Ge transistor leakage,question about Russian GT404b

[Brymus]

I got a bag of 50 NPN trannies GT404b from Moscow,and darn it ,every single one tested had very excessive leakage,above .50ma but,
Whats odd is every time I would measure the leakage current with the Small Bear method it would read like .22 for 3 seconds or so then double to .44 or whatever,it always doubled the initial reading.
I googled them and the only info I could find was at the other forum and a forum in Dutch,which I translated and read.
And both places had posts about them sounding good in spite of the high leakage readings.
Does anyone know if there is something in the internal design of these that would cause them to read in that manner > a normal leakage then exactly double that ?( or any other Ge transistor for that matter )
I ask because I bought a small amount of other Russian trannies a while back that read really low Hfe and the guy I bought em from said it was due to an internal resistor between the Base and Emiter.
I am hoping a similiar issue is at play with the ones I got.
Whats even worse (or maybe better) the guy sent me the wrong bag of PNP trannies I ordered they all tested low,low leakage but low gain as well,as they were a gain range lower than the ones I ordered. (that's E-Bay for ya  )
I might just keep those at least they are usable for Rangmaster builds or something that only needs around 60 Hfe.

[kupervaser]

Hey, did you order from gordelux04?

I ordered a few times from him, I have a bag of GT404 from him. I can test some gain ranges and leakage for you if you want.
I can't really tell if I am satisfied with this ebayer. I requested transistors with gain ranges as well and he assured me he will select them. When they arrived the gain ranges were wrong. I assume he has some different methods for transistor testing. I don't think he is a bad ebayer or a cheater though, he was very friendly and was willing to swap the transistors for me when I got mad.
Anyway that Dutch forum is newtone-online I think. I come there often. Either I read that post or maybe I even wrote that post about the transistors, I need to search. Anyway I am using the PEAK transistors tester to test the gain ranges. I don't remember GT404 jump like you are describing. However keep in mind that temperature influences gain ranges en leakage. I need to buy a battery for my tester, than I will measure some gain ranges for you.

Greetz

[Johnny85]

Hey there

I've bought these off gordelux on eBay before.  It's true that he doesn't get the gains the same as measured, most of the time, but I don't really mind.

Can't help you with the leakage thing, I'm afraid, but I can confirm that these things sound pretty good, if you experiment and match up two decent ones for a Fuzz-face for example.  I've built several fuzz and bass-fuzz circuits witht these and they all sound great.  I've sold a couple of the fuzz-boxes, to professional musicians I know, and they love them.  I like gains around 90-110 for the first stage and 100-130 for the second stage, using these.

[kymar]

i have some... hfe 180 - 360 measured by mastech multimeter and it depend much on case of trans (2 variants)  

[IvIark]

Yes I got 50 x GT404B's as well and most of mine were very leaky, whereas I've had over 400 Russian PNP trannies with no leakage whatsoever.  I just think that NPN germanium's are generally crap.  I've had the same thing with AC187's

[kymar]

this is  datasheets

[Brymus]

Hey, did you order from gordelux04?

I ordered a few times from him, I have a bag of GT404 from him. I can test some gain ranges and leakage for you if you want.
I can't really tell if I am satisfied with this ebayer. I requested transistors with gain ranges as well and he assured me he will select them. When they arrived the gain ranges were wrong. I assume he has some different methods for transistor testing. I don't think he is a bad ebayer or a cheater though, he was very friendly and was willing to swap the transistors for me when I got mad.
Anyway that Dutch forum is newtone-online I think. I come there often. Either I read that post or maybe I even wrote that post about the transistors, I need to search. Anyway I am using the PEAK transistors tester to test the gain ranges. I don't remember GT404 jump like you are describing. However keep in mind that temperature influences gain ranges en leakage. I need to buy a battery for my tester, than I will measure some gain ranges for you.

Greetz

Yeah thats who I bought mine from.
They guy sent me the wrong batch of PNP too I e-mailed him and he got defensive and said I was wrong and was falsely accusing him I ordered the ones with the backwards N and he sent me the ones marked with an X with a line down the middle ,He swears he sent me the ones marked with a backwards N yet I have them and they arent the right ones.I offered to send him pics but he wont send me an e-mail address to send them too.

