LAN PRO-FIL 100Mbit protection

LAN is now an integral part of every QTH. It is used not only to connect the home LAN, PC, TRX, etc., but also to connect outdoor equipment - wireless internet, IP relays, rotators, etc. It is these outdoor installations that pose an increased risk of pulling surges into the indoor network. Another common problem is unwanted RF emissions from the LAN cable due to cheap LAN elements (WiFi), or TX signal intrusion into the LAN and interference with communications. Many of these problems can be avoided with our LAN PRO-FIL board.

Functional description

It is a 100 Mbit RFI filter consisting of two LAN transformers. These act as galvanic isolation and also provide common mode rejection (CMCC). CMCC improves the symmetry of the data pairs and thus the characteristics of the line - due to the swarm, the RF signal radiation from the cable is reduced and also the induction of the surrounding RF signal into the cable (nearby antennas). A high voltage protector is inserted between the transformers to divert surges from the lines.

In addition, the RJ45 connector labelled OUTSIDE contains surge discharge tubes (GDT) to discharge high voltage directly at the connector. These GDTs are connected from all conductors to a common ground screw (GROUND ME! Screw).

This protection board also contains Power-over-Ethernet (PoE) circuitry - that is, power to the unit via the LAN cable. This is the standard for passive PoE on wires 4, 5, 7 and 8. The PoE circuitry includes multiple surge protectors, reverse polarity protection and short-circuit protection. There are also several LC filters against RFI. Protection includes two differential filters and one common mode filter. PoE can be pass-through - between RJ45 connectors, it can act as a PoE injector, but also as a PoE splitter (jumper settings). So you can use these two boards to send DC power over a 100Mbit LAN cable and take advantage of all the protection.

You can use this board on only one side - for example, as a PoE injector and LAN protection for powering Wireless AP/client devices on the mast - but you will only protect one side. Another option is to use two boards between the end devices on the LAN.

⚠ CAUTION, IMPORTANT!: This board is unlikely to protect your equipment from being destroyed by a direct lightning strike. Minimising the effects of lightning is a more complex problem and requires a more comprehensive approach.

This board is designed to provide surge suppression and additional protection for indoor equipment. If more energy is discharged, this board may be damaged - shorting out the protection element.