Christopher Lopez

so ive been working on this 40m direct conversion receiver for the past few weeks, pretty standard NE602 front end into an LM386 audio stage, nothing fancy. got it all wired up on a piece of copper clad with ugly construction and honestly the RF performance is better than i expected — im hearing stations just fine, selectivity is what it is with a DC receiver but thats fine. the problem is theres this constant 60hz hum in the audio and i cannot for the life of me figure out where its coming from. ive got it running off a wall wart supply that i thought was clean enough, measured the ripple on my scope and its pretty minimal, maybe 20-30mV which shouldnt be causing this. tried running it off a 9v battery and the hum drops way down but doesnt completely go away. so clearly part of it is the supply but something else is going on too. the audio amp section is probably the culprit honestly, the LM386 is notorious for picking up garbage if you dont lay it out carefully and im not sure my bypass caps are where they should be. i have a 10uf on pin 6 and a .047 on pin 7 but maybe i need more. anyone dealt with this before with the 386

same boat as you like six months ago lol. i just drilled hamstudy until i was consistently hitting 85% or above and then went and took the test. passed no problem. the feed line and impedance questions look scary but theres really only like a handful of them and once you see the pattern in the answers it clicks 40m was the first band i got on after upgrading, borrowed a friends dipole and just listened for a few days before i even tried transmitting. that actually helped a lot tbh

so ive been licensed for about 4 months now (got my tech in the spring, studying for general) and i keep hearing people talk about nets like theyre this regular thing everyone does but i honestly still dont fully understand the process. like i know you tune to the frequency and wait for the net control to call for check-ins but then what, do you just say your callsign and thats it? or is there more to it? i found a net on 147.315 that meets on tuesday nights and i listened for a couple weeks but i was too nervous to actually check in. the net control guy seems really friendly but it goes pretty fast and i didnt want to mess anything up. is there like a standard format i should know before i try? also i saw something about a special event station for a local hamfest coming up and wondering if those work differently than a regular net check-in

88 means love and kisses lol, you mostly hear that one on 2m between people who know each other well. kind of a thing mostly between couples on the radio which is either cute or cringe depending on who you ask. one thing that confused me when i started was QSY, which just means change frequency. so if someone says lets QSY up 10 they want to move the contact 10 khz up. seemed obvious in hindsight but i had no idea for the longest time and just follwed whoever i was talking to without really understanding why we were moving

so ive been wanting to do this for probably two years now and last weekend i finally just did it. built a bitx40 from scratch (well sort of, the kit makes it pretty approachable) and took it out to the state park about 20 minutes from my house with a end-fed halfwave and a little tripod mast thing i cobbled together from electrical conduit. ran about 7 watts into the antenna, which isnt exactly QRP by the strict definition i guess but close enough. made 6 contacts in about 2.5 hours including one guy in kansas which blew my mind a little because im in virginia and the conditions werent even that great according to the DX cluster when i got home. the whole setup fit in a backpack and ran off a 3ah lipo i had from an old RC car project. honestly the efficiency thing is kind of addictive once you get into it — like i keep thinking about how i squeezed that kansas contact out of 7 watts and a wire in a tree and it feels way more satisfying than just cranking up power on my base station. anyway wondering if anyone else here does a lot of SOTA or POTA type stuff with homebrewed rigs? curious what you guys are running for antennas when you go portable, especially if you're trying to keep weight down.

honest question and maybe this is obvious but how do you even know where to transmit on split if the DX just says "up" and doesnt give a specific frequency. i always end up guessing and i feel like im just landing in a random spot

this sounds a lot like the drill we did a couple years ago lol. the over-talking was our biggest problem too. i think people just panic a little even when they know its fake and forget everything they know about proper procedure. one thing our group started doing was requiring everyone to actually review ICS-213 message format before drills and we designated one person per shelter as the only one allowed to key up unless it was a genuine emergency within the scenario. cut the chaos down a lot. also honestly the debrief thing is huge, i feel like thats where the real learning happens and a lot of groups just skip it or do five minutes and call it done.

i did my second activation last month and also used HAMRS, it gets easier once you get a rhythm going but yeah the first time is a lot to manage at once. i actually just say the callsign out loud while i type it which sounds weird but it helps me not make mistakes. also if you havent already set up the quick exchange fields in the app before you leave home so you're not messing with settings while trying to call CQ.

so ive been a general for about 3 years now and ive been going back and forth on whether to bother with the extra. i know a lot of people just use the question pool and memorize their way through it but some of the stuff in there like the filter theory and the transmission line equations honestly looks like stuff i should probably actually understand at some point anyway my main thing is i mostly do HF, some SSB on 40 and 20, occasional digital. i dont really have a burning need for the extra HF allocations right now but i keep seeing those little slices of 40m and 80m that i cant use and it bugs me a little. is the theory in the extra actually useful day to day or is it just license exam stuff that you never think about again once youre done also how hard is it really compared to general, that jump felt pretty significant when i took it

yeah the board revision thing is real, i burned like two hours comparing my unit to some youtube video before realizing the guy had an older version. the diode locations are close but not identical and you definitely dont want to lift the wrong pad on that board. on the deviation question — i did mess with that on mine. theres a service menu you can get into, i think its hold the a/b button during powerup or something like that, been a while. there are pots on the board too but the menu approach is a lot less scary. mine was set conservatively from the factory and bumping it a little made a noticeable difference on the local machine. just dont go overboard or youll start getting complaints about overdeviation which is worse than sounding a bit thin.

yeah what he said basically. i went RTL -> HackRF -> RSP2 and the jump from hackrf to sdrplay felt bigger than rtl to hackrf did on HF. the RSP2 has the extra antenna ports which i use for a separate loop antenna on MW/LW but for just HF the RSP1C is probably fine and saves you some money. WSPR decoding with it and WSJT-X or even just fldigi works pretty painlessly once you sort the virtual audio cable stuff out. that part is always kind of annoying no matter what radio you use tbh

yeah the LM386 is notorious for picking up junk when the layout isnt tight. at 46dB gain that thing will amplify basically everything including stuff you dont want. first thing id try is keeping the input lead as short as absolutely possible and make sure you've got a cap right at pin 6 to ground, like physically right there on the chip not a few inches away. also a 10 ohm resistor in series between pin 5 and your output cap is kind of a standard trick to tame some of the instability, lot of the app notes mention it but people skip it. the wobbling hum you're describing actually sounds like it could be microphonics on the breadboard if you're on spring contacts. those things are terrible for RF builds, any vibration or even air movement can modulate stuff in weird ways. if you can solder even a rough ugly deadbug version of the audio stage and compare that tells you a lot.

yeah i had the exact same problem when i first got my uv5r lol, turns out i had the offset wrong the whole time. spent like two days thinking the repeater was broken or something. definitely check what the previous reply said about the offset, that's almost certainly it