The individual PAs used here to achieve about 500W composite output are detailed below. Measurements are in mm unless otherwise indicated to be inches. Materials readily available in the west are used, making the purchase of components with which to construct these PAs somewhat easier to obtain than for some designs. This design has been successfully tested using both the GI-7B triode shown in the picture, and the somewhat more robust GI-7BT version of the tube. Dimensions not specified are in mm unless indicated to be in inches. Drill a 1.5mm hole in the center of each disk. Cut 2 x 12mm lengths of 1.5mm diameter rod. cool the rods in ice for 20 minutes. Heat the disks to 400 degrees F in an oven. Carefully place a disk flat on a ceramic surface capable of handling the heat. Take a cold, dry rod and place it in the hole in the center of the disk, being careful to insure it is perpendicular to the disk. Allow to cool; the rod will expand and the hole contract, making a sound mechanical bond. Solder the rod to the disk on the rear of the assembly. Use very fine sand paper ("crocus cloth") to insure the front of the assembly is flat and smooth.