[codefox1]

The main loop is wired in parallel with the variable capacitor. One section 10-365 is good enough for most of the AM band, but an additional section added will tune lower. You can use a toggle switch to add or subtract sections fixed capacitors to make use of what you have on hand. The sensing loop is used just to connect to the Antenna and Ground terminals of the radio and is not connected to the main loop. If the radio is in close proximity and has an internal ferrite or loop antenna no direct connection is required, so in that case the sensing loop is not used or needed.

You tune the radio, then the loop's capacitor, and back and forth to get the best reception on any given channel. Note this arrangement is highly directional, so you can indeed get two stations on one channel, sometimes both are readable.