so i finally finished putting together a MTR-3B kit over the past few weekends and honestly i was not expecting it to actually work on the first power up but it did, made a contact into ohio from pennsylvania on 40m running maybe 3 watts and i was pretty stoked about that. the whole thing just amazes me that you can do that with basically nothing.

anyway i do have some questions. im getting what sounds like a little bit of receiver hiss or maybe background noise that i didnt expect, not sure if thats just the nature of the radio or if i did something wrong in the build. also the battery situation is confusing me a little — right now im using a 3s lipo i had sitting around from an RC hobby thing and it seems to work but i dont know if thats the right call long term. anyone run these on lipo and had issues? and one more thing, whats a good way to get spotted without a phone or internet out in the field, i know SOTA activators manage it somehow but i havent figured that out yet.

congrats on the first contact, that ohio path on 40m is totally doable at 3w especially if conditions are halfway decent. the hiss you're hearing is probably just the receiver doing its thing — the MTR series isnt exactly known for having a super quiet front end, its a very stripped down design and that's kind of the tradeoff. if the noise goes away when you antenna is disconnected then its just band noise and you're fine. if its there regardless then maybe check your solder joints around the audio section, cold joints there can add some noise.

on the lipo question yeah people run them all the time, just keep an eye on the voltage and dont let it drop below about 3.5v per cell under load or you'll be stressing the cells. a simple cell checker you can get for a few bucks is worth having in your kit. 3s gives you around 11-12v fully charged which is fine for that radio.

for spotting without internet look into RBN — the reverse beacon network will spot you automatically when you call CQ on CW if anyone with a skimmer hears you. so you dont actually have to do anything except get on the air and call. thats how most SOTA folks get spotted when they're out of cell range.

oh man i went down the same rabbit hole last year, started with a rockmite and then ended up with a whole pile of QRP stuff. the lipo thing works but just be careful, i killed a cell once by running it too low because i got caught up in a pileup and forgot to check, now i just tape a little voltage alarm buzzer to the pack and it beeps at me when its getting low. like two dollars on amazon and it saved my battery more than once.

also if you get into SOTA the sotawatch site lets you self spot from a text message in some regions i think, might be worth looking into depending where you activate. welcome to the rabbit hole by the way, its all downhill from here in the best possible way