20 Nov 2009
My IRF510 500kHz PA has a tiny heatsink (soon to be addressed when a new heatsink arrives) and it is not very tolerant of poor antenna match. As a result it died again this evening in mid WSPR! This afternoon I managed to raise to PA output to 8W by changing values and this must have made the tiny heatsink just too small to be useable. I also need to find a better way of getting my antenna tuned to 50 ohms. This is all a good excuse to do a proper rebuild next week.