Question 32C5

Nearby HF transmitters can induce unwanted RF currents on the cables (coaxial, power, data) connected to sensitive equipment like an Inmarsat terminal. These induced currents, often common-mode, can enter the equipment's circuitry and cause interference or system failure. **Installing ferrite clamps on the coax cable (D)** is an effective solution. Ferrite material increases the impedance to common-mode currents flowing along the outside of a cable, essentially choking off the induced RF energy before it can reach the sensitive Inmarsat electronics. This directly suppresses the "induced RF." **Installing a longer ground lead (A)** is generally counterproductive for RF. Longer ground leads increase inductance, making them less effective for RF grounding and potentially creating resonant points that worsen interference. **Installing a low-pass filter (LPF) between the coax cable and antenna (B)** would block frequencies *above* a certain cutoff. Inmarsat operates in the L-band (1.5-1.6 GHz), while HF is much lower (3-30 MHz). An LPF on the Inmarsat terminal would pass its desired signals but block higher frequencies, which is not the source of HF interference. The problem is HF energy coupling into the system, not unwanted higher frequencies.