E4403B ESA-L Spectrum Analyzer 9kHz - 3 GHz Opt 1DN 50 Ohm Tracking Generator.

I have used this ESA series analyzer very successfully for some years to develop ionospheric sounding hardware. Unusually it has the Option 1DN 50 Ohm 3 GHz tracking generator in addition to the usual Option A4H GPIB $ Parallel interfaces. It is fully functional below about 2.7 GHz. If set to scan above that frequency the analyzer shows "Source Unlock" and similar errors from the tracking generator that I have never been able to fix. See the attached screen shot. I will include the GPIB to TCP/IP network adapter that enables the use of HP PC software to acquire data as an alternative to the 3.5" floppy drive. I also include the ESA series manuals. "Reference Guide", "Users Guide" and "Calibration Guide". The BIOS software backup battery was recently replaced.