A masthead amplifier is usually fitted to an external aerial or is in the loft. They can also be located indoors behind the TV but this is unusual.
Masthead amplifiers offer much the same number of outputs and signal uplift options as distribution amplifiers but are constructed to handle outdoor conditions such as extreme cold and hot weather or rain. The amplifier itself is usually covered by some form or waterproof casing. They also tend to have threaded connections (F Connectors) that are more robust and provide better connections.
If the casing is fitted incorrectly or gets damaged over time, changing weather can impact the product and cause picture disturbance.
Masthead amplifiers typically have a separate power supply unit (PSU) which, if located in the roof, can suffer from severe cold or water ingress causing them to fail leading to loss or poor picture.
Amplifiers or splitters that are located on the roof, outside of the property or in the loft will normally have an F Connector. F plugs and sockets have threaded (screw style) connections as shown below:
There are two principal aerial connectors for TV systems.
Coaxial (coax) connector in both male (plug) and female (socket) forms. The coax connectors are sometimes referred to as a Belling Lee plug. Coax connections are usually seen on domestic devices intended for indoor environments. They are relatively easy to connect but if done incorrectly, allowing inner and outer cables to touch, or are loosely fitted, could cause TV picture disturbance.
F Connector, so called as the F stands for ferrule, as the connector was attached to the coaxial cable by crimping a band (or ferrule) to hold it tight. As with coax connectors, there are male (plug) and female (socket) counterparts.
The F connector is used for connecting terrestrial, cable and satellite TV systems as it provides a robust and reliable connection and is less prone to causing or suffering TV interference. It is typically the connection type seen on roof top amplifiers and increasingly on terrestrial TV aerials.
An attenuator is a small device that is designed to reduce unnecessarily high TV signals that could otherwise cause distortion leading to TV picture disturbance.
When the UK digital switchover took place between 2007-12, terrestrial TV transmission powers were increased. This meant many homes did not need to use amplifiers. However rather than remove their amplifier, many homes retained them and may now suffer periodic disturbance when 4G signals are added to the already high TV counterparts. In such instances, there may be need for an attenuator in your system. The fixed variety look similar to an existing aerial plug and have a fixed level of signal reduction capability.
The variable attenuator can be adjusted across a range of signal reduction (e.g. 0-20dB) and is usually a small dial or slider.
Attenuators come with coax or f type connectors.