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JFETs from Linear Systems
JFETs from Linear Systems
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Old 5th April 2017, 06:42 PM   #81
jfazende is offline jfazende  United States
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Join Date: Apr 2017
I have not been able to find a 2SK99 data sheet. That has been one of my problems finding a replacement.
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Old 5th April 2017, 07:13 PM   #82
jfazende is offline jfazende  United States
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Join Date: Apr 2017
Quote:
Originally Posted by AndrewT View Post
Looks like the FETs are operating @ ~ 1.7mA each.
An Idss > 3mA maybe 4mA to 5mA would do.
Check the sk99 datasheet and see what the gm is at that 1.7mA Id
Then look for a device that has similar gm at the same current.
I have not been able to find a 2SK99 data sheet, so I don't know what the gm is.
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Old 16th May 2017, 04:50 PM   #83
jfazende is offline jfazende  United States
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AndrewT - I'm really struggling to find an equivalent to the 2SK99A. A member of different forum gave the following K99A specs:
VGSS -25V
IG 10mA
PD 100mW x2
IDss 1.5ma to 20ma
gm 80mOhm min (VDS=10V f-1kHz) that's a problem, usually such double FET in same package gives a MIN of 15mOhm not 80...
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Old 16th May 2017, 04:54 PM   #84
labjr is offline labjr  United States
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Location: MA
Are there any equivalent JFETs in an SMD package? I'm wondering what would a manufacturer use if they didn't already have a stockpile?
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Old 16th May 2017, 05:01 PM   #85
jfazende is offline jfazende  United States
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Join Date: Apr 2017
The 2SK99A is used the the first stage of the power amp in a vintage Yamaha CR-3020 receiver. Already contacted Yamaha, they didn't have any stockpiled parts or equivalents. Their only suggestion was to search online forums such as this one and eBay. :-(
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Old 16th May 2017, 05:12 PM   #86
AndrewT is offline AndrewT  Scotland
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Join Date: Jul 2004
Location: Scottish Borders
I don't follow his spec.
Vgss is not given by Onsemi, Linear and Toshiba
Vgss(off) is used by Fairchild
gm = 80milli-mhos (mS) is exceptionally high. I think that is a mistake.
Based on those two parts of his spec, I'm inclined to not use any of it.
__________________
regards Andrew T.
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Old 16th May 2017, 05:26 PM   #87
jfazende is offline jfazende  United States
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Join Date: Apr 2017
I have tried matched pairs of 2SK170BL's from two different supposidly reliable sources with no luck. I have received some LSK170's Grade B from DIYAudio store. Haven't tried them yet, not sure Grade B is what I need.
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Old 8th September 2017, 05:13 AM   #88
r_jik45 is offline r_jik45  Japan
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Location: Jpn, Fr
Hi,
I got lost with the specs and might have missed the info...
What is the recommended grade of LSK170 for the "Mezmerize B1 Buffer"?
Thanks!
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Old 8th September 2017, 06:38 AM   #89
r_jik45 is offline r_jik45  Japan
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Join Date: May 2005
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Ok.... B grade according to one of Salas' posts

Last edited by r_jik45; 8th September 2017 at 06:47 AM.
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