26 Nov 2009
Our little 2 year old grandson has come to stay for a few days, so I'm unlikely to get much operating time until Sunday evening. I have to rebuild my PA before I can get back onto 500kHz TX, so it may well be next week before I'm on the band again. I shall try to listen as and when I am able. The main information I've gathered on FET PAs (especially in class D/E) for 500kHz is to make sure the antenna is well matched (i.e. don't adjust the ATU/matching when the PA is on), don't exceed the peak voltage rating on spikes, ensure that parasitic oscillations are well suppressed and be generous with the heatsinking.