A Front End Limiter is a passive device that protects a receiver from an excessive signal preventing that excess RF can damage it. It is important to keep this concept in mind, since the mission of an FEL is to protect a receiver from strong and excessive signals. Obviously, it must be installed between the antenna and the receiver. For example, when we have a receiver or SDR and in the around area we also have a transmitter, depending on the distance between the TX and RX antenna of the receiver and the power used, we must protect the receiver.
We have two models of equipment that include this FEL functionality depending on the use:
- RX-FEL: Includes an FEL with input and output connectors (SO239, RCA or BNC). It is a model for only receivers and cannot be transmitted by it.
- TRX-FEL: Includes an FEL with input and output connectors (SO239) but it differs from the previous one in that by means of relays you can make a bypass of the FEL. For this it has a power input and PTT signal input. In this way, if the PTT is connected to the tranceptor, when it passes to TX, the TRX-FEL is in bypass mode and can be transmitted without damaging the FEL.