so ive been working on this for probably six months now, a single conversion superhet for 40m, IF at 455kHz using one of those old surplus transformers i got from a hamfest box lot like three years ago. the RF stage is a JFET, mixer is a diode ring i wound myself on a binocular core, and the BFO is just a colpitts off a 2N3904. its all point to point on a piece of copper clad, not manhattan exactly but kind of close.

anyway i got to the point where im scared to actually connect it to an antenna and the battery, partly because i spent so much time on it and dont want to see smoke, and partly because i genuinely dont know if my BFO is on the right side of the IF passband. i tuned the BFO trimmer to where it sounds like it should be in my head but i dont have a signal generator to check properly. anyone done this without test gear, like is there a way to sanity check the BFO offset by ear using a known signal on the band or something? also my IF transformer cans are tuned but i wasnt totally sure what i was doing there either, i just peaked them for noise which felt wrong but i couldve sworn i read that somewhere.

the whole thing is probably a mess but it actually looks pretty decent physically which counts for something i guess

peaking IF transformers for noise is actually a pretty standard old-school method when you dont have a sig gen, so you probably did that right. what you do is connect the antenna, put your ear to it metaphorically, and slowly rock those slugs until the background hiss peaks up. means the passband is aligned at least roughly. its not perfect alignment but it works well enough to get you on the air and you can always tweak later once youre actually hearing signals.

for the BFO, honestly the easiest way ive found without a generator is to tune in WWV on 10 MHz if your set reaches there, or find a strong AM broadcast and use it as a carrier reference. tune until the carrier gives you a nice low audio tone, maybe 500-800 Hz or whatever pitch sounds natural for SSB, and thats close enough. if youre getting a high-pitched squeal instead of a clean zero-beat you're probably on the wrong sideband, just flip the BFO trimmer past zero beat to the other side. takes some fiddling but honestly your ears are decent test equipment for this. good luck, these scratch builds are worth it when they finally sing.

man i want to see pictures of this thing when youre done. im in the middle of a similar project, direct conversion on 20m, much simpler obviously but still. the point to point wiring on copper clad approach is something i keep going back to because etching boards feels like too much commitment when im still changing stuff every other day.

one thing i ran into with my diode ring mixer was getting a ground loop hum i couldnt shake for like two weeks, turned out one of my winding connections wasnt actually making contact, just touching. might be worth going over all your transformer joints with a meter before you power up just in case. probably not your issue but it drove me absolutely nuts and wouldve been a lot easier to catch early.