Jump to content


Returning Member
  • Posts

  • Joined

  • Last visited

Recent Profile Visitors

The recent visitors block is disabled and is not being shown to other users.

Rinat's Achievements

Advanced Member

Advanced Member (3/6)



  1. I am going to just make a CCS using IXTP08N100D2. "8/9/2022" is too far for me to wait.
  2. Digikey suggests to replace MJW21194G/MJW21193G with MJW21196G/ MJW21195G. The only difference I've found in datasheets is lower saturation voltage.
  3. No, thanks for the option! But MBT6429DW1T1G is cheaper (It is in stock at arrow.com), has lower capacitance, higher hfe at 50nA (it is a current in the active battery), similar noise. BCV61 has matched halves. I will think, thanks. So - do you agree that the high breakdown voltage is not required here ?
  4. BTW: A shipping date for IXCP10M90S on mouser was moved to August 2022 ((( I would try to use IXTP08N100D2 (
  5. These ones for example: https://www.mouser.com/datasheet/2/308/1/MBT6429DW1T1_D-2315127.pdf https://www.onsemi.com/pdf/datasheet/bc846bdw1t1-d.pdf https://www.analog.com/media/en/technical-documentation/data-sheets/MAT01.pdf https://toshiba.semicon-storage.com/info/docget.jsp?did=19156&prodName=HN1C03FU https://www.digikey.com/en/products/detail/linear-integrated-systems-inc/IT120-PDIP-8L/13688035 https://fscdn.rohm.com/en/products/databook/datasheet/discrete/transistor/bipolar/emx26.pdf I would try the first one or MAT01AH if I were sure that I don't need > 80v of Vce at the battery ( And I am not sure that we really need here low output capacitance. If no then there are another nice options. But I don't think that using separate single transistors is a good idea for current mirror due to temperature drift. I prefer one crystal or at least one package.
  6. A question for anyone who calculated the amplifier - what is the point in using high-voltage transistors in current mirror in the active battery ? The current through the each transistor is ~0.05 mA, Ur41 and Ur40 ~ 5 mV. It means that Uce of the right part of 2sc3381 should not be more than ~5v (It is the max Ube of 2sc3675). And the same is for the left part: Ube is 5V max -> Uce max = 5v. So - what is the point ? There are nice double transistors with lower maximum Uce, with the same capacitance, with higher hfe etc....
  7. A few thoughts about replacing transistors to a contemporary parts: 1. I thought that stn9360 is just an ersatz for 2sa1486, but it seems that it is even better than the original one. 9360 has mush higher hfe and a little lower capacitance. It means that it is more suitable for the active battery and CCSs 2. KSA1220A has lower Vbr (160v instead of 200v for 2sk216) but it is ok even in original scheme. Does it mean that 2sk214 is safe to use ? I also afraid to get lower sound quality because of poor linearity of this mosfet (. 2sk216 is much better in this term. So, I am trying to find better substitution 🙂 . I don't like to use obsolete parts. It makes me slightly nervous. Now I am going to use 216/79 but I want to build someday a "fully-contemporary parts" T2 🙂. 3. 2SC3675: FJPF2145 has lower hfe and Vbr (. I have enough 3675s but also want to substitute them in future. Maybe cascoded CCS using JFET + DMOS ? It has much better resistance(look at the photos from the book) than single-bjt CCS. Cascoded CCS measured resistance Single BJT CCS measured resistance 4) 2SK246 -> 2SK208 5) 2SC3381 -> HN4C5J . What about matching of halves ? There is no info about max difference in datasheet. Also I want to build the amp with replaceable active battery - soldered to the main board in 2 points. I don't trust mechanical connection. UPD: It looks like KSA1220A is obsolete now (official status - "last shipments")
  8. Nice! It will be interesting to hear what do you think about Maida 21st. I replacing(or reducing) now all unregulated CLC filters in favor of this power supply in my tube amp. Also I am thinking to build Maida 21st based on LT3045 and some other transistor.
  9. I've definitely helped someone, who had immediately bought all 2sk208-GR from digikey 😄. There is only an R-grade on mouser/digikey with very low Idss now (( Did someone try to buy something at arrow.com ? They have 2sk208-GR at japanese warehouse and FQP8N80C.
  10. I've been trying to understand what should I measure to be sure that a transistor is genuine, for example in case of 2SK246-GR. But what if I will replace it with 2SK208? It is still in production and it is just a SMT version of 2SK246, with lower max power dissipation (100 mW vs 300 mW). But in the original scheme of active battery power dissipation of the JFET is around 1-2 mW. So... It would be ok to use 2sk208. Am I right ? Thanks and I hope it would help someone else 🙂
  11. I can't find what current measures DY294 in the breakdown test ( In the datasheet for 2SK246 Vgds is 50V and in my measurements I have 69-73 Volts. Maybe DY294 just can't detect 0.1 mA ( Unfortunately I can't limit current to 100uA in my etracer, but I will think what can I do. I hope the measurements will not damage the FET, because it measures using pulses with duration up to 5-10 ms. But I know it is still not safe. Thanks.
  12. Is this 2sk246-GR a genuine one ? The plot is Ids (Vds) for different Vgs
  13. Hi all! I've just bought via a friend in Tokyo a few transistors in a strange japanese shop (it has not it's own site). I want to test them and if they are genuine, then I will buy more. But how should I test them ? I've measured a breakdown voltage: 230-240 volts for 2sk216/2sj79s from Japan 228-233 volts for 2sk214s from bdent.com Is it ok for genuine parts ? Is it ok that 2sk214 and 2sk216 have almost the same breakdown voltage ? I am measuring with DY294 and etracer (tube curve tracer). I am going to trace full curves for 2sk216/2sk246gr via etracer at this thursday. Do good curves mean that transistors are genuine ? If no, then what should I measure ? Thanks for help! Ps: example of breakdown measurement for 2sk214:
  14. About using 2sa1413 as a substitution of 2sa1486. Am I wrong that they looks pretty similar? I am waiting them from bdent, they are in TO-251 cases. I've found only one datasheet with this type of case for 1413: 1413 datasheet jp to-251 1413 datasheet en 2sa1486 en
  15. Thanks! I think I can use 2SA1413 everywhere with a proper heatsink. It could dissipate up to 10W with an "infinite heatsink" by datasheet. I can't find what 1486 dissipates more than 10W. But I am going to buy STN9360 and 2SA1156 as well just in case.
  • Create New...