replacement for 2SC4793 and 2SA1837

[badboy6120]

hi everyone

I want to build Apex amplifier (HV23)(that I founded in page below (thread 44) :
MOSFET Amplifier IRFP240/IRFP9240

I found all the parts in this schematic except Q9 (2sc4793) and Q10 (2SA1837)

but the salesman suggested me to use 2SC2073 and 2SA940 instead

and I'm so confused that are they right for replacement??????
If anyone could help me I'll be grateful

[Tekko]

Pretty much any power transistor should work there, say MJL3281 and MJL1302 should work.

However dont put my word on it, but rather ask Apex himself first.

[badboy6120]

he didn't answer my mail
do you know any way I could contact him?

[jaycee]

MJE15034/MJE15035. The 2SC2073/2SA940 transistors have too slow fT.

[badboy6120]

thank you jaycee

are you sure about your suggestion? and can I count on it?

[Tekko]

Yes! JayCee is a reputable forum member, and the datasheet tells those transistors will do the job just fine.

[sajti]

Mouser has this transistors, they cost about 0.5Euro/pcs. The MJE150xx should be good replacement, only the higher internal capacitances can be problem.

Sajti

[AndrewT]

2sa1837/c4793 are nice driver transistors.
They have reasonable parameters but far from the best available.

I would not settle for lesser performance when substituting, when there are many that can at least equal 1837 performance and quite a few that can better them.
Try APEX again and be patient.

[ingenieus]

The 2SC4793 datasheet gives an fT of 70MHz. The one for the MJE15034/MJE15035 quotes an fT of 'only' 30MHz. That might or might not be significant. I don't think so myself.

[Ed LaFontaine]

There is a source that lists both of them available for $1.29 each.

Electronix Online - Computer and Electronic Parts and Supplies

I have bought other items from them that were as promised.

I have no experience with the parts you request.