As the G5 is a little portable, it is quite possible that it won't like a low impedance input (coax) all that well - it's simply not designed for it. Receivers like the R75 and the Alinco are, and that's one reason why Ridgescan has had success with his setup.
I would also avoid making the wire antenna too long - at some point, it's just going to be too much RF for a little portable and overloading will be the result. But what the hey, you won't hurt anything by trying it.
I would start by reorienting the antenna - get it as far from those power lines as you can, and if you can, run it at right angles to them. Grounding may also help - and there has been extensive discussions on what makes a good RF ground on this board and other places. Bottom line is, that a single 8 foot rod driven into the ground might not cut it unless you have a high water table (swampy) . In addition, if you can, get the antenna as far away from the home as possible. Only then would I consider a 9:1 transformer like the one WinRadio sells (via Grove).
I would also investigate whether the noise is only coming from the antenna. Wall warts are notorious for being causes of noise - sometimes you need to choke that off, or even replace it. Most of these are in cheap plastic with next to nothing shielding around them. A simple test would be to run the G5 on batteries, then on the wall wart. If the noise level goes up, remediation is in order.
HTH...Mike
