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uplink power for AO40



Simon GM4PLM wrote:

Charlie G3WDG was operational the first weekend using only a couple of watts and he could get a return on the downlink using milliwatts!

Wayne replies:

There is a huge difference between the downlink signal strength required to merely hear a carrier and the downlink signal strength required for Q5 copy of a SSB signal.  I can hear a carrier when it's several dB BELOW the noise level.  Q5 copy of SSB requires the signal to be several dB ABOVE the noise level.

Also, I wonder how much difference compression makes when people compare the uplink power of SSB signals.  Surely the intelligibility of weak SSB signals is more correlated to AVERAGE power than PEAK power.  The FT-847 has no speech processor in full-duplex mode, so the peak power may need to be a bit higher to get the same average power as another station that is using compression.  That is, 200W EiRP without compression may give about the same readability as 100W EiRP with compression.  Both signals probably have about the same average power.

Has anybody gotten a Q5 SSB signal report at apogee with 25W EiRP and no compression?

Wayne Estes W9AE
Mundelein, IL, USA

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