Your eyes and ears. If a circuit isn't working, the DMM tells you where the voltage stopped flowing.
Take a length of thin insulated wire. Use an online "Dipole Calculator" to find the length for the frequency you want to hear (e.g., 14.2 MHz for Ham Radio). String it up as high as possible between two trees. Radio and Electronics Cookbook
Avoid the cheap "fire sticks" that plug directly into the wall. A station that lets you dial in 350°C (660°F) will save your components from melting. Your eyes and ears
A long wire antenna (20+ feet) and a high-impedance earpiece. but with a bad antenna
You can have the most expensive radio in the world, but with a bad antenna, you’ll hear nothing but static.
