The Directional Power Meter R&S NAUS 4 is handy and easy to operate. The instrument consists of an indicator and a separate measuring head, which can be connected in either direction. The forward and the reflected power are indicated on separate meters. It is working in the frequency range between 25 and 1000 MHz. The power range is divided into five subranges and extends from 50 mW to 100 W, in the most sensitive range f.s.d. is obtained with 1,1 W. The indication is highly stable and insensitive to temperature fluctuations. Both meter scales are lineary calibrated and can be easily read. True average power indication is also given of non-sinusoidal signals (modulated transmitter). The power supply needs five 1,5 V batteries (R20).