GT308B Gain Test Results

[dogtone]

Hi Folks
I just got 50 Russian GT308B (say V) Transistors. Only 1 dud in 50. all the rest test with gains from a low of 49 to a high of 57 to a high of 89.
I tried one out in a Fuzz Face type box with a BEL ac128 that I wasn't to happy with (gains of 60 for the ac128 and 66 for the GT308B) and wow what a nice surprise
tone that didn't suck. Here's a pic of the test results and one of the Fuzz box used to test them in. The holes in the card are ones I pulled to sound test.
The other thing is all of the GT308Bs tested with 0 leakage!!





I'm high on Fuzzz  

[jrod]

Nice! Those numbers are way better than the ones I've bought. What seller did you get these from?

The good ones that I have sound great in a Fuzz Face and they are very low gain.

Thanks for sharing your results!!!

Edit: Oh! Also, what method did you use to test these?

[rustypinto]

Yea those are decent numbers!

I picked up 40 of these recently: one dud, 20 at 50-60Hfe, 2 at 75Hfe and the rest at 40Hfe. They certianly do make a good, mellow fuzz face and low gain boosts. I used the 75's with other 150's i had (2N404A and a 2N1309) as Q1's in fuzz face builds, and the results were fantastic!

[IvIark]

I've had really good results with the GT308Bs I got from Orpheus on the bay.  All had zero leakage and this was the range of gains:

1 x 56 hfe
1 x 58 hfe
1 x 59 hfe
4 x 60 hfe
2 x 61 hfe
4 x 62 hfe
3 x 64 hfe
4 x 65 hfe
8 x 66 hfe
4 x 67 hfe
2 x 68 hfe
4 x 69 hfe
11 x 70 hfe
5 x 71 hfe
5 x 72 hfe
3 x 73 hfe
6 x 74 hfe
6 x 75 hfe
2 x 76 hfe
5 x 77 hfe
1 x 78 hfe
2 x 79 hfe
3 x 80 hfe
1 x 81 hfe
2 x 82 hfe
2 x 83 hfe
3 x 84 hfe
1 x 85 hfe
1 x 87 hfe

For higher gain check out the GT402B's which ranged from 78 to 193 hfe, although these are not zero leakage they were all still very low with only 2 out of 50 going above 0.60mA.  I've also recently got some GT108Gs which are tiny (smaller than metal can silicon like the BC108) and these too are higher gain, but all zero leakage like the 308s.  Not tried them in a circuit yet though.

[zombiwoof]

Most of the ones I got were in a good range for a FF.  I measured a few and the Hfe averaged around 65-80, untested for leakage.  I hear these don't have a lot of leakage, so I think they will be good.

Al

[dogtone]

I got these from eBay Member: gordelux04. They took  a good 3 weeks to get here. He was pretty good at communicating.
Looks like my set tested pretty similar to IvIark's


Good Stuff

[IvIark]

It was gordelux04 that I got the GT108Gs from.  He had batches of 100 but I requested a smaller test batch of 30 and he put a few auctions up at that quantity.  Not sure if there are any left.

[zombiwoof]

The ones I got were just plain metal, not painted like those.  I wonder if they are different ones that measure a little higher.  They were the same "spaceship" shape, though.

Al

[John Lyons]

Do the GT308s have an internal resistor (that causes the lower gain readings?)
Or was that another russian transistor?

[IvIark]

That's the GT313.  It has a resistor between base and emitter

[jrod]

Do the GT308s have an internal resistor (that causes the lower gain readings?)
Or was that another russian transistor?

Yeah, I don't think the GT308 have the internal resisitor. Like IvIark said, those were GT313 and also the NPN 311's should have them too. I sent RnFR some of my 308 to test with his Peak Atlas tester and it didn't show the resistor.

The GT308B(V) that I got from gordelux all tested within the 50's. They were the metalic, non-painted ones. I also got a few black ones elsewhere that tested a little higher, but not much.

[Brymus]

Well your luck with Gordolux04 was good, he sent me the wrong lot of PNP transistors and not only refused to send the right ones.He  denied that anyone in his employ could have made such a mistake.
Instead saying I bought the wrong lot,As it was the PNPs he sent me had almost no leakage, they were just in a really low gain range.
I ordered a lot that specd 80-150 he sent me one that specd 30-80 (data sheet specs not actual tested Hfe)The ones he sent tested at 13-60 Hfe
And I didnt order the ones he sent ,he sent the wrong lot,I tripple checked the Ebay lot #s
And yeah at least 3 weeks to get them not 7-14 days like his shipping info claims.

FWIW you can only file an Ebay claim when ordering from a USA vendor if you guys here in the states buy from overseas and dont get what you ordered you are SOL.

Keep this in mind when you think low leakage/high gain Ge transistors are overpriced from state side vendors.
After testing and sorting for leakage and gain from large lots shipped from overseas,I can see why they charge what they do for good high gain Ge's
I have heard of several lots being full of duds or like me getting the wrong lot altogether.

[John Lyons]

Oooph! Sorry, that's a drag.

[IvIark]

I don't know if it's different on US eBay, but I'm in the UK and I just had a successful claim for some capacitors I ordered from Russia that didn't show up.  No problems whatsoever in making out of country claims here.

[dogtone]

Keep this in mind when you think low leakage/high gain Ge transistors are overpriced from state side vendors.
After testing and sorting for leakage and gain from large lots shipped from overseas,I can see why they charge what they do for good high gain Ge's

What you said!
I am almost breaking even on the win/loose count on searching for pnp Ge transistors. Finding those 100-140 Hfe transistors isn't easy. Leakage is a another story.........

[IvIark]

Seriously, try the GT402B.  Out of 50, 30 of them were between 100 and 140 hfe.

[Brymus]

I don't know if it's different on US eBay, but I'm in the UK and I just had a successful claim for some capacitors I ordered from Russia that didn't show up.  No problems whatsoever in making out of country claims here.

Maybe I miss understood maybe you just can't file a claim if you order through another countrie's Ebay.
Not if the seller is in another country.
IDK

[jrod]

Seriously, try the GT402B.  Out of 50, 30 of them were between 100 and 140 hfe.

I'll second this! These are great sounding transistors for a Fuzz Face. I have also tried them in a Tone Bender MKII and I was very happy with the results. Of all the large batches of Russian ge's I've bought, these had the highest leakage, but only a few were useless.

Regarding Gordelux, I have had a mostly pleasant experience with him. The GT308B(V)'s I got from him were in a sealed box. They all tested below 60 hfe. Most were in the 50's. The only problem came from some silicon transistors that should have been around 80-100, but all well below that in the 30-40 hfe range. I cantacted him and he told me it was impossible, that they were military spec and could only fit within the data sheet parameters. I blew it off because they were so cheap and he had thrown in an extra box of 50 germaniums for free with another order.

I've known the risk of buying germanium transistors off ebay, but have actually had great luck. I would still suggest buying from known good sources like Small Bear, etc. (like Brymus said!) They will more expensive, but the extra cost may be worth the time and effort saved.

[jrod]

It was gordelux04 that I got the GT108Gs from.  He had batches of 100 but I requested a smaller test batch of 30 and he put a few auctions up at that quantity.  Not sure if there are any left.

I have been curious about these and would like to know what you think of them once you try them in a circuit. I have some GT309 that look exactly the same. Very tiny! But, sound very good!

[dogtone]

Ditto on the how the GT108G's check out.

I ordered some GT408B's and will check in next month on results
Peace