so ive been wanting to build something from scratch for a while now and finally just dove in and built a simple direct conversion receiver for 40m. followed a design i found in an old QST article, wound my own toroids and everything. the thing does receive something — i can hear carriers and what sounds like SSB voices buried in noise but they're really hard to make out. gain seems way lower than i expected.

my local oscillator is running, i can verify that with my frequency counter, sitting right around 7.1 MHz. the detector is a diode ring i built on a little piece of perfboard. not sure if my problem is in the AF stage or the mixer or what. i didnt put a preamp in front of it because the article said it wasnt strictly necessary but maybe thats the issue. antenna is just a random wire off the back of my house, probably 30 feet or so. any thoughts on where to start poking around?

direct conversion receivers are kinda finicky about that stuff — the diode ring balance matters a lot more than people realize. if your diodes arent matched reasonably well you lose a chunk of conversion efficiency and the LO rejection goes to hell too. worth grabbing four diodes and checking them with a DMM at least for roughly similar forward voltage. also 30 feet of random wire going straight into a mixer is asking for trouble, there's no filtering happening and you're probably getting all kinds of junk in there. even a simple low pass filter before the mixer makes a noticeable difference on 40m. the AF amp side is worth checking too, what are you using there, just a single transistor stage or something like an LM386?

yeah i built something similar last winter and had basically the same problem. turned out my toroid winding for the input transformer was off — i had the phasing wrong and was losing like 6dB before the signal even got to the mixer. pulled it apart and rewound it and suddenly it was like someone turned the volume up. worth double checking how you wound that if you have one in there. also 40m during the day can be pretty dead depending on where you are, have you tried it in the evening when propagation opens up more, might just be a timing thing on top of everything else.