Best source or replacement for KTA1700/KTC2800 transistors? - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State
Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Solid State Talk all about solid state amplification.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 27th September 2011, 12:01 AM   #1
Legis is offline Legis  Finland
diyAudio Member
 
Legis's Avatar
 
Join Date: Dec 2009
Default Best source or replacement for KTA1700/KTC2800 transistors?

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

Last edited by Legis; 27th September 2011 at 12:26 AM.
  Reply With Quote
Old 27th September 2011, 05:54 AM   #2
sajti is offline sajti  Hungary
diyAudio Member
 
Join Date: Apr 2003
Location: Százhalombatta, Hungary
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
  Reply With Quote
Old 27th September 2011, 10:17 AM   #3
CBS240 is offline CBS240  United States
diyAudio Member
 
CBS240's Avatar
 
Join Date: Aug 2005
Location: K-town
KSC2690A looks similar. It is TO-126 without a metal pad, cheap and plentiful. (at least here)
__________________
All the trouble I've ever been in started out as fun......
  Reply With Quote
Old 27th September 2011, 12:03 PM   #4
Legis is offline Legis  Finland
diyAudio Member
 
Legis's Avatar
 
Join Date: Dec 2009
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

Last edited by Legis; 27th September 2011 at 12:06 PM.
  Reply With Quote
Old 27th September 2011, 03:11 PM   #5
Account disabled at member's request
 
Join Date: May 2006
Quote:
Originally Posted by Legis View Post
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.
  Reply With Quote
Old 27th September 2011, 06:35 PM   #6
Legis is offline Legis  Finland
diyAudio Member
 
Legis's Avatar
 
Join Date: Dec 2009
Quote:
Originally Posted by homemodder View Post
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
  Reply With Quote
Old 28th September 2011, 01:23 PM   #7
Account disabled at member's request
 
Join Date: May 2006
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.
  Reply With Quote
Old 28th September 2011, 01:25 PM   #8
Legis is offline Legis  Finland
diyAudio Member
 
Legis's Avatar
 
Join Date: Dec 2009
I already ordered them from Mouser .
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
1" MDF sorce? nelsondog Multi-Way 5 22nd July 2011 09:52 AM
Transistor replacement grandville45 Parts 30 1st April 2010 06:50 PM
transistor replacement xcicc Solid State 0 16th August 2008 11:05 AM
Transistor Replacement portlandlay Solid State 26 14th December 2005 08:46 PM
Transistor replacement Mlaen Solid State 3 18th February 2005 12:00 PM


New To Site? Need Help?

All times are GMT. The time now is 08:59 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki