Measuring Germaniums on a TC-1 for a Muffin Factory

[BuddytheReow]

I'm taking inventory before I pull the trigger on a muffin factory board. The build doc lists some npn germaniums (106NU70) with an hFE of 55-65. Before anybody starts crapping all over this post about leakage....Yes, I know using a standard, el cheapo TC-1 won't give you the true values it's measuring. I've got a few 2n211s from Small Bear right when they announced retirement (sorry, I was one of the panic buyers). My TC-1 indicates that the hFE for 2 of them are 62 and one of them is 70. I should also point out that I grabbed them with my fingers and didn't feel like waiting for them to cool down.

So, my questions is this: given the scenario above (touched by fingers briefly, 62 and 70 hFE) how off is my TC-1 in terms of gain? What margin of error does the leakage play into the readings? 1%, 10%, 25%??? I heard that because their leaky the hFE will read higher since a TC-1 doesn't understand it. Would these be ok to use in my build?

 

[jeffwhitfield]

I'm taking inventory before I pull the trigger on a muffin factory board. The build doc lists some npn germaniums (106NU70) with an hFE of 55-65. Before anybody starts crapping all over this post about leakage....Yes, I know using a standard, el cheapo TC-1 won't give you the true values it's measuring. I've got a few 2n211s from Small Bear right when they announced retirement (sorry, I was one of the panic buyers). My TC-1 indicates that the hFE for 2 of them are 62 and one of them is 70. I should also point out that I grabbed them with my fingers and didn't feel like waiting for them to cool down.

So, my questions is this: given the scenario above (touched by fingers briefly, 62 and 70 hFE) how off is my TC-1 in terms of gain? What margin of error does the leakage play into the readings? 1%, 10%, 25%??? I heard that because their leaky the hFE will read higher since a TC-1 doesn't understand it. Would these be ok to use in my build?

I’d say expect at least a 10% margin of error…which isn’t much in the grand scheme of things. So that 62 and 70 could be around 59-63 and 68-72. I would just throw them in and see how they sound. When in doubt use your ears. Just be sure and socket the board.

 

[Big Monk]

I k ow others have not shared my experiences but my TC1 measures pretty much bang-on to R.G.’s test method so I trust the TC-1 to be within 5% of R.G.

To be clear, the TC1 reads leakage without an issue in my experiences.

 

[BuddytheReow]

So, this would be acceptable then? Or should I use my other two?

 

[Chuck D. Bones]

Close enough for pedals. Like Jeff said, let your ears decide.