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Interesting discussion. Just a few very quick thoughts I think that you have to consider the average of the input power to consider the input impedance of the power device as the instantaneous power varies widely under SSB conditions according to the voice characteristics, as indicated by Farhan in the examples he?gives of varying input power. Otherwise, one can say that the low pass filter will not work correctly Furthermore, I think that it is not the case that the SWR varies according to the power, but that since you have more power output, the reflected power will be greater?with a greater indication?on the SWR meter. If the LPF is designed for 50 ohms at its output end the?SWR is not going to change with power as can be seen if the TX is terminated into a suitable dummy load, but will only change with the reactance of the antenna / feeder which does not change with power. The pi network in the old valve tx's is not a good example?because it was a matching network to tune the tx and match it to the antenna.?? What you were doing was matching the tx to the antenna impedance, whatever that was, which did not change according to the power, but what was changing was the pi network impedance transformation between the antenna and the PA according to the PA input power. Just a few quick thoughts for your consideration Regards? Lawrence On Wed, Aug 3, 2022 at 5:59 PM Ashhar Farhan <farhanbox@...> wrote:
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