An addition to the above post.
The main reason I sent in that post was simply to demonstrate that by using bits and pieces of electronics hardware that most of us have kicking about - especially old stuff that we've forgotten about - can be used to make something useful.
This item could be made by almost anyone here. Apart from the obvious requirements for any project build, care is needed in its physical assembly on account of the high frequencies involved. And I'm sure someone could produce a better attenuator than my effort.
The cct. diag. is available on request: there is no patent on this design!
Al.