My version of
the loop is based on the information in this QST article:
I added several modifications to N7FKI's design. A one-turn pickup winding fed to a BNC connector was included for use with receivers with a low-impedance antenna input. This facility has been little used as the loop is generally used with portable receivers with internal loop antennas by placing the RX on the built-in pad as pictured below. Fahnestock Clips were installed in parallel with the 365 pf tuning capacitor to allow a range of fixed padding capacitors to be inserted to lower the tuning range into the beacon band - see capacitor values in last photo. A switch was installed to insert a 47 pf mica capacitor in series with the 365 pf tuning capacitor to spread-out the tuning at the upper band-end and to assure tuning to 1700 KHz. If I were to do this again I would probably make this capacitor slightly smaller.
The sensitivity boost provided by this loop is quite considerable often bringing signals which are barely there up to a fully readable level. I have used it mostly with the Tecsun PL-380 or a Sony 7600-GR. The Tecsun is fairly deaf in the beacon band and the loop makes it usable there.