A970/C2240 vs A1145/C2705

Replace old 2SA970/2SC2240 transistors with new 2SA1145/2SC2705 transistors

  • No leave good enough alone

    Votes: 9 90.0%

  • Yes the bigger ones are better anyway

    Votes: 1 10.0%

  • Yes just because they will be new and matched pairs

    Votes: 0 0.0%
  • Total voters
    10
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#21
I should have clarified that the full MPN for the On Semi I have is KSC3505DSTU.

I must say that I wasn't keen at all on the full plastic to126, never seen those before...I mean...whats the point?

Also, that i recently bought some Toshiba 2SA1020 and 2SC2655, and all of each type were very close indeed in Hfe.
The PNP A1020 were almost all identical hFe
Out of the NPNs I got maybe a quarter exact matches and the rest about 10% or so out.

I bought these for possible use as a pre driver.

I'm curious why the 300V C3503 is even being talked about....
Does anyone seriously need a 300V VAS transistor?
Using MJE340/350 is bad enough, surely?
 
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#24
KSC3503/KSA1381 has worse quasi saturation characteristic. But in the Marantz it is no problem, as the input stages are running with about 1mA, and the VAS running with 4-5mA. With this current this problem is negligible.
I use this pair in cascode stages, where the different hfe is not critical.
 
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#25
mondogenerator said:
I'm curious why the 300V C3503 is even being talked about....
Click to expand...

Max Vcb is not very relevant, but you do need one at least +120v in most VAS stages anyway.

The KSC3503 is one of the only through-hole VAS transistors available today that have a decent response, or even have an output capacitance under 5pf.

As I stated before however, somewhere deep in our subconscious, we know that the K stands for kompromise.
 
#27
It appears that Toshiba underrated their device by a massive margin. The attached is from 2SA1360 datasheet, doesn't look that fantastic. Comparing with the curve tracer readings of the same device shown in the thread, if genuine and accurate, Toshiba's datashheet seems to be referring to a wrong part.
IMG_20211125_074546.jpg
 
#29
I am aware of these graphs and, from my experience, try to confirm what I measure. My whole professional career I've been measuring "invisible" quantities. I am a chemist.

I have done these measurements side-by-side and I have verified wiring. If there is some source of errors they should reflect similarly (not, equally) on every measurement.

But, as sajti has stated, this "shortcoming" can be avoided by clever selection of operating parameters. Unfortunately, just in the design stage.

I will investigate this subject further.
 
#30
Berlusconi said:
Please, read the PM
Click to expand...

Thank you sir. YHM.

I'll be sending these but really the Sanyo is the one I'm most interested in:

  • Sanyo 2sc3503/2sa1381
  • Used pull Toshiba 2sc2240
  • Used pull Toshiba 2sc3423
  • New Toshiba 2sc7205/2sa1145 (The ones I had to fly to Russia, bribe an oligarch for a heli drop, then liberate them from an NK bunker and sneak back through the DMZ to get ...but then decided I didn't need ...but evidently they're better than the 3503/1381s I replaced them with so maybe I do)
  • Toshiba 2sc2713/2sa1163 and Fairchild FJV992/FJV1845 (The 2240 vs. 1845 battle lives on in SMD format)
  • "Toshiba" 2sc3423/2sa1360 clones
  • Toshiba TTA004/TTC004
 
#31
Thank you for entrusting me such a fortune.

I will do my best to return them to you undamaged. Please use priority post even though our post is very reliable. By the way, I am from a midget country with less population than a suburb of some larger cities. (Beauty isn't in size.)

And, by the way my gut tells me that I and qwadrofonik have a great deal in common.

Cheers
 
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#34
kwadrofonik said:
Max Vcb is not very relevant, but you do need one at least +120v in most VAS stages anyway.

The KSC3503 is one of the only through-hole VAS transistors available today that have a decent response, or even have an output capacitance under 5pf.

As I stated before however, somewhere deep in our subconscious, we know that the K stands for kompromise.
Click to expand...

Of course you require one device with Vce of 120V to 150V...that is plain.

But the compromises in architecture for HV BJTs make MJE340 and its kind less than appealing? KSC3503 included.

So, someone doesn't want to use BD139/140. So they try MJE340/350, which improves in some ways and compromises heavily in others.

So why not just use a 150Vce transistor?

I have plenty of generics which *seem* to work well enough, I only wish I had the time, equipment, and capability of Berlusconi to test them.

I have a few 150V TH BJTs which *may* work for VAS, if the little eline package can dissipate the same as to92lm
 
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#35
If some are interested in starting a groupbuy it's a lot of the real thing out there, Sanyo 2SC3503E and 2SA1381E
These are both SC and SA in E grade.
I would have started a groupbuy myself if freight cost wasnt so ******* expencive from here.

See here.

BTW: the min. quantity has changed from 925 to 1110 pcs.

Stein
 
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#36
@stinius,

looks like nobody is interested for a group buy. I would like to have my hands on them but no more than 50 of each. 🙁

Edit: Hmm, on the other hand it doesn't make sense. Digikey shipping rate for the slowest carrier (USPS) is around $50-60 bucks.
Also, when it comes to packages outside the EU dungeon, Croatian customs would charge me all the duties.
Btw, we have the highest VAT in Europe which is 25%.
 
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