If a crystal IF filter is the heart of an SSB rig, then frequency mixers are its lungs. They either breath in RF from the antenna and convert the signal to an intermediate frequency, or they take the IF and exhale–“mix it down”–to audio (SSB) or (here’s where the metaphor breaks down) they “beat” it with the reproduced carrier coming from the BFO to make CW audible. Both are pretty-good tricks, and they’re accomplished with remarkably-simple circuits.

The circuit of a diode-ring mixer is simple, but making one with good balance, high isolation between inputs, and low-insertion loss is not trivial. It’s absolutely doable for a home-brewing Ham, but a wise person chooses his or her battles carefully. If you want a drop-in solution to save your efforts for other struggles, the Mini-Circuits ADE-1 series is a good choice. They’re surface-mount devices–not too hard to handle–but if you’d rather not then here’s a little board with the mixer already soldered in place and ready to mount in your rig.

Mini Circuits make a mind-boggling array of mixers, but the ADE-1s are inexpensive and unobtrusive. Mostly DIY RF offers three variants. The ADE-1+ is good from 500KHz to 500MHz and requires +7dBm of LO drive power. The ADE-1H covers the same frequency range, but it needs +17dBm of drive. Its virtue, though, is that is offers nearly twice the IP3 performance as the ADE-1+. The ADE-1L+ goes the other way: it needs only +3dBm of LO drive (useful for a low-power analog VFO), at the cost of poorer IP3 figures.

Be sure to take a look at the Mini-Circuits datasheets linked below for more information.