Best source or replacement for KTA1700/KTC2800 transistors?

[Legis]

Hi, does anybody know a source for the KTA1700/KTC2800? I have not found any.

What transistor would be best and most readily available alternative to replace them, what are the most important values that should be matched closely? Would for example Hitachi 2SD669A (complementary is 2SB649/A) be good replacement, or would they be even better than the original part?

edit. or would these Toshibas be good replacements?: http://www.toshiba.com/taec/componen...nc/66/7654.pdf

Thanks!

Legis

[sajti]

HI,

the 2SC5171/2SA1930 would be OK if you not use higher power supply, than +/-50-55V, and the different case, and pinout is no problem.

Sajti

[CBS240]

KSC2690A looks similar. It is TO-126 without a metal pad, cheap and plentiful. (at least here)

[Legis]

Hi,

thanks for the answers.

The main power supply for power transistors is +/-58V. Predirivers (2SA1208/2SC2910) and the mentioned KTA1700/KTC2800sare maybe in +/- 64V supply, at least the predrivers are. The VAS is supposed to be Darlington with C dominant pole. The circuit is somewhat complex for for a beginner to make sense of.

Thanks, KSC2690A does look similar except little lower Ic. How's this one, 2SA1249/2SC3117 ? It has Same Ic and very good gain linearity, although gain is higher. Does this matter?

It's unclear to me what changes if the DC current gain is somewhat higher; the gain of the amp goes up perhaps (or the DC bias current and it has to be set accordingly)? Then what if the Ic is lower, what does it change (is it related the maximum bias current?)?

I think I will keep the same pinout and the casing the same as original part, it makes things easier.

Regards,

Legis

[homemodder]

Originally Posted by Legis

Hi,

thanks for the answers.

The main power supply for power transistors is +/-58V. Predirivers (2SA1208/2SC2910) and the mentioned KTA1700/KTC2800sare maybe in +/- 64V supply, at least the predrivers are. The VAS is supposed to be Darlington with C dominant pole. The circuit is somewhat complex for for a beginner to make sense of.

Thanks, KSC2690A does look similar except little lower Ic. How's this one, 2SA1249/2SC3117 ? It has Same Ic and very good gain linearity, although gain is higher. Does this matter?

It's unclear to me what changes if the DC current gain is somewhat higher; the gain of the amp goes up perhaps (or the DC bias current and it has to be set accordingly)? Then what if the Ic is lower, what does it change (is it related the maximum bias current?)?

I think I will keep the same pinout and the casing the same as original part, it makes things easier.

Regards,

Legis

What you should have a close look at here is the SOA graphs. The SOA for 2sa1249 is much lower than the fairchilds and even that toshiba pair is a bit frail, compaired to the original. To be on the safe side either use the Fairchilds (the 160V version) or the more robust toshiba pair 2sa1837/2sc4793.

[Legis]

Originally Posted by homemodder

What you should have a close look at here is the SOA graphs. The SOA for 2sa1249 is much lower than the fairchilds and even that toshiba pair is a bit frail, compaired to the original. To be on the safe side either use the Fairchilds (the 160V version) or the more robust toshiba pair 2sa1837/2sc4793.

So if I want to keep the same casing and be on safe side, I should get these: KSA1220A and KSC2690A? Does anybody know a good source for those that has reasonable shipping cost (to Europe)?

-Legis

[homemodder]

Europe is riddled with companies selling fakes and cheap chinese second source parts which dont perform to spec, i tend to source from usa but others here might know of reliable sources in europe. It will be easier to find 2sa1837 and compl in europe though.

[Legis]

I already ordered them from Mouser .