Thanks For all the replys,I really appreciate all the feedback guys,Bryan

[Brymus]

Hey, did you order from gordelux04?

I ordered a few times from him, I have a bag of GT404 from him. I can test some gain ranges and leakage for you if you want.
I can't really tell if I am satisfied with this ebayer. I requested transistors with gain ranges as well and he assured me he will select them. When they arrived the gain ranges were wrong. I assume he has some different methods for transistor testing. I don't think he is a bad ebayer or a cheater though, he was very friendly and was willing to swap the transistors for me when I got mad.
Anyway that Dutch forum is newtone-online I think. I come there often. Either I read that post or maybe I even wrote that post about the transistors, I need to search. Anyway I am using the PEAK transistors tester to test the gain ranges. I don't remember GT404 jump like you are describing. However keep in mind that temperature influences gain ranges en leakage. I need to buy a battery for my tester, than I will measure some gain ranges for you.

Greetz

Yes it was that forum and your posts I read,(small world huh)
If you could test the leakage and gains of yours I would be very grateful,All of mine except one(.31ma) had leakage above (.5ma)
And none had gains over 160 even though they are supposed to be between 60-250...
Thanks for your help,Bryan

[Auke Haarsma]

Well, I am also a regular at the newtone-online board

the measurements I did on the 404b's I got are depicted in this graph (hfe vs leakage in uA, not mA):



I've had a smooth and pleasent deal with gordelux. He even send me some additional diodes as a 'bonus'. Would certainly order again from him if I am looking for russian stuff.

[Brymus]

Thanks for the feedback Auke,
From your chart it looks like the majority of the ones you tested read above the minimum recomended leakage >.3ma (although slightly better than my batch) In fact my results pretty much mirror yours except I only got one piece in the .3 ma range the rest were around .5ma with some in the .7ma  and .8ma  range even a couple above .9ma (one tested above 1ma)
What is your experience with the ones that test with leakage higher than .3 ma ,Do they still work OK and sound good?
Thanks Bryan

[jrod]

I've ordered a number of transistors from the same seller including gt404's. In fact I have a batch on the way now. My experience from him has been good.

Out of all the Russian germanium's I have the gt404/402 leak the most. However, few of them have been useless and most fell in the typical Fuzz Face recommended gain range. There were some duds in the batch, but only a few. Certainly more consistant than any western ge's I have.

It's the gt313/311's that have the internal resistor, supposedly.

[Brymus]

I started thinking about temp,after getting different readings this morning than last night when it was a little warmer.
Last night when I measured them it was 77-78 degrees farenhiet ,this morning it was 71-72 they measured lower leakage.
So as a test I measured one at 75 degrees it measured a leakage of .430ma with a corrected gain of 103.
So I threw it in my fridge for 45 minutes took it straight to my breadboard and it measures a leakage of .140 ma and a corrected gain of 90.(which would be usable)
Now in the time its taken (I just checked it again) to start my browser and type the above, it measures a leakage of .410ma and a corrected gain of 103 at ambient room temp 75 degrees.    Kinda cool test IMO
Shame I cant make some kind of cooler to keep them at low leakage levels...
I checked it one more time still measures .410ma leakage.
I am going to try a few in a circuit and see how they sound I dont have anything to lose at this point.

[PRR]

They are 300mA devices. They are liable to higher Iceo than little 10mA devices.

They may also read unexpectedly in the "Small Bear" test, which may be assuming smaller devices.

> always doubled the initial reading

It could be that the self-heating in the test gives 10 degree C temp rise, which would double the leakage. However I doubt it could be exact every time.

[kupervaser]

You shouldn't pay too much attention, to the HFE and the leakage. I bet you won't hear any difference between HFE 50 and HFE 100.
Just try them in your fuzz and listen, trust your years, they are the best measurmenet device! At the end, the same ears will be judging your sound in the crowd and not multimeters.!

