I recently picked up two devices (not really toys) for testing and viewing what my antenna(s) see. Both were less than $60 and I think are a must on a sailboat.
NanoVNA
The NanoVNA is a small, compact Vector Network Analyzer. This tool has many functions, but the one(s) most notable for the sailor is the SWR and TDR functions. It will also tell you the impedance, the attenuation, and the velocity factor of the cable.
The SWR function will tell you if your VHF antenna is tuned correctly. Tuned meaning that Standing Wave Curve(SWR) is lowest at the Marine VHF Frequency Range. Low SWR is an indication that one is getting the most power available at the antenna to be radiated. The TDR function will tell you the length of your cable and if there are any problems with the cable, where along the length of he cable the problem lies. Two major problems are shorts and opens. TDR will tell you which.
The best part of the NanoVNA vs an SWR meter is the lack of RF power needed for testing. With an SWR meter, one must key the radio on a specific frequency to determine the SWR. With the NanoVNA, it generates an unmodulated sweeping signal across a specific range of frequencies which will not interfere with any communications in progress. The power output is about 3dBm (.002 watts). The end result will be a curve telling you where the antenna is currently tuned. One will still need to climb the mast to make adjustments unless one's mast has been unstepped.
TinySA
The TinySA is a miniature Spectrum Analyzer. Miniature in size, not in function. This tool will tell you what your antenna is hearing. This tool is not as important as the NanoVNA, but it you are having receive issues, this tool will tell you. How one uses it depends on what one wants to accomplish. If one has a handheld radio available, just attach the TinySA to the boat's VHF antenna cable and key the handheld radio. One should see a spike showing the power level and the frequency. If the spike is not present (assuming all settings are correct) then it can be assumed that the antenna is not working. This can also be used with the AIS antenna. One should note that this type of testing is intrusive, meaning, it will interfere with any communications in progress. Listening before keying.
TinySA also has a RF generator that is adjustable. One can connect it to the VHF antenna and test for output power without the fear of damaging your VHF radio. Again, using the handheld will help in determining if your are actually transmitting a signal or not.
Both tools are inexpensive and easy to use out of the box. There are multiple videos showing the uses of both tools. Too numerous to mention here, just do a Youtube search. Watch the videos and see if you might be able to use one, or both, of these tools.
Obviously one needs to be careful when ordering. Our friends in China are very busy cloning these tools and the clones do not work correctly. For the TinySA, go to the TinySA.org site and look for the recommended sellers. Some of the sellers also sell the NanoVNA.
Hope you find this info useful. Again, having useful tools on a boat when it comes to your communications equipment means keeping that equipment in proper working order.
NanoVNA
The NanoVNA is a small, compact Vector Network Analyzer. This tool has many functions, but the one(s) most notable for the sailor is the SWR and TDR functions. It will also tell you the impedance, the attenuation, and the velocity factor of the cable.
The SWR function will tell you if your VHF antenna is tuned correctly. Tuned meaning that Standing Wave Curve(SWR) is lowest at the Marine VHF Frequency Range. Low SWR is an indication that one is getting the most power available at the antenna to be radiated. The TDR function will tell you the length of your cable and if there are any problems with the cable, where along the length of he cable the problem lies. Two major problems are shorts and opens. TDR will tell you which.
The best part of the NanoVNA vs an SWR meter is the lack of RF power needed for testing. With an SWR meter, one must key the radio on a specific frequency to determine the SWR. With the NanoVNA, it generates an unmodulated sweeping signal across a specific range of frequencies which will not interfere with any communications in progress. The power output is about 3dBm (.002 watts). The end result will be a curve telling you where the antenna is currently tuned. One will still need to climb the mast to make adjustments unless one's mast has been unstepped.
TinySA
The TinySA is a miniature Spectrum Analyzer. Miniature in size, not in function. This tool will tell you what your antenna is hearing. This tool is not as important as the NanoVNA, but it you are having receive issues, this tool will tell you. How one uses it depends on what one wants to accomplish. If one has a handheld radio available, just attach the TinySA to the boat's VHF antenna cable and key the handheld radio. One should see a spike showing the power level and the frequency. If the spike is not present (assuming all settings are correct) then it can be assumed that the antenna is not working. This can also be used with the AIS antenna. One should note that this type of testing is intrusive, meaning, it will interfere with any communications in progress. Listening before keying.
TinySA also has a RF generator that is adjustable. One can connect it to the VHF antenna and test for output power without the fear of damaging your VHF radio. Again, using the handheld will help in determining if your are actually transmitting a signal or not.
Both tools are inexpensive and easy to use out of the box. There are multiple videos showing the uses of both tools. Too numerous to mention here, just do a Youtube search. Watch the videos and see if you might be able to use one, or both, of these tools.
Obviously one needs to be careful when ordering. Our friends in China are very busy cloning these tools and the clones do not work correctly. For the TinySA, go to the TinySA.org site and look for the recommended sellers. Some of the sellers also sell the NanoVNA.
Hope you find this info useful. Again, having useful tools on a boat when it comes to your communications equipment means keeping that equipment in proper working order.