OK. That sounds good. I would now try the bias procedure.
Start at page 8 (Adjust P1 for T16....):
http://www.firstwatt.com/pdf/art_diy_sony_vfet.pdf
Start at page 8 (Adjust P1 for T16....):
http://www.firstwatt.com/pdf/art_diy_sony_vfet.pdf
After I changed the FQP3n0 and FQP3P30 from the BOM by matched 2SJ313 an 2SK2013
my problems are gone!
The voltage test point are fine. my problem right now is the vgs wrote
on one of the Sony vfet pair. One pair are readable 9.9 but the second pair I can just identify the 9, the second digit can be 1 4 7 or 9 .
I don't know whom to ask !
my problems are gone!
The voltage test point are fine. my problem right now is the vgs wrote
on one of the Sony vfet pair. One pair are readable 9.9 but the second pair I can just identify the 9, the second digit can be 1 4 7 or 9 .
I don't know whom to ask !
If it's actually 9.1 and you pretend it's 10 and set the initial bias voltage
at 11, all that should happen is you will have to turn the bias pots more
to get current to flow during your installing vfet and adjustment procedure.
Since the vfet conducts more current as you decrease the bias voltage,
the idea of setting the initial bias voltage based the measured value of
the vfet is to make sure the current is low. If you know your parts are
9.X then setting the voltage at 11 is safe.
I took to much time writing my post and all have been lost!
we have similar values in g-t6 g-t8 and I changed r15 r16 to 46.4k but it's perhaps not necessary!
I would check again the resistors perhaps a 47.5k 47.5 has been inverted if not check the values of the trimers two are 500 ohms and two are 5k ohms. check if they are fully turned
we have similar values in g-t6 g-t8 and I changed r15 r16 to 46.4k but it's perhaps not necessary!
I would check again the resistors perhaps a 47.5k 47.5 has been inverted if not check the values of the trimers two are 500 ohms and two are 5k ohms. check if they are fully turned
Hello VFET Builders:
I am in the process of getting all of the parts together for my VFET build. A couple of questions. I just read if the MOSFETS I purchased are from Fairchild, I should have increased P3/P4 to 1K ohms. I ordered 500 ohm pots, and the MOSFETS are from ON Semiconductor, which Fairchild is now part of. Should I reorder 1K pots to avoid difficulties when biasing? Is this something that effects some builds and not others?
Secondly, my VFETS have the following Vgs ratings:
2SJ28: 9.6 V 2SK82: 10.3 V
Are these considered a "close enough match" and knowing these values seem somewhat higher than what others have posted, are there any part value changes I should consider before soldering? Thanks in advance.
Steve
I am in the process of getting all of the parts together for my VFET build. A couple of questions. I just read if the MOSFETS I purchased are from Fairchild, I should have increased P3/P4 to 1K ohms. I ordered 500 ohm pots, and the MOSFETS are from ON Semiconductor, which Fairchild is now part of. Should I reorder 1K pots to avoid difficulties when biasing? Is this something that effects some builds and not others?
Secondly, my VFETS have the following Vgs ratings:
2SJ28: 9.6 V 2SK82: 10.3 V
Are these considered a "close enough match" and knowing these values seem somewhat higher than what others have posted, are there any part value changes I should consider before soldering? Thanks in advance.
Steve
Bridging for Monobloks
Hi to all, I plan to convert two amp kits to monoblocks by bridging operation ( I need more power for my Quad ESL63), I’ve acquired two Jensen JT-123-SS transformers ( like the ones in First Watt F6).
I’d like an advice on the proper placement of the trans’ in the circuit. The more simple will be on the input’ or shell I place them after the Jfet transistor (2sk170’ 2sj74) like in the F6 circuit?
Thanks
Hi to all, I plan to convert two amp kits to monoblocks by bridging operation ( I need more power for my Quad ESL63), I’ve acquired two Jensen JT-123-SS transformers ( like the ones in First Watt F6).
I’d like an advice on the proper placement of the trans’ in the circuit. The more simple will be on the input’ or shell I place them after the Jfet transistor (2sk170’ 2sj74) like in the F6 circuit?
Thanks
