The design shown is a simple unit for QRP operation on all authorized frequencies up to 30 MHz. based on a toroidal transformer Tl. The secondary winding of Tl samples a small amount o1 rf power. both forward and reflected, which is divided by the bridge circuit and rectified by diodes Dl and D2. Forward and reflected readings are obtained simultaneously on the two meters Ml and M2, and the bridge is matched and balanced at the required load impedance by Cl and C2.
See Fig. 56-9b for an alternative, less expensive, single meter version. The bridge also measure forward power.