AJ
Can you try attenuating the input to ensure you are not in compression?
There is a 20db fixed attenuator on the input of the SH and the Ref Offset is set to 20db.
With your ref offset active, set the reference level to +40 to see if this affects the measurement. I am concerned that the signal is possible being compressed in the Spike software.
I have changed the Ref Level from +40 to 20dbm with very little difference in peak power measured.
If you have a generator, can you try a similar test?
I don’t have a generator other than the radio being tested. It’s output is +20dbm.