Yes, you can measure any amplifier. (Converters
also)
Check the output power of the power
amp with a 50 ohm load on the input to be sure
you won't damage the NF meter. Measuring the
power amp with no input should work. The exception
to this would be class C amplifiers which won't
turn on without a strong enough signal at the
input.
If the gain is high or just to
protect the NF meter you can add an attenuator
after the amplifier. On the 8970, use 34.4 Special
Function, "Enter loss after DUT" to compensate
for the attenuator.
Joe thanks for the reply and sorry for
the delay. If I'm trying to calculate the kTB power
in dBm then do I need to place a filter on either
the input or the output of the PA to simulate the
operating BW? I'm only operating in a narrow bandwidth
compared to its total operating frequency range.