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Old 23rd February 2013, 12:57 AM   #201
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Originally Posted by Shiege View Post
If you do not find them in you lab I could have a look in mine and borrow you some. I think I am to busy and not experienced enough for audio applications ;-)
That's thoughtful, thanks. I haven't actually looked yet, so let's wait and see.
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Old 25th February 2013, 12:52 PM   #202
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I ran the Id up a little higher but I did not go as far as I wanted before I ran out of time... I made a few measurements up 20Vds and did not see much difference. This graph is with a .25 ohm Rs in the circuit (included in the Vds).
I have a question now for SemiSouthFan: In your paper "is it Semisouth?" you show a graph of Vgs vs Ids of 3 SS devices and a BJT I think. You elude to the device on the left (the lowest Vgsth) actually being out of spec but you say it shows the more triode like behaviour? I do not see this behaviour? Is it that my sample has a Higher than typ Vgsth? Thx
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Old 25th February 2013, 05:10 PM   #203
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I ran the Id up a little higher but I did not go as far as I wanted before I ran out of time... I made a few measurements up 20Vds and did not see much difference. This graph is with a .25 ohm Rs in the circuit (included in the Vds).
I have a question now for SemiSouthFan: In your paper "is it Semisouth?" you show a graph of Vgs vs Ids of 3 SS devices and a BJT I think. You elude to the device on the left (the lowest Vgsth) actually being out of spec but you say it shows the more triode like behaviour? I do not see this behaviour? Is it that my sample has a Higher than typ Vgsth? Thx
This device was out of spec because the threshold voltage was below 0.75 V; but I think it still blocked 1200 V at VGS = 0. And yes the output curves had more shape (lower drain resistance) than the typical R100 with threshold within the limits (0.75-1.25 V). I'll see if I can find it at home.

I think the curves you are seeing are typical for the specified threshold voltage range. I'm not sure why you have Rs in the circuit, as it will influence the shape of the curves you measure.
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Old 25th February 2013, 05:22 PM   #204
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As far as why I did some curves with an Rs in them. I did a standard style curve a few pages ago without any Rs. ZM suggested I add an Rs and I thought it would be interesting to see the linearization vs loss of gain. Effects of THD in these 2 configurations would have also been interesting but I am not set-up to do such tests at the moment. I suppose I can check my other devices and see if I have a low Vgs device similar to yours.
I'm also interested in looking at an R085 device as to me it sounds more promissing?
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Old 25th February 2013, 07:36 PM   #205
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As far as why I did some curves with an Rs in them. I did a standard style curve a few pages ago without any Rs. ZM suggested I add an Rs and I thought it would be interesting to see the linearization vs loss of gain. Effects of THD in these 2 configurations would have also been interesting but I am not set-up to do such tests at the moment. I suppose I can check my other devices and see if I have a low Vgs device similar to yours.
I'm also interested in looking at an R085 device as to me it sounds more promissing?
That's a good reason to add Rs, cause that's what it's supposed to do.

The output curves of the R085 I've been testing in the lab (and R045) have lots of curvature, so you may be right.
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Old 25th February 2013, 09:06 PM   #206
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I understand the Drain impeadance is much lower in R085! A characteristic similar to those Hollow State devices among others such as SITs
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Old 25th February 2013, 09:48 PM   #207
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I understand the Drain impeadance is much lower in R085! A characteristic similar to those Hollow State devices among others such as SITs
Yep
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Old 28th February 2013, 12:12 AM   #208
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Default What's the Buzz? Part I

I've been working on this for awhile. Time to shoot the engineer and post the article!

Attached is the first part in a three part series entitled "What's the Buzz?" It's my attempt to understand why you guys like the SemiSouth JFET so much. I can guess that some of you might think I could better use my time if I did less calculating and more building, but Jim and I are working on that omission. And, you can't take the professor out of me. I just can't help myself, I have to analyze this stuff to satisfy my curiosity.

As before, I hope you find it both worthwhile and entertaining to read. Let me know what you really think!
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Old 28th February 2013, 12:28 AM   #209
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How does it sound. It makes me wish my school years were not over. Excellent job prof.
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Old 28th February 2013, 01:11 AM   #210
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How does it sound. It makes me wish my school years were not over. Excellent job prof.
Thanks Dr. Mazzola for a great article and analyses therein.
buzzforb, and others. The last page of the article shows that Dr. Mazzola's Company "maintains inventory" of SemiSouth SIC JFETs and other specialty SemiSouth JFETs [maybe SIT?]. Great news.
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