Ferrite Suppressor / RF Filter

The RDL ST-FS6 is a passive ferrite suppressor and RF filter for reducing radio-frequency interference in audio or control circuits. It provides suppression for six audio conductors without adding capacitance to ground or series resistance. The specified attenuation is greater than 10 dB at 10 MHz and greater than 25 dB at 200 MHz. Because the module requires no power, it can be incorporated without a separate power supply.

Ideal Use Cases

The ST-FS6 is intended for audio and control wiring that requires RF suppression. It accommodates both shielded and unshielded audio cables, making it applicable to several conductor and shield arrangements. Inputs 1 and 2 may be used to suppress a single pair while that pair’s shield is connected to ground. When suppression of the shield is also desired, Input 3 may be used for the shield. Its six-conductor capacity also supports installations involving more than one audio conductor pair.

Why Choose This Model

This model combines passive operation with a suppression method that introduces neither capacitance to ground nor series resistance. Those characteristics are explicitly defined for applications where either added circuit element is undesirable. The ST-FS6 also provides two published attenuation reference points rather than describing RF suppression without measurements: attenuation exceeds 10 dB at 10 MHz and 25 dB at 200 MHz. Six suppressed audio conductors provide a clearly defined capacity for planning circuit connections.

Installation and Integration

The ST-FS6 may be connected to shielded or unshielded audio cables. With shielded cables, the supplied application information indicates that the best RF suppression is often obtained by suppressing the signal conductors while connecting the shield to earth or rack ground. Two ground screw terminals are provided as shield-to-ground connection points. These terminals are not internally connected within the module, so each serves as a separate tie point rather than an internal connection between shields.

For a shielded pair, Inputs 1 and 2 can suppress the pair while its shield is grounded. If the installation instead calls for ferrite suppression of that shield, Input 3 can be assigned to it. The stated ambient operating environment is 20° C to 60° C. Front and end panel diagrams are available in American and Metric DXF formats, and a PDF specification sheet is identified in the source data for installation reference.

Performance Highlights

The filter’s documented performance includes attenuation greater than 10 dB at 10 MHz and greater than 25 dB at 200 MHz. These values provide two specific RF-frequency reference points for evaluating suitability. Suppression is available across six audio conductors, and operation is entirely passive. No power requirement, voltage input, or powered control stage is specified. The absence of capacitance to ground and series resistance defines how the module provides suppression within the connected circuit.

What Makes It Different

The ST-FS6 brings together six-conductor ferrite suppression, passive operation, and flexible shield handling. Installers can ground a cable shield through the provided screw-terminal tie points or use an additional input when ferrite suppression of the shield is desired. The two ground terminals are deliberately not connected internally, an important distinction when planning shield connections. Compatibility with shielded and unshielded audio cables further separates the module’s conductor-suppression function from any single cable configuration.

Final Assessment

The RDL ST-FS6 is a focused choice for RF suppression in audio or control circuits when six-conductor capacity and passive operation match the installation. Its principal selection criteria are straightforward: no capacitance to ground, no series resistance, greater than 10 dB attenuation at 10 MHz, and greater than 25 dB attenuation at 200 MHz. Two ground screw terminals support shield grounding arrangements, while the input configuration also permits suppression of a shield when required. The available PDF specification sheet and DXF panel diagrams provide additional documented integration resources.