If Launchpad rejects an upload to your PPA with the message

Rejected: Source/binary (i.e. mixed) uploads are not allowed.

it’s because Launchpad only wants the source package and you have also build a binary package. Just add the -S parameter to your build command to have a source-only build.

dpkg-buildpackage -S

or

debuild -S

After uploading the files Launchpad will use its build farm to build the binary packages. This usually takes about two hours but can also take much longer for some architectures.