[RFI] Another Plea For Help

[Joe]

I posted this problem last month..I didn't really get much help so I will 
pose the question/problem again, in the hopes someone can suggest an avenue 
of discovery.  I am getting more and more frustrated.

Joe Wolfe
WA6RKN
Reno, Nevada
****************************************

About a month ago, my noise floor on 40 and 75m , ie:...white noise....rose 
to
9 and 10 over.  In the early AM, the noise floor is where it normally 
is...1 - 3 s
units.  Then, around 9 or 10, give or take, the noise floor gradually climbs
back up over 9.  Temperature does not appear to be the culprit.  Feed line
(RG-8X) tests good and no water present.  Balun was replaced..no change in
noise characteristic.  (Antenna is a BuxComm 6-80 Windom at 30 feet.)

I connected the radio (Kenwood T-2000X) to a battery, and turned off the
master switch so no power was coming into my house..  No change in noise
level.  There are no overhead wires in my neighborhood and the closest major
overhead power line is a mile and a half away.

The frustrating thing is that it is pure white noise..no electrical type of
noise...buzzing, chirping, whistling, crackling, etc., just what you hear
for a noise floor.

Any thoughts?  What instrument would be needed to have something like this
down?  The AM radio trick sure doesn't work...no overhead transformers to
knock about.  Mercury vapor street lights are off when the noise level
starts to climb in the late morning.