New Stasis front end

Thanks Zung so I took a similar approach as yours, so far I measured the Toshiba 2SA1986-R PNPs and got Hfe and Vbe curves at an average 601mA @ 36VE which is the Max Voltage my little Curve tracer can handle, and; out of a lot of 60 I got 2 groups of 11 matched to 3.91% Hfe and 0.4% Vbe between them and 5% Hfe and 0.6% Vbe across them. I think this would be good enough, not that I have more transistors anyway...

I will do the NPNs next...

2SA1986-R Matching.PNG
 
Expect a lower yield matching P & N for Hfe.
Getting opposite sex to get along is more difficult. :)

Yeap, as predicted I measured the Toshiba 2SC5358-O NPNs and got same curves at same average 601mA and again out of a lot of 60 I got 2 groups of 11 matched to a much higher 7.85% and 11.78% Hfe and similar 0.4% Vbe between them and 11.78% Hfe and 0.5% Vbe across them.

Definitely Hfe difference between PNP and NPN is big 102 vs 76 average but Vce is practically the same.
 

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At Threshold we measured output transistors for current gain, choosing the higher ones for better performance. Betas of 80+ were chosen, and we found other uses for lower gain ones.

Thanks Mr. Pass, yes I basically choose the ones with highest Beta on the lot and then started removing the ones with the lowest Beta or that were very out of the bunch until I came up with the groups, unfortunately the NPNs I got are in the lowest side of their Range for the O classification.

But if I build another set of Output Boards I will definitely choose BJTs with higher Beta.
 
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Trying to finish the Boards and mount them on the heathsinks today, while choosing the washer I found something interesting, see the picture so I’m debating between 16mm and 20mm, what do you think?

They were all tightened up to 9nm.

IMG_1096.jpg

Adding a second picture, in this one you can see the damage that the pads took with the different washers, clearly the biggest the washer the least the damage.

IMG_1098.jpg
 
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