[CA11] AIS 700 VSWR Fault

[JPA]

I have been helping a friend with a partial upgrade to the electronics on a new to him 2006 Albemarle 280.

We have installed an Axiom Pro 9 with a pair of through hull RV transducers. Although we removed 1 of 2 E80 Classics to make room for a new Axiom Pro, we understand that the Axiom Pro and the E80 can not coexist on the existing STHS network so the Axiom Pro has been installed as a stand alone unit. The existing system did not include a STNG/NMEA 2000 network so at least for the time being, all data between the old and new systems will be separate.

We installed a very small STNG network. It is terminated at both ends, powered and its only spurs are the new Axiom Pro and AIS 700. This new STNG network appears to be working correctly.

We connected the new AIS 700 as follows:
- 12 vdc to a properly fused circuit
- STNG to the new STNG backbone
- Existing VHF antenna to "Antenna"
- Icom IC-M602 VHF to "VHF" via provided patch cable.

The vessel does not currently have an RF Ground point at the electronics but for testing purposes, I made temporary above deck connections between the new units and the engine and through hull bonding system.

When the AIS 700 was initially started the Axiom Pro quickly displayed an AIS target and dangerous target alarm for a vessel on the same dock but it also displayed an AIS VSWR fault alarm.

Unfortunately we did not have immediate access to ProAIS diagnostics. Suspecting that there were issues with the existing VHF antenna installation we charged right in and replaced it with a new West Marine/Shakespeare Mariner 8700. We understand that this 8', 5/8 wave, 6 db gain antenna is not ideal for AIS but thought that it would be workable for our purposes.

Unfortunately, installing the new antenna did not clear the VSWR fault.

After rounding up the ProAIS software, we found that voltage and GPS function was ok and the unit was sending and receiving but VSWR was registering at about 7:1.

The soldering job for the coax shielding at the new antenna connector was suspect. Not having another connector handy, we foolishly attempted to remove and re solder the existing connector which resulted in the worst possible VSWR at 99:1.

We replaced the bad connector and believe that it is installed correctly but VSWR continued to register at 99:1.

At this point we figured it was time for some technical support but on a whim, I moved the antenna connector from the "Antenna" connection point to the "VHF" connection point. With the antenna connected this way the AIS 700 appeared to work correctly. The VSWR alarm was cleared and the VSWR registered as 1.6:1 which is probably pretty close to the nominal spec. for the antenna.

We can't be sure if the original antenna was in fact defective, if the AIS 700's internal VHF splitter may have been defective from the start or if any of our installation or troubleshooting may have complicated the situation. Any advice as to how we should proceed would be greatly appreciated.

[Chuck - Raymarine - Moderator]

JPA,

We have received no similar reports and the AIS700 at my station is working as designed. It is recommended that the AIS700 be sent to Raymarine’s Product Repair Center to be bench checked / serviced.