Figure 4-1: First Prototype - IRF510 Power Amplifier
As figure 4-1 above shows, the previous design had the FET laid down with the PCB mounted to the heat sink. It was good for a quick prototype, but is not necessarily the most efficient approach.
|Figure 4-2: Updated Power Amplifier Layout|
I looked into a different layout where the FET itself was on the heatsink, while the board it mounted on standoffs at right angles as shown in figure 4-2. At the same time that I sent in the updated DDS interface, I also sent in this Power Amplifier as well.
Once I get the amplifier design finished, I will be publishing the schematic for the power amplifier - hopefully in QST or QEX - along with the PICAXE interface design. At very least, VWS will get the design for one of their tech journals when it comes out. Figures 4-3 through 4-6 show the broadband sweep of the amplifier.