Fast, Friendly Facts About Front End Preselector

If you’re a ham radio or shortwave radio enthusiast, or you were a radio operator in the army, perhaps you’d know how valuable “preselectors” are. A preselector is defined as an electronic device inserted or placed between the antenna and the receiver. This limits the range of frequencies that can be applied to it.

When you tune the receiver to the desired frequency, that keeps the device’s narrow bandwidth centered on the operating frequency. This also rejects or reduces the interference of out-of-band or unwanted signals. Here’s a look at the capabilities of a preselector front end.

What is a “Front End”?

Before we go ahead and discuss the technical specifications of such a device, though, let’s first discuss what “front end” means. In the radio frequency field, the term “front end” is actually a generic term that refers to all the circuitry between the antenna, up to and including the mixer stage.

The front end also consists of all the components or parts in the receiver that processes the signal at the original incoming radio frequency, before it is converted to a lower intermediate frequency.

In satellite and microwave receivers, the front end is usually referred to as the low-noise block or low-noise downconverter, and is situated at the antenna. This is so that the antenna’s signal can be transferred to the receiver in an intermediate frequency that can easily be managed or handled.

In smart phones, multimedia devices and even home entertainment control systems – which rely on the reception and transmission of wireless signals – consumers will also find an RF front end.

Why Preselectors Are Valuable Items

How would receivers ever survive without preselectors? A preselector helps protect a receiver’s sensitive output from damage that’s caused by static, voltage transience, as well as very strong signals from nearby transmitters.

A preselector also helps enhance the performance of any type of receiver, although it’s deemed more helpful for receivers with broadband front-ends like scanners or regular consumer-type receivers. The device also helps with the extra filtering of signals.

A receiver’s front end, which conforms to the same settings as the mixer and RF power amplifiers, usually has a limited dynamic range. In addition, these circuits often have a limit to the amount of RF energy they can handle without overloading.

If the receiver’s front end overloads, it can severely affect or even damage the overall performance of the device.

Like all preselector types, front end preselectors are often tuned to have a narrow bandwidth, typically centered on thhe receiver’s operating frequency. The preselector then passes the signal it is tuned to (albeit slightly reduced).

It then attenuates other signals, considerably reducing or diminishing noisy and unwanted interference, leading to a clearer transmission.

In addition, it’s possible to design or engineer a preselector front end that can protect a receiver from signal overloading and sudden voltage spikes. The major drawback however is these devices do not remove interference emanating from the same frequency the receiver is tuned to.