A good source for 2SC4793 & 2SA1837????

[slimecity]

Looks like these are getting scarce.

Anyone know a good source for these? They are rated at 100Mhz. I may need to get them as the only substitution for pre-drivers 2SA968 & 2SC2238 in a Sansui AU-X1.

Mouser seems to carry the 2238 but not the 968 (arrgghh).

Unless anyone else knows of any other decent possible sub at the same specs?

Chur chur.

 

[Hyperion]

Any 2SC4793 or 2SA1837 you see for sale are very likely to be counterfeit, however KSC4793 and KSA1837 are direct replacements - but also getting hard to find.

You are right to be looking carefully at the replacements for these transistors, the mechanical and electronic chracteristics of the originals are difficult to match. Especially now that the above mentioned replacements availability has fallen off the edge of a cliff.

 

[Hyperion]

You could try bdent -

Here
http://www.bdent.com/nsearch.html?#...ze=15&storeid=yhst-864421581610834172249761/1

And here
http://www.bdent.com/nsearch.html?catalog=yhst-864421581610834172249761&query=2SA1837

 

[eizner23]

Good ole Ceitron in the US also has em in stock:

http://www.ceitron.com/cart/advanced_search_result.php?keywords=2SA1837

http://www.ceitron.com/cart/advanced_search_result.php?keywords=2SC4793

 

[slimecity]

Thanks peeps - I think I need to stock up on these to potentially replace those......

precious....precious.....

pre-drivers.

Bdent seems to have plenty in stock and Im pretty sure I can trust that the parts will be genuine.

 

[Alan0354]

You could try bdent -

Here
http://www.bdent.com/nsearch.html?#...ze=15&storeid=yhst-864421581610834172249761/1

And here
http://www.bdent.com/nsearch.html?catalog=yhst-864421581610834172249761&query=2SA1837

I bought 200 2SC4793 from Bdent. I use 2SA1930 as PNP.

I stocked up my transistors by the hundreds. One can never take for granted they are going to be around. Quest Component has them also.

When I received from Bdent, I paid very close attention to the marking, the package and compare with the old stock I bought from Digikey two years ago, they are identical, only the lot number are different ( obviously!!!)

This is an expensive hobby, you really have to stock up parts. I think I have enough to last my life time.


Another transistor to watch out, KSC1845. It's out of stock in most place at the moment.

 

[redk9258]

How about KSA1220A / KSC2690A? Would these work?

 

[slimecity]

How about KSA1220A / KSC2690A? Would these work?

It would be interesting if these could work - the frequency of the original parts is around 100mHz, making them hard to replace - however I note that the fT of the Ksa/ksc parts is 175mHz?

If these could work, it would save a lot of pain. I certainly haven't found a reference to this being possible in my searchings......

I bought 200 2SC4793 from Bdent. I use 2SA1930 as PNP.

Thanks Alan - I guess this means that you were happy with the parts you received from Bdent, and that I can go ahead and order them......

Another transistor to watch out, KSC1845. It's out of stock in most place at the moment.

Ironically, about the only parts I HAVE stocked up on are this one and the 992!

 

[Alan0354]

It would be interesting if these could work - the frequency of the original parts is around 100mHz, making them hard to replace - however I note that the fT of the Ksa/ksc parts is 175mHz?

If these could work, it would save a lot of pain. I certainly haven't found a reference to this being possible in my searchings......



Thanks Alan - I guess this means that you were happy with the parts you received from Bdent, and that I can go ahead and order them......



Ironically, about the only parts I HAVE stocked up on are this one and the 992!

I don't think I got to the new Bdent parts yet, I still have a lot of old stock. I only bought them like a month or so ago.

But I did measure the Vbe, they are comparable. I choose them because I need low Vbe(0.6V) and they are. Not many TO-220 transistor have Vbe this low. I don't see particular reason to suspect Bdent, people here use them, they seems to be a good size distributor.

I bought from Quest components also.

How ironic, the only parts I am low are KSC1845 and KAS992. I still have like 30 of each, but that's uncomfortably low.

 

[restorer-john]

My Japanese Data manuals stop at 2SA1836! And stops at 2SA4783. That means the transistors were fabricated with JIS numbers issued just after the 1992 edition was printed.

 

[petehall347]

https://www.avnet.com/shop/emea/p/d...bjt/toshiba/2sc4793-f-m--3074457345629690478/
https://www.avnet.com/shop/emea/p/d...bjt/toshiba/2sa1837-f-m--3074457345629690481/

you shouldn't use those up in a hurry .

 

[Alan0354]

I use this site to find transistors: https://www.findchips.com/search/tta1943

 

[slimecity]

I got these from Bdent. They look OK but.

Very shiny legs - to the point where Im a bit suspicious.

Stamped under all the "2SA1837's" and 2SC4793 is "5:9".

The weird thing is that in my little component tester I am getting a pretty uniform 221 hFe on the 2SC4793, but a much lower 9and also fairly consistent 127-135 hFe on the 2SA1837's. would this variation be normal? I thought the hFe's would be a bit closer......

 

[Alan0354]

From datasheet, hfe 4793 is minimum 100. if you look at the graph, it's about 150. Yours are on the high side. I measure the Vbe at about 10mA, Vbe is between 0.595 to 0.615V. I choose this transistor for the low Vbe.

I bought it from Bdent also. This transistor is just got discontinued, it is cheap, I just don't think there is incentive to make fake one for this cheap price.

If you are interested, read my thread that I bought the 4793: http://audiokarma.org/forums/index....-distributors-to-buy-real-transistors.779175/
I think you mean marking of 5:g, not 5:9. 5:g is the same I have.

 

[slimecity]

I just don't think there is incentive to make fake one for this cheap price

Cool, thanks Alan. I suspected this too.

Was just a bit wary of the disparity between the hFE's for each type.

 

[Alan0354]

Hfe of NPN and PNP are very very different even though they are supposed to be a match pair. That's why I failed to see the need of getting them in pairs. I picked 2SA1930 mainly by the Vbe.

Looks like you have the same lot I have, the 5:g. You saw I did write I compare in detail with the one I bought from Digikey 3 years ago and they are identical except the lot number 5:g. That's normal, they build by the lots, you don't expect the ones bought 3 year ago are from the same lot.

I even have pictures of the two for you to see. You can see in very detail the look of the lot 4:Q from digikey, the package are identical in every single detail. I doubt anyone can fake it this good.

 

[Chits]

Dudes, don't be naïve. Fake components are being made, regardless of price. I've come across dozens of fake TO-92 transistors, and these are worthless! There are certainly tons of fakes of these being made. These parts are relatively expensive, making them a very attractive target for fakers.

 

[Alan0354]

This is from Bdent, not any ebay stuffs. They seems to be a big outfit. People here order from them also.

2SC4973 has only been discontinued lately, you could still buy them in digikey and mouse at the beginning of the year. Bdent might have bough large quantity and still have old stock.

I did measure the Vbe, it is in agreement with the ones I bought from Digikey 3 years ago. I picked this by the low Vbe, most of the TO-220 transistor have higher Vbe than 0.6V at 20mA.