[Auke Haarsma]

Thanks for the feedback Auke,
From your chart it looks like the majority of the ones you tested read above the minimum recomended leakage >.3ma (although slightly better than my batch) In fact my results pretty much mirror yours except I only got one piece in the .3 ma range the rest were around .5ma with some in the .7ma  and .8ma  range even a couple above .9ma (one tested above 1ma)
What is your experience with the ones that test with leakage higher than .3 ma ,Do they still work OK and sound good?
Thanks Bryan

You're welcome!

I got 100 pieces and about 5 of them where duds. I have not had time yet to test them intensively, however, my quick tests a couple of months ago got my some real nice sounding fuzzes (FF type circuit).

[juansolo]

I got 20 GT404b's, and using RGs method, the leakage on them is 100uA-250uA, hfe is 50-110. One has low hfe of 15, and one has leakage of 305uA.  This was at around 18-20 C.
I haven't built anything with them yet, which is the ultimate test, does it sound good?

[Brymus]

Thanks again everyone very good info.

PRR  >does that mean that the leakage readings could be divided by .3 for more accuracy when using the SmallBear test ? (I used both RGs and SmallBear) Or is there some other way of factoring the 300ma devices ?

Auke  > I got 1 dead unit and 3 with gains belowe 20 in the batch of 50 PNPs
          > I got 1 dead unit and about 4 with unusable low gains in the batch 50 of NPNs (Hfe aside)
The PNP he sent me all tested as low to very low leakage and had good gain for the range he sent me(30-80Hfe),had he sent me the lot I ordered(60-150Hfe) I probably could have used 90% of the batch as it is I could use about 40% of the PNPs he sent me in Rangemasters or first stage FF.

Kupervaser  > I agree ,my ears are going to be more final than the DMM in deciding if I like them or not >I will try to test in a Rangemaster and FF circuit today,time permiting.Maybe a Tonebender too.

Juansolo  > I too tried the RG method first then the Small Bear method second,and your results were MUCH better than the batch I recieved,Kudos to you for getting a small batch with such good numbers,clearly the exception it seems with the NPN GT404b

I would like to say >
I dont think Gordelux04 is trying to cheat me or anything I just think much is getting lost in translation ,When I told him I was sent the wrong ones that I needed PNPs with higher Hfe I think he took it as meaning I tested the ones marked with the  backwards N and found them lacking.
As he replied the standard testing method is flawed and he has had these complaints before.
Not that I was accidently sent the wrong batch of transistors,which were all quite good for the ones marked by an X with a line down the middle.
I sent him an apology and tried to explain better hopefully it will get translated better this time and he will understand what happened.

[Brymus]

Auke > Its to late to modify the above post ,so to clarify I had 1 dead and 4 unusable NPN GT404b due to gain (leakage aside) not Hfe aside which is gain of course.
I was tired this morning and typed that in whilst getting the kids ready for school...
I still havent had a chance to try any hopefully later this evening.

I just heard back from Gordelux04,its clear he thinks I am complaining about the gain of the ones I ordered not that I recieved the wrong ones.
If the ones I ordered (stated gain range and leakage wise) are as good as the ones I recieved I will be very pleased indeed,when and if I get them.

[Brymus]

Ha I found them,
He sent me GT404J ,when I purchased GT404i ,so I sent him a message under the GT404J explaining they were the ones I received.
I also apologized for not knowing his language before doing business with him,making it hard for me to communicate.
I hope this will demonstrate my intentions are benign and not hostile,I understand it was a simple mistake not a purposeful intent.
Its just I needed the ones I paid for not the ones he sent,
I ordered another batch so hopefully he will take care of me.
Bryan

[joegagan]

You shouldn't pay too much attention, to the HFE and the leakage. I bet you won't hear any difference between HFE 50 and HFE 100.
Just try them in your fuzz and listen, trust your years, they are the best measurmenet device! At the end, the same ears will be judging your sound in the crowd and not multimeters.!

i could definitely tell you by ear whether a ge trans is a 100 vs. a 120.