A diode ring mixer is built and tested. The design consists of two transformers and four diodes in a ring configuration. The device has three ports, one for the local oscillator (LO), one for the intermediate frequency (IF), and one for the radio frequency (RF). Being a passive device, the mixer operates without need for any external power. Testing was performed using a function generators and a TinySA spectrum analyzer.

Schematic

Schematic

Function Generator

I recently acquired a second-hand Siglent SDG 1032X Function generator from the Huntsville Hamfest for a very good price. It works great, but is missing a handle. I don't need one of those anyway. The frequency seems to be a little off, but I plan to rememdy this by getting a GPSDO 10 MHz reference. I figured that this would be a great tool to test my mixer with, especially since it has two output channels that can be use for the LO and IF inputs.

Siglent SDG 1032X Function Generator

Siglent SDG 1032X Function Generator