The Agilent 8563A has an internal pre-selector which means faster measurement and that can be especially important in automated testing. The 8563A has sensitivity of -120dBm and digital resolution bandwidths of 10, 30, and 100 Hz.
Frequency range: 9 kHz to 22 GHz
HP-IB
Synthesized tuning gives drift-free measurements
Measurement sensitivity: -120 dBm
Built-in frequency counter
AM and FM demodulators with speaker and volume control