Group Buy for the Through Hole Folded Cascode CEN IV boards

[PJN]

Hi Fran,

Almost there, but have one more question. On the BOM Q7 and Q8 are shown as both being 2SK170BL is this correct. The reason I'm asking is that I got two quads (4-2SK170Bl, 4-2SJ74BL) from the DIYAUDIO store to fill Q1,2,7,8. If both Q7 and Q8 are the same then I'm short two 2SK170BL. I think that I might have some knocking around in my parts bin but don't know how well they match.

Thanks,

Paul

 

[woodturner-fran]

Hi Paul,

yes, you need a matched set of 2SK170BL for Q7 and 8 I'm afraid. You will need to match a pair for each channel.

 

[PJN]

Ok, I'll get busy. Thanks Fran.

 

[EUVL]

At the DIY store, you can get complementary quads (2x 2SK170 + 2x 2SJ74).
But you can also get NJFET quads (4x LSK170).

For two channels of the FC CEN, you need one of each type of quads.


Patrick

 

[PJN]

I managed to find a pair of Toshiba K170GR. I tested them with a transistor tester and got Id=0.38mA, @Vg=262mV, and Id=0.38mA, @Vg=264mV.

I measured the remaining LSK170 from the DIYAUDIO store and got Id=0.42mA, @Vg=295mV and Id=0.43mA and 298mV

Do you guys think that these two pairs are usable? If not I'll order a quad.

Thanks

Paul

 

[EUVL]

Best to order a quad from NicMac :
https://www.diyaudio.com/community/threads/curve-traced-2sk170-bl-toshiba-jefts-for-sale.406258/

These are from Toshiba and IMHO better than LS from DIY store.
https://www.diyaudio.com/community/...lsk170-jfet-pairs-grade-b.321649/post-7035859



Patrick

 

[PJN]

Thanks for the info.