External AIS unit fault: Antenna VSWR fault

[Pat T]

I had this fault show up many times, usually all I would do is cancel it but it would eventually show up again. In research it says it could be attributed to antenna connections. I have recently replaced my antennas (Shakespere), VHF's(Icom) and MFD's (Raymarine Axiom). Antennas came with new cables.
Hoping the new equipment would rid me of problem but nooooo!
I do have Ramarine AIS 100 splitter and Raymarine AIS 650 class B transceiver.
Further research into troubleshooting indicates using a VSWR meter and/or updating software of the transceiver.
I see SWR and VSWR meters on Amazon. What is the difference? Can you recommend a meter to buy to troubleshoot this issue? Looking at where these AIS boxes are in my boat I wonder if extension cables are needed/advisable to use with a meter?
Any help is appreciated.

 

[Iggy]

Are you using a AIS antenna? Or a VHF one?

I had a VSWR problem, I was using a VHF antenna.

They do make a broad band VHF antenna that will work with AIS too.

 

[Pat T]

Are you using a AIS antenna? Or a VHF one?

I had a VSWR problem, I was using a VHF antenna.

They do make a broad band VHF antenna that will work with AIS too.

Iggy, Didn't know there was a difference. Am using a splitter so thought VHF and AIS would be able to use same antenna? Thanks.

 

[Comodave]

I would get rid of the splitter and use a dedicated AIS antenna. I bought a 4’ one for our last boat and it worked great. I don’t like splinters in one of the primary emergency devices, VHF radio.

 

[Iggy]

Iggy, Didn't know there was a difference. Am using a splitter so thought VHF and AIS would be able to use same antenna? Thanks.

I was not using a splitter.

https://defender.com/en_us/shakespeare-classic-ais-antenna-396-1-ais tuned to 158Mhz

https://defender.com/en_us/shakespeare-quickconnect-vhf-antenna Tuned to 156.8Mhz

Just to be clear, I am not endorsing these antennas but to show how they work.

What is happening is that some of the TX power is not being used by the antenna. A mismatch, or a VSWR error. This will also limit your AIS output range.

 

[Comodave]

This is the AIS antenna I used on our last boat.

Shakespeare 5396-AIS Galaxy 4ft. Little Giant by Shakespeare

 

[twistedtree]

The cables in question would be



1) Cable from AIS to splitter


2) Cable from Splitter to Antenna.


Are both cables new? Are they factory made? Are any of the connectors "solderless" connectors?


If it doesn't take too long for the error to trigger, then a good test would be to connect the antenna cable directly the AIS, bypassing the splitter. That might help narrow down where the problem is. The splitter is a possible culprit too.

 

[Pat T]

The cables in question would be



1) Cable from AIS to splitter


2) Cable from Splitter to Antenna.


Are both cables new? Are they factory made? Are any of the connectors "solderless" connectors?


If it doesn't take too long for the error to trigger, then a good test would be to connect the antenna cable directly the AIS, bypassing the splitter. That might help narrow down where the problem is. The splitter is a possible culprit too.

Thanks. Cable from splitter to AIS is not new but cable from splitter to antenna is new since I used the new cable that came with antenna. Not sure if any are solderless but assume the factory made Shakespeare is probably solderless.

I may be able to run the antenna directly to the AIS. I will investigate. Thanks again for suggestion.

 

[twistedtree]

Thanks. Cable from splitter to AIS is not new but cable from splitter to antenna is new since I used the new cable that came with antenna. Not sure if any are solderless but assume the factory made Shakespeare is probably solderless.

I may be able to run the antenna directly to the AIS. I will investigate. Thanks again for suggestion.

The solderless connectors are junk.

 

[Pat T]

Went out to the boat and first thing I did was to disconnect/reconnect the cable from the splitter to the AIS. Seems I tried that before. After that I could not duplicate the problem so hopefully I have narrowed the problem down to that cable. Luckily this cable is fairly short and easy to get at if I have to replace. I just need to brush up on my soldering skills and purchase the correct cable and connectors. From what I remember there were different connectors on each end.

