Russian Germaniums?

[alexbe]

Hello,

i could comment, these germanium transistors have letter, and it is a grade just like described in datasheet. For early types very often grade is for combination of U cb max and h21e, but not limited to.

so if you want to get best transisitors you need to choose right letters, they are often same price, because seller doesn't care. Letters are cyrillic, so do not confuse cyr. Б (latin B) and cyr. В (latin V)

Datasheet can be found here. http://www.volt-220.com/images/book/transistors.djvu

GT308V (ГТ308В) are maybe better of classical HF germanium (П403А and П416Б are almost as good), and ГТ402/404Б,Г(B,G) are maybe better of classical AF germanium (МП11A,15A,38A,41A are good too). But these GT402/404 not only have twice higher dissipation power (comparing to all P/MP), but have very good h21e linearity (against varying current).

But again letters are important, for example one letter might have h21e 100-200, next letter with h21e 50-100, next 25-50. There is absolutely no rules in letters, just consult the datasheet.

Industry/Military grades are marked as 1Т instead of ГТ, and special grades for aerospace have OC in the end. Not all items have its special grade twin. Those special grades are mainly for wider temperature range, they do not show better h21e (but can show less reverse current at room temperature, and of course tremendous reliabilty).

Yes, and these GT 108, 109, 309, 310 have small cases and small power (109 and 310 are tiny and 20 milliWatt), so if you think you need this, you can use it too.

[9Lives]

I've been playing around with some of the little ufo russians chromospere sent me. I build a fuzzface.. Pretty good. I used some in a harmonic percolator and sounded really good. The gain was only like 56, but I liked it. I just find the pin out a lil aggravating.

[jtn191]

thanks for the info, alexbe. Unfortunately I don't have a .djvu reader. I ordered some GT108s, will report here after the wait...

[jtn191]

Mine just came in. I got 10 GT308Bs...odd bc I'm 99% sure I ordered GT108s. Shipping was faster than I thought it'd be, hearing from other members. re: pinout I've had to swap the base and collector. There's rumors that these tests are inaccurate for russian transistors--a test in a circuit will be the only way to tell. I just rigged up a germanium tester...here's what I'm getting.

-30 hfe .006 ma
-43 hfe  .013 ma
8 of 10 were between 30-40 hfe
I tried one at random in Q3 of my fuzz factory and it sounds ok but is too low gain for much fuzz there...

...
the best two I've gotten so far were

51 hfe  ~.011 ma
49 hfe ~.008 ma

[alexbe]

hello jtn191,


well, GT308B should be like this, when measured at 1 mA. It's better to order GT308V then. Only i can question, Ikbr looks way too high, it typically not exceeds several microAmperes. At what voltage did you measure and can you show schematic?

Windjview http://sourceforge.net/projects/windjview/ is worth use, in my opinion. Datasheet is in russian, but there is a way to pull information you need  - transistor list at the end with page numbers, you go to that page, and when you see anything like range "50 – 100" - it's h21e (at measuring current specified somewhere near).

[raulduke]

Apologies for the thread resurrection, but I bought a load of GT308V from ebay, and the results are looking promising.



I've been using my Peak Atlas DCA55 for testing. Leakage on all the transistors, bar one, has been well under 100uA.

They have all fallen into pretty good gain ranges (see below pic). Only 1 with a hfe lower than 60.



Now its time to see what they actually sound good in!

[ch1naski]

Apologies for the thread resurrection, but I bought a load of GT308V from ebay, and the results are looking promising.



I've been using my Peak Atlas DCA55 for testing. Leakage on all the transistors, bar one, has been well under 100uA.

They have all fallen into pretty good gain ranges (see below pic). Only 1 with a hfe lower than 60.



Now its time to see what they actually sound good in!

I grabbed some from eBay and had the opposite results:(

Got a name for the seller you purchased these from, maybe he has more for sale?

Sent from my Nexus 7 using Tapatalk HD

[raulduke]

Hey dude, the guy was called valtek_2005.

Although he states the items are boxed, with datasheet, they aren't (well mine didn't arrive like that anyway).

Mine arrived in a baggy with no further info.

However, for the cost It's worth a punt eh!

Please also note I haven't tested these in a circuit yet so the jury is still out!

[ch1naski]

Thanks. I'll give those a look

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[JakeFuzz]

Yeah the GT308's I get all consistently fall around 50. What do the markings on yours say? I haven't seen that label before. Mine all say GT308V (with the V being this really weird inverted L sort of thing).

[raulduke]

Well bollocks... that first picture is actually of another lot of transistors I bought (MP16B's) 

I'll get back to you on the markings for the GT108's.

[ch1naski]

Yeah the GT308's I get all consistently fall around 50. What do the markings on yours say? I haven't seen that label before. Mine all say GT308V (with the V being this really weird inverted L sort of thing).

mine, also

Sent from my Nexus 7 using Tapatalk HD

[raulduke]

All are marked rt308b 8801

Checked the hfe for a few again as well just to be sure.

Most fall within 70-90.

The r is actually a Russian letter that resembles an r.

[garfo]

I've built mine with russian mp39's.It is very hard to get a perfect match, but once you do, it sounds amazing.
I got mine on a visit to Ukraine, I got two there and believe it or not, it was an almost perfect pair.I believeI had one rading 80hfe and the other around 150.After that I asked an ukranan friend to send me some more to Portugal and I was very disappointed.All of them were horrible in terms of leackage and it was almost impossible to find more than a pair that would have an appropriate hfe for the fuzz.But these ones sound very good though.

[midwayfair]

The r is actually a Russian letter that resembles an r.

It's a G.