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i'm on a roll... the kgsshv


kevin gilmore

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So a question for the group.  As we all know high voltage BJT's that can take the full force of the KGSSHV are going away quite quickly.  None are currently being made and I quite frankly don't see them making a comeback, certainly not as TO220 devices.  There is a new mosfet on the horizon but it's a poor substitute for the real thing.  With this in mind I used the mafia network to try and source some NOS and I've hit paydirt.  Now 2SC4686A's are all but gone but I've been offered another part which was clearly meant to be used in the same role, all specs identical plus some (like the output capacitance) are even better and it's fully isolated package too.  These are also guaranteed genuine and made in Japan. 

 

Now the catch is that I have to buy a lot of them, thousands, and the end price is unknown though I hope it comes between 2-3$ when they would reach my hands.  The 4686A is currently at 4$ from Bdent and supply in Japan is all but run out.  I would naturally sell off my stash as needed to anybody building an HV so this would be enough for a few hundred new amps.  So does this make sense to anybody?  :-[

 

 

I see no problem with that. 

 

Did this ever come to fruition? If so, I'm down for a few dozen.

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silicon carbide mosfet output version soon.

all stock parts.

too many projects in the air at the same time

 

Great news! Was actually just about to ask if you knew of any replacements for the Semisouth SiC JFETs for the all sand T2 you posted awhile back. What do you think of this one? http://www.mouser.com/ds/2/90/cree_C2M0080120D-346283.pdf

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The output capacitance is still a bit too high for most of these.  This one makes me a bit happier...  :)

 

www.cree.com/~/media/Files/Cree/Power/Data%20Sheets/C2M1000170D.PDF

 

Special SR-009 amp using these in the works. 

 

Did this ever come to fruition? If so, I'm down for a few dozen.

 

Price didn't pan out and I didn't want to drop 7k$ on transistors in one go.  I haven't stopped looking though... :)

 

I did manage to score a few thousand 2SC4686A's but they are all earmarked for KGSSHV production as I was running out of parts. 

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Oops, forgot to respond to this. Thanks KG, Inu, and Birgir! Any of these options is certainly a lot cheaper than a matched quad of XF2. Hopefully it sounds as good, too.

 

Do you guys know a good CCS for T2? Only thing I'm coming up with so far is IXTH2N170D2 which is rated at 1700V cascode with DN2540? No one actually stocks IXTH2N170D2 though and minimum order is 60 at Digikey and Future.  Mouser has the SMD version in stock. Or go with complicated original T2 CCS.

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Nevermind, did a little more digging and found an easier way if for <=500V rails. Cascode IXTP08N100D2 with IXTP01N100D. Can up current to around 50mA (edit: read wrong SOA graph, more like 35mA max) with 500V rails if I'm reading datasheets correctly. Previous option with 1700V part with Birgir's 1700V part may work for TOGTE?

Edited by mypasswordis
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Folks, we've been trumped by this piece of teutonic wizardry which will trump anything here or HeadAmp builds -  or most surely not.

 

http://www.ebay.com.au/itm/Diy-kit-OTL-superlative-highend-tube-headphone-amp-for-dyn-electrostatic-/171368973396?pt=DE_Elektronik_Computer_TV_Video_Elektronik_Verst%C3%A4rker&hash=item27e6630454

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Nevermind, did a little more digging and found an easier way if for <=500V rails. Cascode IXTP08N100D2 with IXTP01N100D. Can up current to around 50mA (edit: read wrong SOA graph, more like 35mA max) with 500V rails if I'm reading datasheets correctly. Previous option with 1700V part with Birgir's 1700V part may work for TOGTE?

 

I'd stick with the stock CCS but it can be modernized with new sand.  The TOGTE uses stacked devices and both NPN and PNP. 

 

Speaking of sand, this is a pretty sight:

 

lcG85eZh.jpg

 

That's enough for a few HV's...  ;D

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I'd stick with the stock CCS but it can be modernized with new sand.  The TOGTE uses stacked devices and both NPN and PNP. 

 

Sorry, I was unclear. I guess what I was trying to ask is, what are you using for 20mA CCS for the 009 amp? It's not safe for the IXTP01N100D by itself to run 20mA at 900V, let alone 1000V.

 

Very nice score on the 2k 2sc4686a. :)

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  • 2 weeks later...

Could you elaborate a bit on the special 009 amp in planning? I am very curious about it. 

 

The output capacitance is still a bit too high for most of these.  This one makes me a bit happier...  :)

 

www.cree.com/~/media/Files/Cree/Power/Data%20Sheets/C2M1000170D.PDF

 

Special SR-009 amp using these in the works. 

 

 

Price didn't pan out and I didn't want to drop 7k$ on transistors in one go.  I haven't stopped looking though... :)

 

I did manage to score a few thousand 2SC4686A's but they are all earmarked for KGSSHV production as I was running out of parts. 

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