Re: #qcxmini Ideal BPF Peak and 5v on coax center pin? #qcxmini

John Pagett G4YTJ


Don’t worry about the 5V on the coax centre pin. It comes from the output of IC3C (pin 8) - at least on the QCX+. It’s possible that Hans has used different pins on the mini, I haven’t checked, but the principle remains the same.

This output produces the alignment signal for setting up, but is attenuated by a 120k resistor (R 43). When the alignment signal is off the gate output sits at 5V but the 120k resistor will mean that you can connect a dummy load or antenna without issue.


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