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DIYstompboxes.com  |  DIY Stompboxes  |  Building your own stompbox  |  Russian Ge transistors 0 Members and 1 Guest are viewing this topic. « previous next »
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Author Topic: Russian Ge transistors  (Read 1430 times)
brett
Posts: 3816


Russian Ge transistors
« on: November 02, 2007, 06:31:10 PM »

Hi
for those considering getting some of these (from the fellow in Sofia), my testing of 10 devices of different types indicates:
1T313B (noname pnp =GT313B) are super low leakage (5 to 10uA), but low hFE as well (41 to 53)
1T320B (noname pnp =GT320B) are  low leakage (30 to 50uA).  Eight had hFE from 45 to 55, plus one each at 74 and 91.
103NU71 (Tesla npn) are high leakage (350 to 450uA).  One was dead, 8 had hFE from 40 to 60, and one was 125 (?!?).

Those npn jobs might be ok as buffers, or low-gain boosters, but they certainly wouldn't be my choice for a fuzzface.  It's more evidence that NPN and germanium were never a good combination.

Those PNPs are better, but the HFE is low, which might darken the tone of a fuzzface (and limit the maximum gain, of course).  I've got some GT308s on the way.  MartyMart has built a fuzzface with them and gives them a thumbs up.
cheers
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Brett Robinson
Let a hundred flowers bloom, let a hundred schools of thought contend. (Mao Zedong)
hellwood
Posts: 207


pissing off old ladies since the early 80's


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Re: Russian Ge transistors
« Reply #1 on: November 04, 2007, 12:11:38 AM »

yeah, i got 50 SFT353's as well as 50 GT308V(B)'s and the 308's were ALL ridiculously low leakage, but also averaged 50Hfe (highest 67Hfe). the SFT's are ALL sh*t! im hoping what i heard about some internal resistor giving low Hfe readings is true, otherwise, dont buy from that guy!!
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MartyMart
Posts: 6064


Martin L / Berlin for a while


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Re: Russian Ge transistors
« Reply #2 on: November 04, 2007, 04:42:30 AM »

I have not really gone for any NPN's though have a few from a"job lot"
308's have almost all been superb, low leakage and hfe's from 50 - 120
The smaller 309's also good quality, hfe's from 40 - 200 ( depending on the A or B suffix )
Have some odd and VERY large GT402's and 404's - some are NPN, two of the 402's are in
my "Rock Face" and it sounds incredible  !!!
I may have just been lucky and got a good batch, they came from Lithuania at the end of 2005 IIRC

MM.
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"Success is the ability to go from one failure to another with no loss of enthusiasm"
My Website www.martinlister.com
soulsonic
Posts: 1563


Martin C.


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Re: Russian Ge transistors
« Reply #3 on: November 04, 2007, 03:53:53 PM »

I've used GT-313s in Rangemaster style booster circuits and I like 'em. My Atlas tester tells me that the '313 has an internal biasing resistor, so it makes the hFE reading inaccurate and it changes the requirements for what bias resistors to use, but it still makes a nice loud booster.
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hellwood
Posts: 207


pissing off old ladies since the early 80's


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Re: Russian Ge transistors
« Reply #4 on: November 04, 2007, 04:31:31 PM »

the person in question selling these low Hfe transistors from Sofia, Bulgaria is orpheus 2005. has anyone ever gotten a batch of good transistors from this seller?
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MartyMart
Posts: 6064


Martin L / Berlin for a while


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Re: Russian Ge transistors
« Reply #5 on: November 04, 2007, 04:51:22 PM »

the person in question selling these low Hfe transistors from Sofia, Bulgaria is orpheus 2005. has anyone ever gotten a batch of good transistors from this seller?

Yep, just checked and my last batch of 50 GT308b's are from Orpheus and they are good trannies.

MM.
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"Success is the ability to go from one failure to another with no loss of enthusiasm"
My Website www.martinlister.com
soulsonic
Posts: 1563


Martin C.


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Re: Russian Ge transistors
« Reply #6 on: November 04, 2007, 05:04:58 PM »

I believe the '313s I got were from him as well (I didn't buy them directly, a friend gave them to me). I believe the transistors the guy from Sofia sells are a good as any of the other ones out there - you must keep in mind that these are absolutely NOT NKT275s or AC128s or OC44s, they don't just "drop in" to existing circuits like a Fuzz Face, you usually have to rework/redesign it to function properly with these different transistors. Check out something like the Trotsky Drive or the things MartyMart has done to see how effectively these things can work. I love the sounds I've been able to get from my '313 based Rangemasters, so don't diss these transistors just because they're different!
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brett
Posts: 3816


Re: Russian Ge transistors
« Reply #7 on: November 04, 2007, 08:38:37 PM »

Hi
RE:
Quote
has anyone ever gotten a batch of good transistors from this seller?

I think you'd have to say that the pnp devices above are great value for the price.  But not the npns.  Unlike other e-bay sellers, these aren't the reject devices left after people have trawled them for good ones.

RE:
Quote
My Atlas tester tells me that the '313 has an internal biasing resistor


That's interesting.  311s have an internal resistor of about 40 ohms (based on the evidence of base-emitter voltage differences much higher than the 0.3 V  expected for a germanium junction (ie about 0.41 V at Ic = 2.5 mA) .  But my 313s all showed a base-emitter difference of around 0.3 V (on my DMM), so I assumed that there's no resistor, or a very small one.  How much resistance is indicated by the tester?

cheers

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Brett Robinson
Let a hundred flowers bloom, let a hundred schools of thought contend. (Mao Zedong)
soulsonic
Posts: 1563


Martin C.


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Re: Russian Ge transistors
« Reply #8 on: November 04, 2007, 08:50:31 PM »

I don't know. The tester only tells me "hFE Inaccurate Due To B-E Resistor Shunt". Every GT313 I've tested has said this.
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brett
Posts: 3816


Re: Russian Ge transistors
« Reply #9 on: November 05, 2007, 05:43:36 AM »

My 404s in my main fuzzface have high hFE (130 and 150 - supposedly a "pair"), so it will be interesting to compare it with one loaded with the GT313s and GT320s (and GT308s when they arrive).  Unfortunately, my main amp keeps giving me short periods of life between extended periods of dead, so it might be a while before I can do the testing and post clips.
cheers
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Brett Robinson
Let a hundred flowers bloom, let a hundred schools of thought contend. (Mao Zedong)
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