Our AIT2000 and AIT3000 Class B transponders are supplied with a GPS antenna that has a 10m cable terminated in an FME connector (right hand connector in the above image).
These connectors are very slim, not much larger than the coax cable and are much easier to route through the boat. We also supply an FME to TNC adaptor for connecting the cable to the transponder (left hand connector in the above image).
Today we were reminded of the importance of ensuring this adaptor is firmly screwed on to the cable, when a US customer reported that their AIT2000 had stopped getting a GPS fix. After using the proAIS2 software to confirm that the GPS signals were very low, we asked the customer to check the GPS antenna connections to the AIT2000 and sure enough found that the FME connector had become loose and was no longer making a good connection.
A quick tighten of the FME connector in to the adaptor and the AIT2000 started to get a GPS fix again and the customer could continue their cruise.
The nut on the FME connector is 8mm (AF) and the TNC adaptor has two flat indents that are 9.5mm (AF). You can tighten the two connectors quite tightly but avoid using too much force which could damage the connector and cause a different set of problems. The image below shows the FME fully tightened in to the adaptor and there should be about a 1.5mm gap between the FME nut and the collar of the adaptor when properly tightened.
Our GV30 combo GPS and VHF antenna also uses FME connectors and is supplied with a TNC and BNC adaptor, which should also be tightened in the same way.