An RF transmission line device with high performance, wide band characteristics includes an inner conductor for transmitting communication signals of a desired frequency band and a grounded outer conductor electrically insulated from the inner conductor by at least one dielectric material. A tap conductor is connected to the inner conductor and serves as an auxiliary path through which signals outside the desired frequency band can be externally injected into and/or retrieved from the through RF path, the tap conductor extending longitudinally through a tap housing conductively coupled to the outer conductor. As a feature of the invention, a modular attachment is removably coupled to the tap housing and includes a plurality of voltage suppression components that are arranged in the conductive path between the tap conductor and the tap housing, the voltage suppression components discharging transient voltages diverted from the inner conductor by the tap conductor.