You're plenty cool to be digging into this stuff so deeply.
Xc is capacitive reactance. ?
Which is to say that Dexter thinks there's too much capacitance somewhere.
But could be lots of reasons for power out to drop as frequency rises.
I'm still betting on just a bad layout around the IRF510.
Capacitance could certainly play a role there.
Try this:
Remove power from the IRF510 drain by unhooking PA-PWR1.
Now measure the RF voltage at the IRF510 gate while attempting to transmit
using a scope or perhaps just a diode RF probe and DVM.
If that RF voltage remains roughly the same at 20m as it is at 40m,
then the issue is in the board layout right there at the IRF510.
The original Bitx was for 20m, so we know this can be made to work properly.
With the IRF510 drain not powered we are no longer concerned about IRF510's miller capacitance,
or outside coupling from drain to gate, or parasitic oscillations.
The primary load presented to T6 is now just the 47 ohms at R150 into the AC ground provided by C151.
I think.
Jerry, KE7ER
?
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On Mon, Nov 13, 2017 at 03:20 pm, Ryan Flowers wrote:
I am not cool enough to know what Xc is
