Germanium transistor testing

[tjdracz]

Hey everyone! It's lazy Sunday afternoon and I wanted to do something productive with my time so I decided to measure my stash of germaniums and put it all in a spreadsheet. Unfortunately my Peak Atlas ran out of battery so had to stop doing that for a bit
Anyway, here's the link to Google Docs uploaded sheet for all of you to check:
https://docs.google.com/spreadsheet/ccc?key=0AmQTWdBVWu_DdDJHYTZLVXJkVUZhLTlVMF9xb200UlE
Might be useful if you're buying some of these parts to know what kind of hfe/leakage to expect or maybe to find some nice parts and hunt them down yourself!

I will update it as soon as I resume testing and when I get new batches of transistors.

Enjoy!

[inefficiency]

Nice. Can we add to this too? I've got a lot of testing to do soon, so I could definitely contribute a bit.

[tjdracz]

That is quite cool idea, actually! I can enable editing so you can add your own measurements

[inefficiency]

Cool. I've got some MP38s and MP20As to work through. I just need to figure out a good way of sorting them without using 100 little sealable bags.

[dbat69]

I've been doing the same thing today - so can add more to this as I have a few different ones

[tjdracz]

Okay, enabled editing, anyone with a link can contribute now

[rocket88]

well, i was going to start putting all my russian germanium data up, but i see you've beat me to it tom. i just finished sorting all of mine into gain ranges, so 80-89hfe, and only kept the usable all of the ones that are <300uA. i forgot to write down the specific leakages. but i will put up my data today if i get a chance, in fact i'll put up pictures of the bags with each groups.

oh and the MP20A's i got from our new seller were some of the best i've gotten. i bought a box of 100, so i know they were in an unopened box, all low leakage <200uA and about 20-25% of them were in the 100-110 range, with the next biggest group was 90-99hfe, followed by 80-89hfe. very little were below 70hfe, so it was a great addition to my stash.

[tjdracz]

rocket88 wrote

well, i was going to start putting all my russian germanium data up, but i see you've beat me to it tom. i just finished sorting all of mine into gain ranges, so 80-89hfe, and only kept the usable all of the ones that are <300uA. i forgot to write down the specific leakages. but i will put up my data today if i get a chance, in fact i'll put up pictures of the bags with each groups.

oh and the MP20A's i got from our new seller were some of the best i've gotten. i bought a box of 100, so i know they were in an unopened box, all low leakage <200uA and about 20-25% of them were in the 100-110 range, with the next biggest group was 90-99hfe, followed by 80-89hfe. very little were below 70hfe, so it was a great addition to my stash.

That will be nice community project, nice one guys! :)

You mean MP20A? I need to buy some stuff from that guy, seems pretty great! Mine MP20B should be slightly higher gain, the gains and leakage are pretty good if you look at my spreadsheet. Bit inconsistent but I guess it's due to the fact that they come from quite a couple of batches. Guess if they were from one box, they would be bit better. Still, one of the best russian germaniums!

Incidentally, what's your current temperature there? :P I've learned the hard way about germanium temperature inconsistencies. I've started my measurements in a little conservatory in my house, sun started shining quite strongly and within minutes, the temperature there was about 25-30 degress. I was measuring 2SB405's and I kept getting ridiculous results, all leaking like mad, some even close to 1mA. I took them back to my room, at 20 degrees and suddenly, everything is testing as expected! I think it's a fair assumption that with every 4-5 degrees, leakage will double ;)

[rocket88]

hmm, it might be that since they were from the same box they were very consistent, and yes i got MP20A's from our new bulgarian seller. i have some MP20B's and they do have higher gains, but i haven't been able to find many of them, i think i have 20-50 of them.

the temp in my house is like 70F which is like 21-22C, and i make sure i don't touch them more than a few seconds, just to connect one lead of my DCA55 to it.

fyi, no one get mad at me when they see the baggies of each transistor set, i warn you i've got a lot, like 1000 total of usable ones......

