My experience with a 30m QCX? was exactly the same as Steve MW0KST. My unit as built had 2.5dB loss in the LPF and also too low a cutoff frequency when measured on a spectrum analyser, meaning that the filter roll-off was already a significant factor at 10.1-10.15MHz.
I replaced the two "blue blob" ceramic capacitors in the inner part of the PF and also took 1 turn off each of the three toroid coils in the LPF. Power output increased from less than 1W to around 2.5W with a 12V DC supply, which I'm happy with. Measuring the modified LPF on the spectrum analyser (and doing some modelling using RFSim99) convinced me that taking more than 1 turn off the coils would not give any further beneficial effect in my case.
These turquoise-blue blob capacitors do seem to be entirely unsuitable for use in the LPF as they appear to be low-Q/lossy - if you have these in the kit, my advice would be DO NOT use them - or if they've already been fitted, immediately replace them with higher-quality types (ceramics, polystyrene, SM or whatever - I used 160V polystyrene as that's what I had available).
73, Kevin ZL3KE
