I did a little more testing using the irf520A and the IRF520N. I get a noticeable difference of almost an additional 8-10 watts average on a bird. One other difference was that the input was alot harder to get a low SWR. i got it down to a 1.5 on the input with the N type were as i had a 1.05 on the input with the A type. This was using my LP-100. Just thought someone would like to know this. I believe that the N type has a higher capacitance that is harder to cancel out.