If you've studied the drain waveform when operating inrto a correct load, and assuming its all within design guidelines, then the trouble is because of nasty impedances presented by the antenna durin
Hi Roger the FET should be rated to have a minimum operating voltage of at least 4 times the supply volts......... I guess you are using 12v?? This is quite inefficient with switching fets and the de
I've been using a single IRF510 FET PA stage on 500kHz and it produces around 6-7W of RF. But, when adjusting my antenna I've managed to damage several devices now. I think the stage is running some
Correction:- The IRF540 is also 100V rated, but a lot lower Rds on 0.05 ohms rather than 0.5 ohms for the IRF510. That may well contribute to overheating and damage on mismatch.
Andy, Thanks for the quick feedback. The 500kHz antenna is a 5m long vertical with a spiral top hat. It is fed via a (thickish) ferrite rod wound with the required inductance to resonate and this is
Hi Andy it is our experience that a properly tuned single ended Class-E PA is fairly docile and its power drops if presented with a mis-matched load. What you MUST NOT DO is tune the PA to the aerial
