kevin gilmore

chuck mangione dead at 84.

2sa1968 is in fact a PNP 900v. 2sc1968 is a 500mhz rf amplifier.

wow, you take off 2 hours to watch a movie and then all of this. if that class B output section could actually deliver 1 amp or more that is required for just about every single planar or ribbon then maybe it might actually perform correctly. but the opamp cannot possibly supply enough current to drive the output stage. all the feedback in the world won't help. and for real world loads R2 actually makes it worse. multiple feedback loops and it looks just like the squarewave of the nfca module. more like a stair step. something the AP cannot possibly measure. hint: look at the quad current dumper. class B output section. performs well within its power limit. all this to reduce the current capabilities of the power supply. all this to reduce the heat generated because the heatsinks are way to small. yes its a piece of unreliable garbage.

topping dx5ii schematic class B output stage. and they seem to be proud of this crap. discuss dx5ii.PDF

ST does not have a fab in china. but they do have a back end site in china where the silicon is cut up and packaged. so the box says made in china. Wolfspeed (formerly cree) also uses a back end site in china. which is why the c2m1000 is stamped china.

that box is 1000 pieces. the mouser price for that is $283. i cannot imagine fakes for prices that low. fake 2sj79 are going for about $15 each. which is why there are tons of fakes on ebay. the typical hfe of 200 is the only spec on the datasheet. no minimum or maximum hfe specified.

the 3rd one is the only one with the box after the cree label that matches parts i have. my parts mostly have a w13814 date code

Note, not my soldering job. battery in microscope dead too much work to get the 1:1 lens out.

i just looked at what i had in stock. F405 and F413. both work fine. logo looks printed on. not etched and not stamped either.

probably easier to change the cathode resistors on the current sources.

mauser was legit. went bankrupt more than 10 years ago. they produced firearms. german manufacturer. mouser is definitely legit. never got a fake part from them yet.

so more than a few people are getting clobbered with 300b that don't even come close to the original published western electric document. of the 7 different varieties i have, only the original 1960's manufactured western electric comes even close to the spec. and the new western electric tubes come in low vgk and high vgk versions. (The B series tubes) just means you have to mess with the resistors. and yep its a major pain in the ass. the el34 original version pretty much worked +/- a few volts no matter what tube you stuffed in there as long as they all from the same manufacturer. or build a megatronxxl now known as optimus-prime. more money, but less of a balance problem.

get yourself a high voltage transistor tester and make an adapter board or solder wires to test subject. in this case it absolutely has to have a breakdown voltage of about 640. but in any case >600 the second part is likely genuine. no one is going to pirate a $1 part. the big hfe change i am beginning to see more and more of.

150ma for -60 50ma for -250

150ma spec for +/-500 50ma spec for +/-250 150ma spec for -60 50ma for +/-15