The DL-2 is a QRP+ dummy load with a RF detector circuit that allows a standard Voltmeter to be used to measure RF power out, ideal for anyone adjusting homebrew QRP Transmitters. It also as an LED indicator to show when RF is present. Power as low as 50mW (or even lower) will cause the LED to light.
This type of device is not new, in fact the idea is many years old but unlike many designs the voltage tap off point is not directly taped across the 50 ohm load. In this design, the tap point is moved to a position that will protect your radio even if the voltage out terminals are short-circuited.
The DL-2 is built into a small case and makes a great bit of test equipment. It uses a bank of resistors to provide a good 50-Ohm match and each resistor is rated at 2 watts, this gives a working wattage of 16 watts max.
In practice it has been found that higher power levels can be tested if the transmission time is kept brief but do keep in mind the rating of the resistors.