[tjdracz]

1000! That's a lot! You must have went more mad than me with the shopping spree :P I got couple of hundred and it is more than I will ever need, one of the reasons for setting up my online store ;)

[rocket88]

Well it wasn't all at one time, it's been over a few months, and it was because the shipping is nuts from Russia to the US, so if I order a lot the it's not so bad. Plus I figure with everyone else here horsing stuff, I figure I have apt of catching up to do, lol. But in all seriousness I've been asked to build things for people recently, so I need to have inventory. It's probably not 1000, and it's a wide variety of GT's and MP's, i just stopped counting when my last order from my usual supplier had 300 MP38A's. And I find it easy to get a large amount of these when they are sold in batches of 25-100 each for not a lot of money. I did get a few to try that I didn't hear anyone try like  GT109's which are smaller than a tic-tac, and MP35's. And look and the bright side you know where to get some if you can't find them. Lol

[tjdracz]

Couple more European ASY,ASX,GC types arrived today so I'll add them soon. Should have battery for Peak tomorrow and can resume the testing :)

[rocket88]

might be hard to see read, but here are all of the Russian MP series Ge transistors I have that are usable after removing the leaky/bad ones. all of these have usable leakage, but may have too low hfe for something. you can see that they are bagged into gain ranges for each transistor type. will post the GT transistors when i get a chance to take some pictures. as a note, the MP38A's i got that are coated in grey were consistently lower gain then those that are bear metal or black coated.

MP20A





MP20B


MP35


MP38A




MP39B


MP41


MP41A

[iggy]

Looking at your stash, now I'm getting germanium fever. Nice collection. What have you been building with them? And how do you like the MP20A's? Haven't gotten any of those yet.

[iggy]

So you're the guy that got all the MP38A's. I'm always late to the party it seems.

[rocket88]

haha, well one of the suppliers were looking for some for me, and they found more they they though so they offered them to me at a price too good to pass up. i'm always up to help if some people want to try them.

I've been collecting all of them for various builds from rangemasters, Ge fuzzfaces, tonebenders, etc. i was also thinking about playing around with some circuits that usually have Si transistors and replacing them with Ge to see what happens, like a Ge BMP, one knob fuzz, etc.

i also just figure that since Ge's are getting harder and harder to get for reasonable prices, i'ld grab as much as i could afford so i have them when i need them. some of them are to just try other models to see how they differ in sound, and hfe.

i still have to show at to the post the GT series i have, since i didn't make a spread sheet.

[rocket88]

also, as you can see the MP41's were really low hfe, but the MP41A were pretty good. the grey MP38A's had lower hfe on average compared to the bare metal ones and black coated ones, so beware of which ones you're buying. MP35's had relatively low hfe as well, but since most of them were in the 40's they may sound good in a fuzzface, since lower hfe russians (50's) sound pretty good.

I really like and suggest the MP20A, MP20B, MP41A, and MP38A for consistent higher hfe's, and i think they have a great warm, slightly dark tone that i really love and have searched for for years.

i still want to get my hands on some MP21's to see how they are, since i haven't heard of anyone giving them a try. i've found MP21A's, MP21B's, and MP21D's, with MP21D's being the highest hfe range.

[iggy]

what part of the world are you in? I have a collection of GE tranny's maybe we might swap a few. I'm in the US. And i have a good number that you probably won't find on Ebay. as well as a couple Russians you might be interested in.

Let me know if it's worth while.

And it does seem that even the Russians are starting to get a bit short in supply. You guys seeing this as well? or is the supply vary at times of the year?

[rocket88]

it definitly depends on which ones you're looking for. the problem is some of the major pedal companies are starting to buy them in massive amounts, at least i know dunlop has been for their Eric Johnson Ge fuzzfaces. so they are getting a little hard to find, and some are just spotty as far as availability.

also, i'm in the us as well, so i'm sure we can work something out for a trade. shoot me an email.

[tjdracz]

iggy wrote

what part of the world are you in? I have a collection of GE tranny's maybe we might swap a few. I'm in the US. And i have a good number that you probably won't find on Ebay. as well as a couple Russians you might be interested in.

Let me know if it's worth while.

And it does seem that even the Russians are starting to get a bit short in supply. You guys seeing this as well? or is the supply vary at times of the year?

I think it varies.as far as I know, most of the sellers are getting them from military warehouses, surplus, state reserves and such. Probably they just get bunch of them and only when they're gone, they get another batch
Oh, how nice would it be to live and have connections in one of these post-communist countries... I mean for a pedal builder, of course