so i finally pulled the trigger on one of those QMX+ kits after reading about it here for months. took me about two weekends to build it, had to reflow a couple solder joints that were giving me grief on the PA section but eventually got it transmitting. fired it up last night on 40m with my endfed and honestly i was shocked - made contact with a guy in ohio and im sitting in vermont running maybe 4 watts. didnt even expect to get out of the state.

anyway now im kind of obsessed with the whole QRP thing. i keep reading about guys doing sota activations and running FT8 off a battery pack for hours and im thinking thats what i want to do this summer. my question is more about antennas i guess - like is a linked dipole really worth the hassle over just bringing the endfed and an antenna tuner? i feel like the weight difference cant be that dramatic but everyone i talk to has strong opinions about it. also curious what batteries people are actually using in the field, the whole LiFePO4 vs regular lithium stuff is confusing me a little bit.

congrats on the first contact, that ohio to vermont path on 40m with 4 watts is actually really solid, especially if conditions werent great. the QMX is a nice little rig once you get past the build gremlins.

on the antenna question - honestly both work and you'll get people going to the mat for either one. i use a linked dipole for SOTA because i like not needing a tuner, one less thing to fail or drain the battery, and you can cut it pretty resonant for whatever band youre activating on. but ive also seen guys haul an endfed with a tiny tuner and do just fine. weight difference is maybe a couple hundred grams which doesnt sound like much until youre on mile 6 of a trail. for the battery stuff, just go LiFePO4 and dont look back - they're safer than regular lithium, hold voltage flatter through the discharge curve which matters for your finals, and they last forever. bioenno makes decent packs that arent too spendy.

im in almost the exact same spot as you lol, built a kit last fall and now i cant stop thinking about portable ops. i went with a regular lithium battery pack at first (one of those usb power banks with a dc cable) and it worked okay but the voltage regulation was a little sketchy and i think it was current limiting on me during transmit. switched to a small LiFePO4 and the difference was noticeable. probably placebo but i swear my audio reports got better too.

havent tried a linked dipole yet, still just using a random wire with a tuner and it gets the job done for now. maybe next project