more jfet info

For the three and more legged things
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ed
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#1 more jfet info

Post by ed »

I would guess that those people interested in such things may already have seen this.

If not here is a link:
https://www.diyaudio.com/forums/pass-la ... ringe.html

**** you will likely need to login to diyaudio to read at the moment....I'm sure it will be on the firstwatt site before long ***
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JamesD
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#2 Re: more jfet info

Post by JamesD »

Hi Ed,

Thanks for referencing the article - interesting to see Nelson's measurements but I'm a little surprised by the text as I thought this was known already??? I first used J-Fets back in 1978 when a collegue at Thames TV introduced me to them by making a differential phono head amp with Fets that was flat to 5MHz - we tested it by passing a PAL colour TV signal through it with less that 2dB drop at 5MHz and to do this we used biasing above Idss to get the 75R driving requirement for co-ax video signal cabling. The linearity requirement for PAL is very demanding from 5Hz to 5MHz so audio was easy (This isn't really true as audio dynamic range is far greater than videos but videos bandwidth is far greater and distortion is critical for both...)

ciao

James
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