In plain language: “RF in the shack” means unintended common-mode RF voltage or current is present on equipment, cables, accessories, or nearby conductors instead of remaining in the intended antenna system.
Why the station behaves this way
It can cause microphone bites, audio distortion, computer faults, unstable tuners, touch-sensitive SWR, or interference. The cause is usually a complete-system current-path problem, not simply “too much power.”
A common wrong turn
Adding a station ground wire without understanding the current path can create another radiator or worsen the symptom.
What to do at the radio
Reproduce the fault at low power, inspect the feed and return path, test common-mode current, improve feed-point choking and bonding where documented, reroute cables, and retest one change at a time.
Operating boundary
Use current equipment instructions, legal operating limits, the exact signal path, and observed conditions. A connector, software label, transformer ratio, or forecast value does not prove complete-system performance.
