wait for the readings to stabilize after heat increase from handing them with your fingers?
NPNs  can be bit crap, that's how it is. It's still surprising though to see them that bad. I only had pnp ones, but they had little to none leakage. Hfes were so-so, but mind you, that's not everything. Also remember that with them, the datasheet gains are specified for quite big currents, much higher than what we use in our stompboxes. Try them and use your ears or put your engineering cap on and redesign circuits for currents optimized for these transistors. Probably the first option is much more sensible ;)

[IvIark]

Yes I've got some GT404B's and they're pretty much useless.  Out of 50 two had an extremely low gain reading and so essentially faulty, and out of the other 48 only 2 had leakage that I would consider acceptable and they were close at 0.36ma.  You can still use them of course but they aren't ideal.  Still I may make 46 mojo germanium buffers and sell them on TGP for big bucks one day

[dbat69]

My experience is mixed with NPNs.  Mostly I've found European ones to be very disappointing and Russian ones to be best.  All have been tested with a DCA55.

I got 25 MP38As and these are all low leakage with gains between 40 and 80.

I also got some GT404V although I can't remember who from.  Out of 25 for leakage, 15 were under .3mA, 6 were between .3 and .5mA and the remaining 4 were over .5mA.  Gain ranges were varied from 34 to 395 (the high one had high leakage to match!).  Of the 15 good ones, most were between .2 and .3mA leakage.

Another good transistor I've come across is the 2N1304 from minifux, low leakage and gains between 40 and 80.

I got quite a few AC1xx transistors and very few are useable - the remainder might do for clipping diodes or something.

I got 10 decent OC139 transistors, although most are low gains.

[tjdracz]

What's the rationale for using npns and not pnps anyway? I know you can't daisy chain them but just get the 5 output power supply for around 20 quid and never look back. Outputs are isolated so just daisy chain npn with npn and pnp with pnp, presto!
Are there many circuits asking specifically for npn germaniums? From my experience converting classic circuits to npn means trouble quite often. Weird behaviour and such...

[rocket88]

i measured them using my DCA55, which is an amazing tool, and has been making the sorting a breeze. i didn't handle them much, but did wait for them to stabilize before measuring. the PNP 402's are great, low leakage and decent gains. as far as NPN MP38's have been great and there was one other that i have that's good, but these GT404's are just the pits. i could have just gotten a bad mix, but still very sad.

i know that i could always make a daughterboard to convert the voltage so that it can be daisy chained and just use PNP's, but you never know when you can use NPN Ge's ya know? i figure i will try to still use them some how, but still never really understood how leaky transistors affect the circuit. i know that q3 for a tonebender should be leaky, but how leaky is too leaky?

i'm still going to post all of the transistors i got, gain range, and leakages. but i can say this much so far, the only ones that have had high leakage are these, everything else has over 90% below .400mA, so they are very usable.

[Geiri]

I ordered a few batches yesterday and the guy was so nice that when eBay overcharged shipping, he contacted me and asked what I'd like to get for the shipping difference and I told him to surprise me with some nice transistors.

Thanks for this tip!