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GB for F6 Convertible Clone boards

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#361
Thank you for the reply Tea-Bag. I've been steered to the F5X thread by ZM but my google-fu hasn't been quite up to finding the document as yet. I'll get there eventually. I was chasing it to see how to go about degenerating slightly differing idss jfets to get a closer match. The K parts I have are 8.2mA and the closest match I have is J 7.6mA; so given your PCB is built for fixed degeneration I had thought to find a 'best' match degeneration point, and hopefully understand why!

Actually, on degeneration, why was the value of 0R56 (as oppsed to 0R47 or 1R as two other examples in the F6 thread) for the upper MosFet source resistor decided upon? Again, I ask for understandings sake as I'll be using cree MOSFET's (for fun and learning) and being that they're different parts to the IRFP240's I wonder if the source resistors need to be different? So I hope to understand why the difference in 'upper' (r13) and 'lower' (r14) resistance values as a default and what changing them achieves?

I might re-read the F6 article again... 🙂
 
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#371
Hi Mike,

I have finally got my hands on the boards)). I have two questions:

Which values did you use for R13 and R14. I can see that build thread suggests 10k

"R13*10K-15K (This is a current limiter resistor for the LED, it sets the brightness. I wouldn’t use anything less than 4.7K ohm. )'


, while the schematics are saying R1. Which is slightly different, which values did you use I your build?

I guess the diyaudio boards are using different notation.

And another question is when Q3B and Q4B should be used?

Thanks,

Oleg




Sent from my ONE A2003 using Tapatalk
 
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#372
What parts are you building with SemiSouth or IRF240? The Q,4B are for use with 2SK and 2SJ GR, where two pairs can make up the appropriate IDSS.


aradan said:
Hi Mike,

I have finally got my hands on the boards)). I have two questions:

Which values did you use for R13 and R14. I can see that build thread suggests 10k

"R13*10K-15K (This is a current limiter resistor for the LED, it sets the brightness. I wouldn’t use anything less than 4.7K ohm. )'


, while the schematics are saying R1. Which is slightly different, which values did you use I your build?

I guess the diyaudio boards are using different notation.

And another question is when Q3B and Q4B should be used?

Thanks,

Oleg




Sent from my ONE A2003 using Tapatalk
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