Unfortunately no new news. I've sent countless emails to KEC and have not received a single reply. Conversation with Mouser have gone nowhere. They keep telling me its obsolete and ignore my explanation that we placed the order months before obsolescence.
So, I think it's time to close out this GB. If you paid already, let me know how you would like to proceed.
If you joined but haven't paid, let me know if you want the 2SC3503E and I'll send payment instructions.
Sorry everyone that this didn't come together as planned.
So, I think it's time to close out this GB. If you paid already, let me know how you would like to proceed.
If you joined but haven't paid, let me know if you want the 2SC3503E and I'll send payment instructions.
Sorry everyone that this didn't come together as planned.
Hi Brian
I already paid for the both the transistors. can you please send 2sc3503 and refund the balance?
thanks
kannan
I already paid for the both the transistors. can you please send 2sc3503 and refund the balance?
thanks
kannan
I contacted KEC 2 days ago and their versions are also discontinued. We use thousands of other KEC devices and so have a decent relationship with them.
The only solution I can think of is to use MPSA42 and MPSA92.
All of my designs use cascoded VAS stages and so these MPS devices have low capacitance and are good for the low voltage cascode device.
Since they can carry 500mA they are quite happy with whatever VAS current you choose. I always run my VAS stages at 25-40mA anyway and the Vceo across these MPS devices is only 2.2v so their dissipation is at 40mA Ic is 88mW.
Stephen Mantz
Zed Audio Corp.
The only solution I can think of is to use MPSA42 and MPSA92.
All of my designs use cascoded VAS stages and so these MPS devices have low capacitance and are good for the low voltage cascode device.
Since they can carry 500mA they are quite happy with whatever VAS current you choose. I always run my VAS stages at 25-40mA anyway and the Vceo across these MPS devices is only 2.2v so their dissipation is at 40mA Ic is 88mW.
Stephen Mantz
Zed Audio Corp.
Didn't they only just announce them ? 😳 Or at least this is the earliest I heard of them..
https://www.diyaudio.com/community/threads/new-transistor-source.420374/
https://www.diyaudio.com/community/threads/new-transistor-source.420374/
Hi Brian,
If this truly is the end of the GB, please ship me the 100 x 2sc3503 that I ordered, and credit my paypal account for the 100 x KSA1381 that are unavailable.
Thanks for your efforts,
MM
If this truly is the end of the GB, please ship me the 100 x 2sc3503 that I ordered, and credit my paypal account for the 100 x KSA1381 that are unavailable.
Thanks for your efforts,
MM
I am very sorry to hear that there are no news. You really put a big effort, but sometimes it is what it is.
If this is the end, please refund me, I don't need only one type of transistors unfortunatelly.
Thanks again for your big effort!
If this is the end, please refund me, I don't need only one type of transistors unfortunatelly.
Thanks again for your big effort!
sorry stephen
i dont understand you power calculation. maybe i need a coffee ;-)
if you use this 200V/300v in a cascode you "save" some voltage that you can "use" more current -bias . okay
but if you have a final voltage swing at the VAS transistor about 25V and a current - bias about 40mA i got about 1WATT.
?
kr
chris
additionally your statement that the can carry 500mA are just right for 1second about 20-25V and at 70V 10msec.
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Bit of contradictions, one person says that KEC won’t respond to emails, the other says they do. I know of late a DIYAudio member getting tubes of kta1381/ktc3503 from profusion and they were just announced as a distributor also saying more are on order. I’d edge my bets that they are not discontinued. Contact profusion to get the truth in the matter.
Running a VAS in the 25-40mA to me seems unnecessary, maybe for the pre-drivers
Running a VAS in the 25-40mA to me seems unnecessary, maybe for the pre-drivers
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sorry stephen
i dont understand you power calculation. maybe i need a coffee ;-)
if you use this 200V/300v in a cascode you "save" some voltage that you can "use" more current -bias . okay
but if you have a final voltage swing at the VAS transistor about 25V and a current - bias about 40mA i got about 1WATT.
Chris I guess you may need more than just coffee!
2.2v across a device with say 40mA flowing is 2.2 * 0.04 = 0.088w. With 25mA it is 0.055w dissipation.
I never wrote or mentioned a 25v swing at the VAS. I wrote quite clearly that I run the "inner" device of the cascoded VAS at 2.2v.
If you have 25v swing at your VAS choose another device.
I only run VAS stages cascoded.
i dont understand you power calculation. maybe i need a coffee ;-)
if you use this 200V/300v in a cascode you "save" some voltage that you can "use" more current -bias . okay
but if you have a final voltage swing at the VAS transistor about 25V and a current - bias about 40mA i got about 1WATT.
Chris I guess you may need more than just coffee!
2.2v across a device with say 40mA flowing is 2.2 * 0.04 = 0.088w. With 25mA it is 0.055w dissipation.
I never wrote or mentioned a 25v swing at the VAS. I wrote quite clearly that I run the "inner" device of the cascoded VAS at 2.2v.
If you have 25v swing at your VAS choose another device.
I only run VAS stages cascoded.
Just trying to help here, have we ruled out the mje350 transistor, or other substitutes from TTC series, BD series, etc. for complementing the 2sc3503.
MM
MM
I just picked up 60 FQA36P15 Mosfets from them "out of stock".
Had to submit a quote tho.