Binary factory now only has an unstable build for Windows - the download link for Windows from the Konversation site points to the stable build job which no longer exists. (https://binary-factory.kde.org/job/konversation-stable-win32/)
It seems the binary factory link has changed to: https://binary-factory.kde.org/job/Konversation_Release_win64/ But this will open the Jenkins build page. To get the installer it will be something like: https://binary-factory.kde.org/job/Konversation_Release_win64/lastSuccessfulBuild/artifact/konversation-1.7-39-windows-msvc2017_64-cl.exe But the problem is that the above is bounded to the build number and it builds automatically from time to time. Probably it has a better link or place to provide it.
https://konversation.kde.org/download.html now links both stable & unstable windows builds, no longer any 404.