Just set up my first HF station (IC-7300, G5RV at 30 feet) and having some odd issues. RF getting into my computer audio when running FT8 - the waterfall gets interference patterns every time I transmit, even at 50W.

My shack is on the second floor and I'm using RG-213 feedline with an MFJ lightning arrestor at the entry panel. Station ground is 8-foot copper rod outside the shack window, bonded to the electrical service ground with #6 AWG.

• Should I be running separate RF ground radials from the shack?
• Could this be a common mode current issue on the coax shield?
• Worth investing in a proper RF choke at the radio?

Classic common mode problem. Get a Mix 31 ferrite choke right at the radio - 10-15 turns of RG-213 through a big toroid. Also check your USB cable shielding to the computer. Sounds like your station grounding is adequate.

I had similar issues with my 7300 setup. Adding ferrite snap-ons to all cables in the shack helped, but the real fix was a 1:1 current balun at the antenna feedpoint. The G5RV can be notorious for common mode radiation.

Second floor installations can be tricky. Consider running additional grounding conductors - even #14 wire to water pipes helps establish a local RF ground plane. The lightning protection ground alone isn't always sufficient for RF.