25 Oct 2010
A fairly easy way to increase my ERP on 137.5kHz WSPR is to up the supply voltage to the IRF510 PA. Using a 20-24V supply I was able to get another 3-4dB ERP judging by the reports from M0BMU and G3WCD this morning. This evening I'll give it a go with the higher supply to see if I can get any reports from further afield. I've also thickened up the bottom part of the loop which will reduce the resistive losses by about 15%.