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replacement fet

acdc90 6 months ago

Hello

i am repairing a UK made Amplifier

this is anilog and uses Fets as the finials

i have dual rails of 45v

the originial fets are 2SJ119 and 2SK414

the rest of amp is now going

i have taken the fets from good channel to prove i got it right

i have tried fitting IRFP240 and IRFP9240 as i had them on hand

which worked BUT draw too much idle current

I think the Gate cut off is why they didn't work

i find E14 have a better range of fets over RS

i dont want to get aliexpress or ebay

can some one sugest a better pair to use

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michaelkellett 6 months ago in reply to shabaz +1

As often happens I can't reply direct to the OP so must tag on after Shabaz The 2SJXXX and 2SKXXX series are lateral power MOSFETs, originally made by Hitachi. The IRF MOSFETs are vertical types with…

0 shabaz 6 months ago

You can still buy these. Looks like https://www.cricklewoodelectronics.com/ sell them, and they are in stock. Otherwise, you'd need to compare the datasheets to find an equivalent, because I doubt too many people know off the top of their heads what is a direct replacement, better or worse, for the particular use-case.
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0 michaelkellett 6 months ago in reply to shabaz

As often happens I can't reply direct to the OP so must tag on after Shabaz

The 2SJXXX and 2SKXXX series are lateral power MOSFETs, originally made by Hitachi. The IRF MOSFETs are vertical types with very different characteristics.

The original Hitachi parts had relatively high on resistance and were quite robust. The Id against Vgs curves are quite different so you can't swap in IRF parts and expect it to work.

There is a lot of material on the web which describes these (Hitachi) parts and how amplifiers can be made with them. You can design reasonable HiFi amplifiers with IRF parts but they will be different.

Check out here for more:

http://cordellaudio.com/poweramp/why_mosfets.shtml

MK
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0 acdc90 2 months ago in reply to michaelkellett

thankyou i have started looking at that web site
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