This circuit is for a QRP (low power) antenna tuner, a.k.a. a transmatch, for use in the short wave amateur radio bands from 3-30 Mhz. It allows a wide variety of antennas to be connected to a low power transmitter. When the circuit is properly tuned, the maximum transmitter power will be delivered to the antenna. It is used in conjunction with a standing wave ratio (SWR) meter. This is a fairly generic antenna tuner circuit.
Build the tuner in an aluminum project box. Drill holes in the box to mount the various components. Leave plenty of room around the sides of the components to prevent RF arcing. Be sure to keep both sides of the variable inductor insulated from the box, y