Voltage blocks are used primarily with preamplifiers. Used when a signal splitter is installed between the outdoor preamplifier at the antenna and the indoor preamplifier power supply. They are installed on all output ports of the splitter except for one. The output line that leads to the power supply is connected directly to the splitter. Also the antenna input on the splitter does not require a voltage block. This allows the power from the indoor power supply to travel through the signal splitter directly to the preamplifier at the antenna and not to the remaining TV outlets.
Learn when and why to use a voltage block with your mast mounted preamplifier.