 

[twistedtree]

Went out to the boat and first thing I did was to disconnect/reconnect the cable from the splitter to the AIS. Seems I tried that before. After that I could not duplicate the problem so hopefully I have narrowed the problem down to that cable. Luckily this cable is fairly short and easy to get at if I have to replace. I just need to brush up on my soldering skills and purchase the correct cable and connectors. From what I remember there were different connectors on each end.

That would be odd if the connectors are different on each end. Typical AIS and VHF connectors are PL259. You can get pre-made cables in nearly any length for reasonable cost, and I'd suggest just getting one and replacing the old cable. If it cost you $20 it would be a lot. And I'd replace the cable from the VHF to the splitter at the same time. Cheap insurance, and no need to worry about how good a job you did soldering the connector.

 

[Berwick]

I had this exact problem with my Axiom unit. Went to a dedicated AIS antenna (as suggested above)and bypassed the splitter and that solved the problem.

 

[Comodave]

The solderless connectors are junk.

Same with a lot of splitters.

 

[Helmsman]

AIS transmit at around 162 mhz. You mentioned the antenna you are using for AIS is 158 mhz. I have a Cortex and am using a 159 mhz which services both AIS and VHF. Maybe not worth replacing, but if it continues you may want to consider getting an antenna made for AIS.

 

[twistedtree]

Same with a lot of splitters.

It wouldn't surprise me. I think a splitter is something to use when you have no other alternative. Two antennas is clearly the preferred solution, if you can make it work.

 

[Pat T]

That would be odd if the connectors are different on each end. Typical AIS and VHF connectors are PL259. You can get pre-made cables in nearly any length for reasonable cost, and I'd suggest just getting one and replacing the old cable. If it cost you $20 it would be a lot. And I'd replace the cable from the VHF to the splitter at the same time. Cheap insurance, and no need to worry about how good a job you did soldering the connector.

I'll have to check those connectors again to be sure. Hopefully they are the same. Good to know pre-made cables available. Love this forum for this info!
Thank-you.

 

[Pat T]

I hear you all about the dedicated AIS antenna. When all else fails.
Thanks.

 

[L57]

Power Splitter

I had this exact problem with my Axiom unit. Went to a dedicated AIS antenna (as suggested above)and bypassed the splitter and that solved the problem.

The power splitter device will reduce the input side rf-power by half (antenna inputs). As you say, direct antenna to receiver/transmitter connection is the most reliable.

 

[Hippocampus]

I would get rid of the splitter and use a dedicated AIS antenna. I bought a 4’ one for our last boat and it worked great. I don’t like splinters in one of the primary emergency devices, VHF radio.

For several reasons don’t like splitters for AIS/VHF. Have found both work better with their own designed for that purpose. Also it gives you redundancy. On the last boat left the splitter in place where it was attached but removed it from both devices and the antenna If either antenna got damaged it then would take a minute or three to reattach to both devices and a good antenna.

Also need to think about whether you want 3dB or 6 or 9 for both or different gains for each one. From the little I understand that depends upon how you use the device. So if you only use the vhf to contact and talk with folks close enough to see 3 should serve. If you talk for stuff farther away you’ll want the most gain you can get. At present believe the boat came with 6 . Want was said above about frequency the antenna is tuned to best also matters. A lot depends upon what’s available for attachment points and height restrictions. Still a dedicated antenna for each device is a good idea ( be it multiple radios, AIS etc.) in my humble opinion.

 

[amxr39]

I would get rid of the splitter and use a dedicated AIS antenna. I bought a 4’ one for our last boat and it worked great. I don’t like splinters in one of the primary emergency devices, VHF radio.

There are a few companies that make broad band antennas that have a center frequency of 159 mghz with a bandwidth of 6 Meg and another company makes one with a 10 mghz bandwidth. Digital antennas and the other company name begins with M. Can’t remember it. I have a Vesper Cortex. They used to make a broadband antenna but Garmin discontinued it. Garmin support for antennas is nil. I do know all Shakespeare antennas have a 3mghz bandwidth and are not suitable for AIS.