Here is an update of this morning's measurements, mostly consistent except for a couple of values
for which I must have forgotten to set the RF gain when launching the GNURadio application,
and the addition of the measurements at 1090 MHz

FM modulation: synthesizer output power in order to reach 10 dB SNR (3 kHz modulation,
5 kHz deviation). All values in dBm
E4k FC0013 R820T
137 MHz -105 -112 -112
434 MHz -105 -111 -112
1090 MHz -96 -76 -109
1500 MHz -95 -58 -102 <- major correction !

AM modulation: synthesizer output power in order to reach 10 dB SNR (3 kHz modulation,
30%). All values in dBm
E4k FC0013 R820T
137 MHz -109 -116 -117
434 MHz -110 -115 -119
1090 MHz -101 -80 -113
1500 MHz -101 -62 -110 <- major correction !

JM