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Beast with 1000 JFETs redux ?
Beast with 1000 JFETs redux ?
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Old Yesterday, 10:09 PM   #181
woofertester is offline woofertester  United States
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Join Date: Jun 2011
Thank you Biosonar for that info. It helps enormously.

I have thought that the J113/J175 version should have source resistors for power dissipation reduction. Now I will start a PCB for that configuration.

While we are talking about the J113, my datasheet shows gate at the left-most pin. The actual JFET has gate at the right-most pin. What is the deal with that?

For Idss, my J113 devices are all between 14mA and 28mA. I have tested hundreds. I bought a bag of 1000. Slowly working my way through them.

My J175 devices are between 20mA and 24mA. I have tested 100. More are on the way.

My assertion is that the combined Idss of each 1/2 of the buffer must match. The parallel buffer elements are all connected at the output.

So, there will be a PCB for un-degenerated FJETs like the J270 and 2SK304. That pcb is on the way to me. There will be a pcb for degenerated JFETs like the J113 and J175.
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Old Today, 12:00 AM   #182
Biosonar is offline Biosonar  United States
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Join Date: May 2005
Location: Pennsylvania
Here is another possibility for CCS mini-beast using the Toshiba 2Sk209 GB jfet. This design was suggested by Wayne from Pass Labs. Remove R4, R5 and add a gate resistor to the input:
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Old Today, 12:20 AM   #183
woofertester is offline woofertester  United States
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Join Date: Jun 2011
Quote:
Originally Posted by Biosonar View Post
Here is another possibility for CCS mini-beast using the Toshiba 2Sk209 GB jfet. This design was suggested by Wayne from Pass Labs. Remove R4, R5 and add a gate resistor to the input:
I agree that a 2SK209/2SK208/2SK2145 massive B1 is a great idea. The trough-hole version is first on my list to build. The surface mount version for me will have to be assembled at a contract manufacturer.

Rochester has good candidates for through-hole JFETs. I have ordered some to evaluate. I will also build J113/J175 through-hole versions.
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