[TG] [TG11] AIS 500 fault message while transmitting on VHF

[Tom - Raymarine - Moderator]

Hello Berwick,

Do the AIS and VHF share an antenna via AIS500's internal splitter, or do they have separate antennas?
Is the antenna the same as the AIS has always been connected to, or has something changed there?
Was there a VHF connected to the AIS before the new ICOM?

A Tx Malfunction warning when transmitting on VHF suggests to me either that the AIS tried to transmit at the same time and was blocked because the VHF was controlling the internal splitter - if you're using it, with a single antenna - or a supply dip caused by the current being drawn by the VHF. Does the Tx Malfunction appear every time you transmit or only occasionally, and does it make a difference whether you transmit on low or high power from the VHF?

Re. the VSWR warning: did you check the VSWR at the AIS frequency range, ~162MHz? Antennas that are good at around Ch16 on ~156MHz can be very bad at 162MHz.

If in doubt, the ProAIS PC software can give more diagnostic info, give that a go.

Tom