Re: Pushing the QCX (T1 question) #qcx

Alan G4ZFQ

;-)   I think a narrow BPF improves the performance.

Yes, I do not dispute that. But may I suggest the difference would not usually be noticed without careful comparison.

I would suggest isolating IC3 pin 3 with a capacitor.
It won't work... if you capacitatively couple IC3 pin 3 to the PA gate, then the peak-peak squarewave will be 5V BUT, it will be centered on 0V.
Oh yes, I see...
But it seems there have been a couple of cases where PA device failure has resulted in 12V being sent back through IC3. One of those affected have reported failure of the Si5351 and another has said IC2 required replacing.
If that really is the case then I'm wondering how to buffer IC3 to avoid this rare occurrence.

73 Alan G4ZFQ

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