B1 jfet help .

early · 12th August 2009, 03:31 PM

Hello all ,

I'm new around here and I'm in the process of ordering up bits to make up the B1 .

Now please forgive me if this is a stupid question but I'm new to playing with these new solid state thingies ( I've much more experience with valve circuits ) and am not that clued up on them .

Here in the UK I'm struggling to find 2SK370 fets in the usual places
RS , Farnell ect .

However Farnell have 2SK3702 is this the same / alternative ? .
Also I can get J310 is that a drop in replacement for 2SK370 or will the circuit need adapting .

Thanks in advance , e .

korben69 · 12th August 2009, 03:48 PM

2SJ108 = 2SJ74
2SK370 = 2SK170

BL grade prefered

Have a look there, Spencer provides matched pair and quads :
http://www.diyaudio.com/forums/showt...56#post1902356

Cheers !

early · 12th August 2009, 04:46 PM

Thanks Korben ,

I'm still confused , is a 2SK3702 a different grade of 2SK370 ? .

Anyway being the impatient type I've ordered both J310 and 2SK3702
It's not going to break the bank to try them .

Thanks for the link , but 100 of 'em is way too many for me .

Cheers , e .

h_a · 12th August 2009, 04:57 PM

Sorry for the (too) late reply!

2SK370 is a JFet made by Toshiba in a small package.
2SK3702 is a MosFet made by Sanyo and comes in a large package.
J310 is a JFet.

The 2SK3702 is not a replacment for the 2SK370; the J301 is a least a jfet, but unfortunately with a smaller voltage rating and smaller transconductance. I don't know the details of the B1, it might work (maybe modifications needed).

Sorry for the news, but I would recommend getting the original part, even if you have to order it from Dalbani or some other specialist for small signal parts.

Have fun, Hannes

korben69 · 12th August 2009, 05:01 PM

2SJ74 and 2SK170 are available in 3 different grades V, GR and BL.
Both are Toshiba JFet.
BL grade is prefered for B1.
Spencer delivers matched sets, there's no need to order 100 units...
Send him a mail for your request, he's very reliable

early · 20th August 2009, 08:34 AM

Thanks for the replies .

I have now built ( well breadboarded ) the B1 , and the J310 works a treat ! .

Just need to sort out some case work now .

12th August 2009, 03:31 PM	#1
early diyAudio Member Join Date: Jun 2008	B1 jfet help . Hello all , I'm new around here and I'm in the process of ordering up bits to make up the B1 . Now please forgive me if this is a stupid question but I'm new to playing with these new solid state thingies ( I've much more experience with valve circuits ) and am not that clued up on them . Here in the UK I'm struggling to find 2SK370 fets in the usual places RS , Farnell ect . However Farnell have 2SK3702 is this the same / alternative ? . Also I can get J310 is that a drop in replacement for 2SK370 or will the circuit need adapting . Thanks in advance , e .

12th August 2009, 04:57 PM	#4
h_a diyAudio Member Join Date: Sep 2006 Location: Graz, Austria	Sorry for the (too) late reply! 2SK370 is a JFet made by Toshiba in a small package. 2SK3702 is a MosFet made by Sanyo and comes in a large package. J310 is a JFet. The 2SK3702 is not a replacment for the 2SK370; the J301 is a least a jfet, but unfortunately with a smaller voltage rating and smaller transconductance. I don't know the details of the B1, it might work (maybe modifications needed). Sorry for the news, but I would recommend getting the original part, even if you have to order it from Dalbani or some other specialist for small signal parts. Have fun, Hannes __________________ fresh matched IRFP240/IRFP9240 fets \|\| AlephJ/JX-kits F5 transistor kits \|\| Burning Amp BA-1/2/3 transistor kits

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12th August 2009, 03:48 PM	#2
korben69 diyAudio Member Join Date: Nov 2006 Location: Near Lyon	2SJ108 = 2SJ74 2SK370 = 2SK170 BL grade prefered Have a look there, Spencer provides matched pair and quads : http://www.diyaudio.com/forums/showt...56#post1902356 Cheers !

12th August 2009, 04:46 PM	#3
early diyAudio Member Join Date: Jun 2008	Thanks Korben , I'm still confused , is a 2SK3702 a different grade of 2SK370 ? . Anyway being the impatient type I've ordered both J310 and 2SK3702 It's not going to break the bank to try them . Thanks for the link , but 100 of 'em is way too many for me . Cheers , e .

12th August 2009, 05:01 PM	#5
korben69 diyAudio Member Join Date: Nov 2006 Location: Near Lyon	2SJ74 and 2SK170 are available in 3 different grades V, GR and BL. Both are Toshiba JFet. BL grade is prefered for B1. Spencer delivers matched sets, there's no need to order 100 units... Send him a mail for your request, he's very reliable

20th August 2009, 08:34 AM	#6
early diyAudio Member Join Date: Jun 2008	Thanks for the replies . I have now built ( well breadboarded ) the B1 , and the J310 works a treat ! . Just need to sort out some case work now .

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