Don't you need _very_ well matched JFETs
to ensure drain current balance in that circuit?
Could this be avoided by giving each JFET source
an independent primary and 330 ohm resistor,
then linking the "centre-tap" with the capacitor?
If you were making a differential amplifier for instrumentation
purposes, yes. But in this application you are making a pair of source
followers, and the amount of error in using an unmatched pair in such an
application would hardly be noticeable. However, if you want to go to the
extreme of precisely matching (meaning "very well") devices down to 0.01%
you may feel free to do so.
Your second suggestion would be sufficient to overcome the adversity of
using unmatched FETs if you feel that it's necessary to be that exact. I
had thought of doing so, but the application is not that demanding since the
load impedance presented by the 2N5109 as seen through the transformer is
quite high.
Chris
,----------------------. High Performance Mixers and
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\ _______,--------------' Chris Trask / N7ZWY
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