John
very good - I am interested in your results on this, and which ubitx version you have.?
on 12m you might notice 2 spurs on either side of the carrier about 5 MHz apart,? the v5 comes with a LPF similar to you have drawn already installed.? I tried one using SMT inductors on my v4 -- not much change -- not surprising since the spurs are close to carrier.? I did change R26 on mine, but I still have stock 2n3904 transistors (if I were bored I might see what better old stock transistors I might have for 45 MHz - but that might be an adventure).?
on your 12 and 10m readings you are mostly focused on harmonics of the RF output.? either your close-in spurs are good -- or you didn't notice them??
you could be a little confused as this LPF is described as filtering harmonics of 45 MHz.? one of those 2 spurs I mentioned seems to be 90 MHz - the LO frequency.? the other spur I think is the PA signal leaking back to the mixer, and mixing again. ?
with any changes you make in this part of the circuit - do see if you get any reduction of CW output power -- mine does a bunch on 40 and 80 meters. ?
73 Curt
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