scswift:
What exactly do I do with this ground strap once I have it? Do I run the cable through it, or attach it to something? And how is that braided material better than say, a copper wire to ground?It does a much better job of dissapating 'rf' to ground. You would put it between the DC ground (chassis) and frame ground of your vehicle or water pipe ground in a house. The braided wire is much more flexible as well. 8 MHZ is 'RF', just above the 40 meter band.
As the other gentleman suggested, a transformer will help. An inductor (sometimes called a 'choke') between the amp and supply may also help. Use the formula 6.28 * Frequency * L (inductance in Henrys) to calculate XL (Inductive Reactance) in ohms. Of course the higher the XL, acts just like resistor in your circuit. As frequency drops, so to does the XL.