But Soundhappy already linked it https://www.diyaudio.com/forums/attachments/pass-labs/930117d1615296992-fet-sit-data-sheets-k77b-pdf
The recent Sony VFET SE project has transformed me into a raging fiend for SITs. I had begun a casual search for the grail a few months ago, but the Sony amp has relit my interest for obtaining these devices. The people at FAL have been very nice, but unable to help with the 2SK77B's, and I have not heard back from Digital Do Main after a few attempts (in both English and Japanese). If anyone knows of another place to look, please PM me. I'm out of ideas. Thanks!
In this project the BIG BIG IXFN140N20P is used.
Of course only because its form factor matches the 2SK77 . . .
Recently I found some interesting Lateral Mosfets, ranging from 120 to 170 to 300 watts. They look very lineair; evenly spaced transfer lines. And they have extremely low input capacitance. At 65-85 pF <<1/100th of IXFN140N20P . . . So also great for babeltalk bottom use.
I am talking about RF mosfets like the MRF9120 and MRF9180, RF Power Field Effect Transistors once used for broadband transmitters around 860 MHz and higher; N-Channel Enhancement-Mode Lateral MOSFET. These are abundant, new or refurbished; available as single or matched double Mosfet. They have a gate flap [pin] and a drain flap [pin].
Meself I was thinking to use a Hitachi Lateral but these seem fine too.
Of course only because its form factor matches the 2SK77 . . .
Recently I found some interesting Lateral Mosfets, ranging from 120 to 170 to 300 watts. They look very lineair; evenly spaced transfer lines. And they have extremely low input capacitance. At 65-85 pF <<1/100th of IXFN140N20P . . . So also great for babeltalk bottom use.
I am talking about RF mosfets like the MRF9120 and MRF9180, RF Power Field Effect Transistors once used for broadband transmitters around 860 MHz and higher; N-Channel Enhancement-Mode Lateral MOSFET. These are abundant, new or refurbished; available as single or matched double Mosfet. They have a gate flap [pin] and a drain flap [pin].
- Does anyboybody have thought on this?
Meself I was thinking to use a Hitachi Lateral but these seem fine too.
OK, I will.
Then for objectivity and to avoid my usual error-prone embroidery-style of making amplifiers:
I am working on a 2SK180 amp and would like to know it there are boards available for the top part of the amplifier; pin locations of course are no issue. [My F5 has 20cm leads and still is stable at 1 MHz]
- maybe I am running ahead of the pack and should wait untill Papa and the shop publish and offer a sequel to the 2SJ28 amplifier .. that is universal enough to fit other devices...
Then for objectivity and to avoid my usual error-prone embroidery-style of making amplifiers:
I am working on a 2SK180 amp and would like to know it there are boards available for the top part of the amplifier; pin locations of course are no issue. [My F5 has 20cm leads and still is stable at 1 MHz]
- maybe I am running ahead of the pack and should wait untill Papa and the shop publish and offer a sequel to the 2SJ28 amplifier .. that is universal enough to fit other devices...
even if role of upper mosfet is important as any component in amplifier, it isn't overly critical - counting on fact that part itself is working as Mu follower, gate driven with low impedance
so- pretty much any decent mosfet, big enough and stated as good for DC operation (SOA) should work OK
if and when you find some interesting part, fuss is worth if you can use it in some other - more critical and important position in amp
example - that thingy could be interesting in Schade iteration of Papa's Big Puck amp, which he presented in same lecture
so- pretty much any decent mosfet, big enough and stated as good for DC operation (SOA) should work OK
if and when you find some interesting part, fuss is worth if you can use it in some other - more critical and important position in amp
example - that thingy could be interesting in Schade iteration of Papa's Big Puck amp, which he presented in same lecture
And it is interesting in a classical Nemesis where originally the Lateral Mosfet 2SK135 was used by Jean Hiraga , L'Audiophile #34. Then the case=source is practical also. No mica needed.
I just tried a modern "IXYS" Mosfet with a large S with a choke load and the result is not good (amplification dependent on DC current, so there is modulation, called harmonics).
I had bought Chinese so-called IXYS power JFEts, but they were all a fraud, wrong type description.
So tried to give them a purpose with +4 volt gate instead of -6V. No idea what it actually is I got. With a square wave, in the L'Amp I noticed the turn-on time is fast but settling is slow, round edge. 
The other four are on my table.Like you I thought it was 2sk77B , They are very closely matched quad. Somewhere I read that SRCC made SSA 251 and 2sk77B are same.So I bought SSA 251. They are on the way.
what is the SRCC,seems cannot found anything in google about it
Singing Bush, what else
practically , if having part scarce as that, you'll get most of it's character in Common Source arrangement ( voltage gain, output from drain)
or upcoming Choked Singing Bush ( end of same thread), though that one still need to be verified in vivo
you have all schematics, even breadboard will do