I guess I have bored everyone to tears by this point, but I finally
got an answer to a question that has bothered me for years:"Why did
the FCC chose the levels
specified in "Class A" and "Class B" digital devices?".

After several fruitless attempts at getting a straight answer from the
FCC, I lucked out. I met an retired engineer and he cited a "CBEMA
Study 2" that specified the lowest useful field was 48dBuV/M.

48dBuV/M is pretty damn weak. I now understand why devices that
clearly met "Class B" requirements, I know because I did the tests,
was still a horrible RFI
source.

Given the near uselessness of Class B, and the clear uselessness of
Class A,
ratings, the only option weak signal DXers have is to apply as much
filtering as we can afford.

If I manage to find a online version of what "CBEMA study 2" I will
post the link.

I did find one reference in an article written by Michel Mardigiuan.
http://www.ieee.org/organizations/pu...emcs/summer99/
comment.htm

Most of the references that I can find that mention "CBEMA" have more
to do with power mains quality then RFI/EMI issues.

Terry