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Yamaha 2SK77 vs Tokin 2SK180 - TempCo test
- Thread starter rottalpha
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- tokin sit yamaha sit
Acting all tough here but the secret is, I waited her to go out of the house before I pulled this off, and monitoring that tesla locator like a hawk to make sure I do not get caught on the act
What happened with all the Tex curves?
Nick has a habit of doing this.
Sorry. I thought I'd try to fix the contrast on them a bit so that you can't see my camera in the background but why bother.
Some curve tracer snaps of 3 different K77 ranks.
2SK77 AM 0.1A/div, 10V/div, 2V/step
2SK77 AM 0.5A/div, 2V/div, 1V/step
2SK77 BK Th 0.1A/div, 10V/div, 2V/step
2SK77 BK Th 0.5A/div,/2V div,/1V step
2SK77 CK 0.1A/div, 10V/div, 2V/step
2SK77 CK 0.5A/div, 2V/div, 1V/step
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Sorry. I thought I'd try to fix the contrast on them a bit so that you can't see my camera in the background but why bother.
Some curve tracer snaps of 3 different K77 ranks.
View attachment 3157114
2SK77 AM 0.1A/div, 10V/div, 2V/step
View attachment 3157117
2SK77 AM 0.5A/div, 2V/div, 1V/step
View attachment 3157119
2SK77 BK Th 0.1A/div, 10V/div, 2V/step
View attachment 3157121
2SK77 BK Th 0.5A/div,/2V div,/1V step
View attachment 3157123
2SK77 CK 0.1A/div, 10V/div, 2V/step
View attachment 3157127
2SK77 CK 0.5A/div, 2V/div, 1V/step
these ranks are consistent.
eg: AMs -> Vgs =12v (precisely at 12v) for 400mA @90v Vds
I have a couple of sets just like this with 12v Vgs or right around there
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It's nice when the operating point you're looking for falls right on the graticule crosshairs like that.
Yes it is
Coincidently I used the same rank for demonstration purpose, for a topic I will share soon.
Thanks. I had serious thoughts about posting it. Stay away from that curve tracer. It takes a fraction of a second to zap those vfets.
Souper video Pete!
And an interestingly understandable find with the gate leakage current/+TC on the bad AK (Audiokarma) ranked K77.
I'll be paying more attention to that from now on; I probably would have found a similar thing going on with the thermally intermittent CK that died on me while DC PS testing.
No, Im glad you did. I will NOT use that 575 to check the B-1's V's for sure .
Every time you do one of these videos your educating those of us who know a little about how V-fet's work, a little more on them. I greatly appreciate that
as I love learning more about them and therefore being much more cautious .
Athanasios
I aslo have the Leader 905 curve tracer .
I started my electronics interest with CRT Projectors that have HVPS that put out 30,000 volts . So I definitely am extremely careful around electricity.
The LVPS on that unit used 390 VDC to run the HVPS , I fused a screw driver to the case with that. Scared the **** out of me !!! lol
The most fun part was adjusting the tubes while the projector was on and all 30,000 volts and the 1000 VDC going into the tube and you can feel your hair on your arms tingling. one hand in my pocket at all times doing that .
The Tube's neck card .
Nashou
I started my electronics interest with CRT Projectors that have HVPS that put out 30,000 volts . So I definitely am extremely careful around electricity.
The LVPS on that unit used 390 VDC to run the HVPS , I fused a screw driver to the case with that. Scared the **** out of me !!!
lolThe most fun part was adjusting the tubes while the projector was on and all 30,000 volts and the 1000 VDC going into the tube and you can feel your hair on your arms tingling. one hand in my pocket at all times doing that .
The Tube's neck card .
Nashou
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IMHO the 905 is not quite as capable as the Heathkit when it comes to V-FET's ... but it's good enough for lots of other semiconductor testing. As always, YMMV.
Pete, I've been thinking about your explanation in your video on how to use the curve tracer offset control function. It looks like a great feature that I haven't tried yet on my 577 but I will the next time I look at a V-FET since as you say, it allows you to to get in close and not have to split hairs for the measurement so thanks for pointing that out!
Just curious though, can you explain why you offset the 0V curve to the operating point to take the measurement? Isn't the V-FET in cutoff at 0V? Instead, wouldn't it be the 2V curve where the V-FET is turned on that you offset for the measurement? I looked at the offset control explanation in the manual and it doesn't say much about how to use it ...
Also, when making the measurement, for better accuracy shouldn't you reposition the trace horizontally to start at 0?
Just curious though, can you explain why you offset the 0V curve to the operating point to take the measurement? Isn't the V-FET in cutoff at 0V? Instead, wouldn't it be the 2V curve where the V-FET is turned on that you offset for the measurement? I looked at the offset control explanation in the manual and it doesn't say much about how to use it ...
Also, when making the measurement, for better accuracy shouldn't you reposition the trace horizontally to start at 0?
Good questions.Pete, I've been thinking about your explanation in your video on how to use the curve tracer offset control function. It looks like a great feature that I haven't tried yet on my 577 but I will the next time I look at a V-FET since as you say, it allows you to to get in close and not have to split hairs for the measurement so thanks for pointing that out!
Just curious though, can you explain why you offset the 0V curve to the operating point to take the measurement? Isn't the V-FET in cutoff at 0V? Instead, wouldn't it be the 2V curve where the V-FET is turned on that you offset for the measurement? I looked at the offset control explanation in the manual and it doesn't say much about how to use it ...
Also, when making the measurement, for better accuracy shouldn't you reposition the trace horizontally to start at 0?
View attachment 3162889
It actually is positioned to start exactly at Zero. There ae some dark arrows in the 576 display that might give you the illusion I was not at zero.
If using the first step to measure then the offset would be offsite by another 2v (in this case), so it has to be the line at the origin. If using the first step in this case I would have not gotten to the 6x multiplier.
Another way to look at this, as in cross-checking to verify this method is that I used a vfet with a Vgs of ~12v at those conditions and we saw precisely where the 6th curve crossed the grid when the multiplier was set to Zero.
Then we moved the same vfet to a method that uses a digital readout and that also showed the same result.