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Old 12th August 2009, 02:31 PM   #1
early is offline early  United Kingdom
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Join Date: Jun 2008
Default 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 .
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Old 12th August 2009, 02:48 PM   #2
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Join Date: Nov 2006
Location: Lyon
2SJ108 = 2SJ74
2SK370 = 2SK170

BL grade prefered

Have a look there, Spencer provides matched pair and quads :

Cheers !
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Old 12th August 2009, 03:46 PM   #3
early is offline early  United Kingdom
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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 .
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Old 12th August 2009, 03:57 PM   #4
h_a is offline h_a  Europe
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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
High Octane phono preamp Wiki
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Old 12th August 2009, 04:01 PM   #5
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Location: 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
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Old 20th August 2009, 07:34 AM   #6
early is offline early  United Kingdom
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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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