Hi guys!
So, I have a few of these that I bought for use in my Cavalli-Kumisa-Kan III amp build, and am wondering if they were a particularly good choice. When I bought them I was under the impression that they do a good job, but after poking around with the forum search more it seems like people recommend some other stuff, so now I'm not so sure
So, I have a few of these that I bought for use in my Cavalli-Kumisa-Kan III amp build, and am wondering if they were a particularly good choice. When I bought them I was under the impression that they do a good job, but after poking around with the forum search more it seems like people recommend some other stuff, so now I'm not so sure
Filburt said:Hi guys!
So, I have a few of these that I bought for use in my Cavalli-Kumisa-Kan III amp build, and am wondering if they were a particularly good choice. When I bought them I was under the impression that they do a good job, but after poking around with the forum search more it seems like people recommend some other stuff, so now I'm not so sure
I also used the Y version of the 2SA and 2SC instead of the BD's in my Cavalli-Kumisa-Kan III amp. No problem whatsoever.
Remember to solder them backwards as they have different pinouts from the BD's. Add a small heatsink for each of them to make them run cooler.
Filburt said:OK! Thanks for the help, guys!
I'm wondering what I should use in the VAS. I was originally going to use 2SA970/2SC2240 but nelsonvandal recommended 2SA1016/2SC2362 instead. They seem like good transistors but I haven't seen anyone try them in this amp. Pretty tempting, though
For VAS and CCS for VAS there is not better choice from:
MPS-U10
MPS-U60
or
BF460
BF463
Those offer: Vce=250-300V, Ic=500mA, Cob=3pF.
You can make a comparison with Toshibas.
Those are obsolete some years ago (when Motorola semiconductors turned in OnSemi) but you can find them in some online stores. There are in stock yet, and their price is about 6$.
Regs
Fotios
Hi
I've used Fairchild's version of KSC1845/KSA992, well the SOT-23 version anyway. They are only rated 120V so you can use them with up to +/-55V PSU. IMO they make better VAS device then input pair. I like to have a faster transistor for the input pair. Also they can't take lots of current before the gain drops, a couple of mA. Decent noise figure though, might be better suited used as a VAS buffer in higher voltage amps....
I've used Fairchild's version of KSC1845/KSA992, well the SOT-23 version anyway. They are only rated 120V so you can use them with up to +/-55V PSU. IMO they make better VAS device then input pair. I like to have a faster transistor for the input pair. Also they can't take lots of current before the gain drops, a couple of mA. Decent noise figure though, might be better suited used as a VAS buffer in higher voltage amps....
CB240, why faster devices, you might want to look at the datasheets more carefully, the japanese devices are ft rated at 1ma, while a lot of so called faster devices are rated at 10ma, now look at their curves and see what you have at 1ma where most ltps are run. Look at the curves of these japanese devices at higher currents. Then take into effect noise, early effect, cob, gain etc.
Which device are you comparing by the way??
Indeed the nec parts are one of the cousins, 2sa872 is another, theres also a hitachi one but that is near impossible to obtain.
Which device are you comparing by the way??
Indeed the nec parts are one of the cousins, 2sa872 is another, theres also a hitachi one but that is near impossible to obtain.
off topic
Sorry to be a little of topic
All Toshiba, Sanyo, Hitachi, NEC etc Japan devices are - a little worse in Ic - copies of the old famous Motorola MPS-U10/MPS-U60/BF460-61-62/BF463-64-65.
I have informations from first hand for this.
OnSemi is sleeping a deep sleep about this game of VAS devices for mid to high voltage applications.
Regs
Fotios
Sorry to be a little of topic
All Toshiba, Sanyo, Hitachi, NEC etc Japan devices are - a little worse in Ic - copies of the old famous Motorola MPS-U10/MPS-U60/BF460-61-62/BF463-64-65.
I have informations from first hand for this.
OnSemi is sleeping a deep sleep about this game of VAS devices for mid to high voltage applications.
Regs
Fotios
In a way you right fotios, the japanese didnt invent the transistor but they sure perfected the science, today its the other way round, the west is trying to match japanese excellence.
Why would one want a transistor capable of 300ma if you only going to pass 1ma or 2 ma through it ??
If you talking of vas transistors look up 2sa1406, 2sa1538 and so many others, vastly superior to anything by onsemi.
Fotios I suggest you look very carefully at onsemi datasheets regarding IC and SOA, I dont think you doing this properly, take for instance bf422, datasheets says they can manage ic of 500 ma, in a case which can only disapate 625mw, mmmm. Now look at how the japanese trannies are rated. This goes for the bf460 too, if rated by the japanese it would most probably only been rated to 100ma or so.
Why would one want a transistor capable of 300ma if you only going to pass 1ma or 2 ma through it ??
If you talking of vas transistors look up 2sa1406, 2sa1538 and so many others, vastly superior to anything by onsemi.
Fotios I suggest you look very carefully at onsemi datasheets regarding IC and SOA, I dont think you doing this properly, take for instance bf422, datasheets says they can manage ic of 500 ma, in a case which can only disapate 625mw, mmmm. Now look at how the japanese trannies are rated. This goes for the bf460 too, if rated by the japanese it would most probably only been rated to 100ma or so.
I agree homemodder with your remarks... in general.
But... if you make a comparison of SOA curves (i have study very carefully the SOA of BF460 in my old - year of edition 1985 - databook of Motorola) between 2SA1406 and BF460, you will find that BF is superior - be it so little - from 2SA by 30mA for Vce=100V and Tc=25degC.
