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'
![Sad :(](https://www.eevblog.com/forum/Smileys/default/xsad.gif.pagespeed.ic.L3FGyzQrjB.png)
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).
![Smiley :)](https://www.eevblog.com/forum/Smileys/default/xsmiley.gif.pagespeed.ic.R8GFI-pF6f.png)
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