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SouthSemi modified F2J Clone

Posted 7th January 2012 at 09:13 AM by Tea-Bag
Updated 21st November 2010 at 12:46 PM by Tea-Bag

This last weekend I replaced the IRFP240 in my F2 Clone with the R100 SouthSemi Power-JFET.

tubes-guy used psychic powers to control my mind and force me to do it.

The bias dropped off the bat. I re-biased and gave it an A-B listen to the standard channel. Seemed to be a bit 'cleaner' sounding the the default channel.

Nelson has recommended the following changes to the circuit, which I hope to implement soon. I will be re-wiring these on Peter Daniels boards.
The Peter Daniel boards are still available I believe.

Papa sayz...

The F2's that I have updated with the JFETs need the
following changes:

R6 = 47k (changed to 8.2K of FW Site)

C1 = 10 uF

Z1 removed

The potentiometer must be re-adjusted for minimum
distortion at 4.5 watts (symmetric clipping) and readjusted
after an hour.

The distortion results are typically a reduction from about 1%
at 1 watt to .3% at 1 watt.

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  1. Old Comment
    alazira's Avatar
    Hi Teabag,
    Is that a keratherm red in the picture? If so, it does not need any goo.
    Posted 16th January 2012 at 11:19 PM by alazira alazira is offline
  2. Old Comment
    did you made your tests with a R6=47K?
    I need about 50K of input impedence and I'd like to know if you found any difference with the different values of R6.
    I bought the R100 from you and may be mine (same batch?) may have the same gate leakage current of yours.
    Posted 25th January 2013 at 01:43 PM by guglielmope guglielmope is offline
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