This testing is with Grounding boxes in mind, just to see what the background RF levels and emissions are from stereo kit.

Radio Frequencies cover a very wide frequency range, the test equipment I have goes right up to 1GHz.
That is 1000 MHz or to put another way 50000 times the audio bandwidth.

RF energy is very pervasive, it is all around us and is induced into anything metallic. Even a screened lead will pick up RF on its outer braid.

The test kit is known as a spectrum analyser and shows the frequency along its X axis with the logarithmic amplitude on the Y axis.
The X axis is linear so shows frequencies from Zero to 1GHz, so each graticule line is 100MHz.

The Y axis shows signals above the noise floor mush at the bottom of the screen, at about 20uV. This is ten times lower than a low output moving coil cartridge to give a context.

Test 1.
A 1 metre whip antenna connected to show the background RF level.



Test 2.
A probable ground box lead connected, made from some RG58 coaxial cable.




A test lead was made to connect to only the outer shell of an RCA socket and used for subsequent tests.
Test 3.
Test lead connected a CD transport output. Transport mains OFF.



Test 4.
As test 3 but CD transport mains ON.



See the slightly raised mush up to about 430MHz.

Test 5.
Test lead connected to a SPDIF input of Bel Canto DAC3, mains OFF.



Test 6.
As test 5 but DAC3 mains ON.



Look at all those clock harmonics

Test 7.
Test lead connected to XLR output of DAC3, mains ON.




Test 8.
Test lead connected to spare input of KIN preamp, mains ON.