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Old 11th April 2014, 10:52 AM   #1
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Default 2sk246 bias problem

Hi
I use the pair 3sj103&2sk246 in the F5:
When I tray to bias , the 2sj103 bios normally, when I clock count the pot the current rise.
But when I try to bias the 2sk246 the max is 0.2A when the 2sj103 gives 1A.
I have many of this transistor and after replace the results is same.
thanks

Last edited by erez1012; 11th April 2014 at 12:47 PM.
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Old 11th April 2014, 11:01 AM   #2
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bios ?
do you want talk about bias ?
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Old 11th April 2014, 12:17 PM   #3
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It's best you approach these thing systematically.
Use the same dc supply voltage as shown in the f5 article.
Then measure important voltages eg Vgs etc and put them on this thread.

Others who take picture and use schematics with measured voltages written on the diagram tend to get quite a lot of help.
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Old 11th April 2014, 12:38 PM   #4
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it seems as matter of Jfet Idss

so , schematic please , so we know what to write
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Old 11th April 2014, 12:52 PM   #5
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hi
i remove the protaction transistor and r17,19,15.
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Old 11th April 2014, 01:30 PM   #6
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set both P1 and P2 to zero - confirm same measuring ZERO OHMS across R5 and R6

change R5 and R6 to 4K7

start biasing procedure - plenty of tutorials ( member 6L6 and others ) around
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Old 11th April 2014, 01:36 PM   #7
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thanks. i change the R5,R6 to 4K7.
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Old 11th April 2014, 01:48 PM   #8
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what ?

you will change ........ or you already change , prior to starting this thread ?
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Old 11th April 2014, 01:57 PM   #9
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no i will change and post the results.
sorry for my bed English
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Old 11th April 2014, 02:24 PM   #10
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You are completely changing the whole set up of the circuit.
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