June 17, 201412 yr Wait for the all black KGST then... Too small to make any sense as it can only take GE tubes and not RCA's as the GE's are just a bit shorter...
June 17, 201412 yr 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.
June 17, 201412 yr Author silicon carbide mosfet output version soon. all stock parts. too many projects in the air at the same time
June 17, 201412 yr 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
June 17, 201412 yr Author notice that those are TO247. Other than that, they are great parts as long as you bias them up heavy.
June 18, 201412 yr http://www.digikey.com/product-detail/en/SCT2450KEC/SCT2450KEC-ND/4171678 Lower Ciss.
June 18, 201412 yr Author yep, due to solar/wind power stuff like this is rolling out the door. And way cheaper than the semisouth parts. Also way cheaper than the Fairchild parts which they don't seem to want to sell.
June 18, 201412 yr 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.
June 20, 201412 yr Author yep! Not quite that high unless you have big heatsinks Edited June 20, 201412 yr by kevin gilmore
June 20, 201412 yr We will probably start off at 20mA but it's also a simplified KGSSHV with the last stage removed. Pretty much a solid state KGST then.
June 25, 201412 yr 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.
June 26, 201412 yr 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 June 26, 201412 yr by mypasswordis
June 26, 201412 yr 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
June 26, 201412 yr 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: That's enough for a few HV's...
June 26, 201412 yr 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.
June 26, 201412 yr Yup if we go that high in current. No way we will go higher than say +/-450V on it.
July 10, 201411 yr 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.
July 10, 201411 yr Could you elaborate a bit on the special 009 amp in planning? I am very curious about it. Indeed. Also hoping there's some tubes in it somewhere
July 10, 201411 yr No tubes and nothing is set in stone as of yet except that it won't have tubes. We can call it a mix between the KGSSHV and the KGST.
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