Look, here's a simple example.
I have an HP8566B analyser here and it's noise figure is typically 24dB. i.e. the noise floor is -150dBm/Hz.
If I place a 27MHz amplifier ahead of it with about 16dB gain and a 5dB noise figure and try to measure the noise figure of the amplfier the analyser will get it wrong. This is similar to your proposed test at the first RF amplifier at TP13.
This is because the noise produced by the amplifier (gain plus noise figure) will be 3dB below the noise level of the analyser. i.e. the amplifier will churn out noise at
-174 +15+6 = -153dBm/Hz.
Therefore the analyser will make the amplifier look noisier than it really is because the internal noise of the analyser will mask the (lower) noise of the amplifier.
It doesn't matter if I use 10Hz RBW, 100Hz RBW or 1kHz RBW this noise will always be 3dB below the noise floor of the analyser and it will get the result equally wrong in every case assuming the RBW filters are ideally calibrated and corrected for making noise measurements.
Analyser noise floor..................Amplifier Noise output
-110dBm/10kHz ...................-113dBm/10kHz
-120dBm/1000Hz..................-123dBm/1000Hz
-130dBm/100Hz....................-133dBm/100Hz
-140dBm/10Hz......................-143dBm/10Hz
-150dBm/1Hz........................-153dBm/1Hz
Can you not see that the -3dB problem is still there even with the 10Hz RBW?
i.e. changing to a narrower RBW achieves NOTHING when trying to measure the noise output from the amplifier. It will still get the result wrong and will make the amplifier look noisier than it really is.
