100 Watt 40m HF amplifier using air ( plastic ) core inductor
This amplifier is used with 40m QRP rig and IC-718. Power output drops with increasing frequency. This can be used on 30M for FT8. At 20M power output drops to 4 Watts :-(. At 80M power output was more than 150 Watts on dummy load however it was not used on 80M band. Objective of this project was to use IRFP450 MOSFET in the final stage of a linear amplifier for lower HF, using unregulated power supply. IRF730 MOSFET is used to drive the two IRFP450. Here is the circuit... Some resistors were paralleled to increase wattage. These are drawn with thicker lines. This picture explains how paralleled resistors are shown in the schematic. R1 ... R10 are paralleled resistors. Values of the resistors are shown on the diagram and are repeated here. R1 = 3 || 470R/2W = 156R6/6W R2 = 3 || 470R/2W = 156R6/6W R3 = 4 || 150R/2W = 37R5/8W R4 = 4 || 150R/2W = 37R5/8W R5 = 4 || 27R/2W = 6R7/8W R6 = 4 ||