but the RF sweeps for 80m & 40m don’t look like low pass filters. 20m looks ok
The LPFs will not normally affect the trace very much, their cutoff will just be beginning at the right. Mostly it is the BPF you see. As you say 20m looks OK. I'm not sure about the others, the pictures I've seen from v3 QDXs often look worse than the v1 traces I've seen and in the manual. Some have tried peaking them. The real test is how it receives, whether you see a drop in noise when the antenna is disconnected. (Not easy to see in WSJT-X).