Unfortunatelly, i can't find any datasheet of BF on line to paste here its SOA plot for comparison. Thus i quote a comparison by hand:
Bvce---> BF460=250Vdc 2SA1406=200Vdc
Ic at 100Vce/Tc 25C---> BF460=100mA 2SA1406=70mA
200Vce/Tc 25C---> BF460=45mA 2SA1406=25mA
Also, for an Ic of 20mA (a usual thing for non symetrical VAstages for uniformity between rising and falling edge of voltage swing) BF is same in GBP with 2SA (Ic=20mA---> Ft=45MHz).
Let us to land now. The deviation indicated by comparing the SOA plots is negligible in reality... what it matters is an indication - probably - of the superior fabrication proccess of Motorola at least during the old good days... and that i trust Motorola - or OnSemi if you preffer - devices as for their reliability in the case of high voltage supply rails, as well their origin because the stamp "M" or "ON" on a device, can be visible very easy if it is fake or true... due to typing method. Also Motorola, has a good organized network of distributors around the world for many years... In Greece as i remember, from 1980. When you get a transistor from them, you can be sure that is an original "ON".
I hope, my thought to be comprehensible and to not cause misunderstanding.
And i ask your forgiveness because in my 50 i am of the old school and plenty from phobia.
Regs
Fotios
But... if you make a comparison of SOA curves (i have study very carefully the SOA of BF460 in my old - year of edition 1985 - databook of Motorola) between 2SA1406 and BF460, you will find that BF is superior - be it so little - from 2SA by 30mA for Vce=100V and Tc=25degC.
Unfortunatelly, i can't find any datasheet of BF on line to paste here its SOA plot for comparison. Thus i quote a comparison by hand:
Bvce---> BF460=250Vdc 2SA1406=200Vdc
Ic at 100Vce/Tc 25C---> BF460=100mA 2SA1406=70mA
200Vce/Tc 25C---> BF460=45mA 2SA1406=25mA
Also, for an Ic of 20mA (a usual thing for non symetrical VAstages for uniformity between rising and falling edge of voltage swing) BF is same in GBP with 2SA (Ic=20mA---> Ft=45MHz).
Let us to land now. The deviation indicated by comparing the SOA plots is negligible in reality... what it matters is an indication - probably - of the superior fabrication proccess of Motorola at least during the old good days... and that i trust Motorola - or OnSemi if you preffer - devices as for their reliability in the case of high voltage supply rails, as well their origin because the stamp "M" or "ON" on a device, can be visible very easy if it is fake or true... due to typing method. Also Motorola, has a good organized network of distributors around the world for many years... In Greece as i remember, from 1980. When you get a transistor from them, you can be sure that is an original "ON".
I hope, my thought to be comprehensible and to not cause misunderstanding.
And i ask your forgiveness because in my 50 i am of the old school and plenty from phobia.
Regs
Fotios
The difference in Ic is negligible, theres higher IC japanese trannys available if you need more current that are still superior to the motorolas. Please note they are just as old as the motorolas, only unknown and rejected by the west who like to think they were ahead of others. Like I said theres no need for higher current capability if you are not going to be even coming close to using it, what is of utmost importance in a vas is the cob. This is a common emitter configuration and aplys to ltp as well, the effective cob is the internal cob x hfe. Even just 1pf of extra cob will deteriote performance quite a bit ie 1.8pf x 100hfe versus something like 3pf versus 100hfe. The japanese trannies have greater hfe in general which is desireable for other reasons so will give you the best of 2 worlds.
Im not sure how you are looking at GBP but I can tell you that the 1406 is much faster device than bf460. Reliability of japanese devices is as good as any other if not better, their devices were overlooked by the world because of political and financial interests. There is a problem of fakes yes, but I find this as often with motorola or onsemi devices too, come buy them here in portugal, the japanese devices have markings too for authenticating. Where I come from, because of political reasons japanese devices were easier to obtain and Im more familiar with them.
The original creator of ring emiter transistors Im not sure but the earliest ones available that I know of are fujitsu, from around 1976. The 1302 is a japanese device copied by onsemi and also by fairchild and now others and this is acknowledged by them to being copies of the japanese devices on their websites. What the japanese are discarding the west is picking up, have a look at fairchild and all their copies of japanese devices. They cannot better them so they copy them, so who in reality has superior fabrication process. When I was in varsity one of our subjects was industrial technology, its main purpose was to enlighten the fact that we lag behind japanese technology in manufacturing and what to do about this by being more creative.
I am couple of years short of you fotios and I have phobia regarding western devices
Im not sure how you are looking at GBP but I can tell you that the 1406 is much faster device than bf460. Reliability of japanese devices is as good as any other if not better, their devices were overlooked by the world because of political and financial interests. There is a problem of fakes yes, but I find this as often with motorola or onsemi devices too, come buy them here in portugal
, the japanese devices have markings too for authenticating. Where I come from, because of political reasons japanese devices were easier to obtain and Im more familiar with them. The original creator of ring emiter transistors Im not sure but the earliest ones available that I know of are fujitsu, from around 1976. The 1302 is a japanese device copied by onsemi and also by fairchild and now others and this is acknowledged by them to being copies of the japanese devices on their websites. What the japanese are discarding the west is picking up, have a look at fairchild and all their copies of japanese devices. They cannot better them so they copy them, so who in reality has superior fabrication process. When I was in varsity one of our subjects was industrial technology, its main purpose was to enlighten the fact that we lag behind japanese technology in manufacturing and what to do about this by being more creative.
I am couple of years short of you fotios and I have phobia regarding western devices
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