AIS Antenna Troubleshooting - Poor VSWR possible causes?

[Wotname]

Originally Posted by abarrow

If there is a break in either the shield or the center conductor, all power will be reflected at that point, and will show nearly 100% VSWR.

Not always, it depends on the length and loss between the TX and the break.
Try it yourself - connect say 40' of RG58 to the TX and leave the far end of the coax open (unterminated). Measure the VSWR at the TX and you might be surprised at the result.

[Longo Mai]

I had the same problem with my antenna at the mast head. I cut the RG58 cable close to the antenna, used a solder connectors and replaced all the cable with RG213. I then had very good VSWR but I can’t recall a specific reading.
Compare the tech specs of the cables and RG58 suitable for short runs

[Bluechart]

Test for an Open Circuit (Continuity Test): Set the multimeter to the continuity or resistance setting. Touch the probes to each end of the wire you want to test. If the wire is continuous (no breaks), the multimeter will beep or show a low resistance reading. If there is no continuity, it indicates an open circuit.

Unplug the wire from the radio/AIS unit, hold one probe on the center pin, hold the other probe on the outside of the fitting, this should be open, no sound.

If sound, then you have a short between the center pin and the outside shielding, it could be just one strand of shielding touching the center pin, that will destroy radio and AIS transmission.

[s/v Jedi]

Of course it is the connector. It has been the connector and/or the attachment of the connector every time and ll the time.

I have never encountered an installation with antenna trouble where it wasn’t the connector or cable.

The only chance you have is either ask someone qualified to do it for you or buy expensive crimpers with expensive connectors made for that crimper, like from Times Microwave.

I highly recommend to find someone to do this for you.

For me, when inside with good access, I use original Amphenol solder connectors with my Weller digital soldering station. When outside this doesn’t work at all as there is too much cooling so I use solder for the center pin using a Portasol gas powered soldering pen, then crimp the outer braid. My crimper is 40 years old so no pointers for that..

I almost never have to solder outside. When I install a new cable to the masthead, I install the connector for the masthead side beforehand and feed the new cable from the masthead down. If that’s not possible, I solder the center pin beforehand and crimp the rest outside.