HP 8904A / Agilent 8904A Multifunction Synthesizer (DC-600kHz) OPT 1/3/4

<p>
Opt 001 adds three more identical internal synthesizers which allows channels B, C &amp; D to be used as modulation sources for channel A.
OPT 003 adds fast hop and digital modulation capabiltiy (in frequency, phase and/or amplitude)
OPT 004 connectors on rear only.</p>