I have E4402B, latest firmware version A.14.06. I also wanted to activate option 1DR - narrow RBW (below 1kHz). I have got license key and it was successfully activated, however I was not able to go below 1kHz resolution.
I have tried solution mentioned on Keysight forum as I have exactly the same setup, means software activated 1DR option but without 1D5 hardware option (high stability frequency reference) being physically installed.
https://docs.keysight.com/kkbopen/i-ve-upgraded-my-esa-with-option-1dr-narrow-resolution-bandwidths-yet-the-instrument-will-not-go-below-a-1-khz-bandwidth-why-is-this-589744737.htmlHowever this command sent over GPIB didn't work for me, regardless I tried several attempts including slight modification of that command :MMEM:DEL 'C:SYSTEM\DEFCONF'
Finally I decided to try brute force approach. I have erased flash memory, disconnected internal backup battery for a while, and then installed whole firmware package from the scratch. To my surprise, all hardware related options (e.g. 1DR, 1D6, etc) was kept activated and I didn't need to active those again. However all options based on personality software (e.g. option 226) were gone and I had to activate those licenses again plus installed appropriate personality software packages.
After this process (took 3 hours including physical disassembly to reach internal battery), 1DR option is finally working properly and I can set RBW down to 10Hz (minimum available without 1D5 option installed).
BTW, here is
excellent description of all available options, installation instructions, dependencies on specific hardware or if adjustment is required after installation. For example option 1DS (internal preamp), even I could activate it on my ESA I decided not to do so because after activation adjustment is needed to achieve expected accuracy, but I don't have software needed for adjustment.
https://docs.keysight.com/kkbopen/how-do-i-upgrade-my-esa-e-series-spectrum-analyzer-589310374.html