The Model 2520 is a fixed frequency (30 MHz) source at 50 ohms that provides an accurate level from -70 dBm to +20 dBm in 0.1 dB steps. It's level is NBS traceable using thermal converter techniques at 0 dBm and with NBS certified fixed attenuators at other levels. The 2520 is generally used for calibrating RF power meters, however, it can also be used to calibrate attenuators or video detectors,

etc.