While testing RFI/noise issues I found this "Disturbance Simulator" to
be a very useful device.

http://www.edn.com/contents/images/101499di.pdf

Page 152

It is great for testing how effective RFI filetersI dispensed with C1,
R1, L1, C1 and C2, R2, L2.
I wanted the RFI to get back into the power line or "filter" I was
testing.

Filter in this case included distributed capacitors throughout the
house to see how effective
0.01 X Class would be. They are very effective.

The "Zener diode and MMICs...broadband noise" on page 158 of the same
PDF is a very
inexpensive and useful wide band white noise generator.

The current demands are low enough that a set of 3 9V batteries in
series will provide hours
of operation.

Terry