Good question, but based on my experiences with the DSB sync detectors
in the Drake R8 and the Lowe HF-225, I would have to say that the
modified R-75 worked as well as the 225 and definitely maintained
better lock on signal fades than the R8. So, I would have to say that
it worked properly, at least on the one I modified. The best sync
detectors I've seen are in the Drake SW2 and the Lowe HF-150. They are
SSB selectable.

Frank