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Upgrading to Co-Pol and X-Pol | Upgrading a 4006-7 to X-Pol/Co-pol | Balancing after Co-pol Upgrade | Marine Satellite Systems specializes in copol and BUC upgrades. |
Most VSATs in Europe and the Americas transmit on one pol (horizontal or vertical)  while receiving on the other pol. The feed on the back of the dish has the transmit and receive ports physically at 90 degrees to each other. This is known as Crosspol or X-pol.

In Asia, however, many satellites require the terminal to transmit and receive on the same pol, or Co-pol. So vessels going to the Pacific and Indian oceans either need to have a model -33 antenna, or have a Co-pol upgrade fitted to their antenna.

A second LNB is fitted by a diplexer to the transmit waveguide. The diplexer keeps the transmit and receive signals apart while allowing the second LNB to receive the signals on the same pol as the transmit.

Assemble the diplexer and waveguide pieces as shown in the photograph above, taking care to install the supplied half O-rings where required.

Remove the existing waveguide piece and substitute the diplexer assembly. Install the co-pol LNB and run the coax across to the FSK modem on the other side of the antenna. Some antennas have a coax switch to toggle between the co-pol LNB on the diplexer and crosspole LNB on the feed. This can be switched from the antenna controller below.  A simpler method requires a trip to the antenna when the vessel needs co-pol operation to disconnect the one coax and reconnect the other.  This should not be any hardship, unless the vessel needs to switch back and forth often.

Here is a photo showing two 4006-RZA-7 antennas before and after the upgrade. The co-pol LNB has not yet been fitted to the diplexer.



The picture above shows the co-pol coax ready to be connected to the FSK modem when the vessel arrives in the co-pol footprint.

Again, this will require a major rebalance, moving and adding weights to the antenna.

Generally the weight needs to move forward, toward the dish and up toward the top of the equipment frame panels..

Over the years, we have had quite a bit of experience with antenna changes like copol and BUC upgrades and rebalancing antennas. It can be quite a complex procedure often taking more than one day onboard, and a little research beforehand to ensure that the proper waveguide pieces and mounting brackets are on site.

SeaTel sells upgrade kits containing all the parts one would need, and then some. It is often more cost effective to do a custom upgrade where we supply only the required components to accomplish the upgrade to the required level.