based on the only other build I have seen of the 2SK183, he used a copper electrode sandwiched in between the two heatsinks. as seen below. Here is the image.
http://www.ne.jp/asahi/evo/amp/2sk183cspp/rep.htm
http://www.ne.jp/asahi/evo/amp/2sk183cspp/rep.htm
Okay so here's a better picture of how he did it.
http://www.ne.jp/asahi/evo/amp/2sk183cspp/2sk182cspp.htm
http://www.ne.jp/asahi/evo/amp/2sk183cspp/2sk182cspp.htm
one possible way ....... anyhow - schmtc is giving a vibe of Bangkok City model made with Lego ......... at least numbers of components is somewhere there
I have ordered all the parts from amazon to make a SIT sandwich as seen in the post above. I am kind of committing myself to having it built, and tested. Call me foolish, but I am curious.
Ill make a dedicated thread once Ive made the sandwich.
Thanks ZM for being omnihelpful. I promise at least 500 porn pics!
Ill make a dedicated thread once Ive made the sandwich.
Thanks ZM for being omnihelpful. I promise at least 500 porn pics!
Does anyone have info on a grading/ranking system Yamaha may have used for the K76/J26? Came across some with a “GT” marking on the can, but not sure what to make of it. They are the earlier, non-A version. Not in my posession, or I’d do some measuring.
That’s a good idea. Just spent some time digging through all the documentation of the B-2 I could find. Lots of great reading I hadn’t come across before, but nothing yet on grading/rank. Who knows, maybe ‘GT’ has nothing to do with that.
@codyt ,
Yamaha did not document their ranking system. What I can tell you is that the early serial number B2s (first couple of thousand units) did have a ranking system. Later, Yamaha did away with the ranking and matched them manually. On the back of the vfet you would find in some cases the individual test results written on the actual vfet.
What else I can tell you is that unlike Sony ranks where each rank spans across 2.5v, the Yamaha matched sets are very tight, within few hundred mV within the entire set of 8 (good BTL candidates).
If you need specific measurements let me know, I think I have notes on a "GT" set somewhere.
Yamaha did not document their ranking system. What I can tell you is that the early serial number B2s (first couple of thousand units) did have a ranking system. Later, Yamaha did away with the ranking and matched them manually. On the back of the vfet you would find in some cases the individual test results written on the actual vfet.
What else I can tell you is that unlike Sony ranks where each rank spans across 2.5v, the Yamaha matched sets are very tight, within few hundred mV within the entire set of 8 (good BTL candidates).
If you need specific measurements let me know, I think I have notes on a "GT" set somewhere.
bingo.
you can see that in the older unit where they used a rank ( "GT" in this case) the match was not as tight as it was in later units where matched individually. ...At leat this is the conclusion I get from this short test. I have other data but did not pop up in a quick search of my HD.
why am I not surprised 🤣
The K77s are all ranked, but again, I could not locate any remanence of documentation on them. That said, I did start to capture data on them and eventually will need to complete for each rank. I did see them all, ZM included. No NPs tho... 😉
Take this with a grain of salt. More data is needed to discern between the rank ranges and weed out the outliers or tired specimens. I have not been as diligent as I should have on capturing info on all the B1s I restored, but still have plenty of opportunities to get data on all ranks.
Also note K77 sets are not as tight as those in the B2s (color means they come from the same unit). This is because of the bias balance adjustment trickery Yamaha put in the B1 circuits.
Last edited:
A follow up question on the Yamaha parts - does anyone happen to have a spice model for 2SJ26? I can make a model of my specific parts with Mike R’s SIT modeler, but I can only get it to work for N parts. I’d be fine cheating and making a mirror of the K76 by manipulating the model into a P part, but I’m at a loss there too.
Is the datasheet for the 2SK2087C in this thread? I searched but cannot find it. My Goggle Fu may be weak.