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Two new toys for testing antennas

Feb 17, 2006
5,030
Lancer 27PS MCB Camp Pendleton KF6BL
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.
 

Rick D

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Jun 14, 2008
6,965
Hunter Legend 40.5 Shoreline Marina Long Beach CA
Thanks! That is exactly what I was looking for. Edit to add: just ordered it. Thanks for your recommendation and explanation.
BTW and unrelated, I think I made a mistake by joining the PAPA System. They only have one 2 meter repeater, and it's in Redlands. My ICOM 706 on the boat is 2 meter only; no 70cm. I don't like the idea of buying another radio just for the 70cm access. I have access at home, however.
 
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Feb 17, 2006
5,030
Lancer 27PS MCB Camp Pendleton KF6BL
I don't find myself using 70cm as much as 2 meters. Here at home I have a DIY 2m/70cm dipole which is made out of PVC and copper adhesive strips. I think I posted a photo once. Probably here in the SSB forum.

From where did you order your NanoVNA or TinySA?
 

Rick D

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Jun 14, 2008
6,965
Hunter Legend 40.5 Shoreline Marina Long Beach CA
I don't find myself using 70cm as much as 2 meters. Here at home I have a DIY 2m/70cm dipole which is made out of PVC and copper adhesive strips. I think I posted a photo once. Probably here in the SSB forum.

From where did you order your NanoVNA or TinySA?
I ordered the NanoVNA from Amazon. I didn't order the TinySA yet.
 
Feb 17, 2006
5,030
Lancer 27PS MCB Camp Pendleton KF6BL
OK... I was going to recommend R&L Electronics. I understand they have legitimate NanoVNA and TinySA. I think Amazon is OK. But do check it when you get it. There are ways to find out if you have a clone. R&L has a NanoVNA H4 (4" screen) that they are selling for $59.95. I purchased my TinySA from them. They come highly recommended by the TinySA.org.

 
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Mar 12, 2008
557
Jeanneau 49 DS San Pedro, CA
Boy, I’ll have to take a look at these. I’m still using an old MFJ-213.

At least you have repeaters in your area, Rick. We have a 2 meter frequency that everyone is suppose to be using. I haven’t heard anyone on it all year.
 
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Oct 2, 2008
3,409
Pearson/ 530 Strafford, NH
Just doing a little wire removal of dead lines left in the bundle behind my navigation panel. I neatened the extra wire on my Icom 802 and noticed the coil from the radio head to the box was quite long. Is that because those two parts are better separated? Could the radio performance be improved by adding a lead shield in between?
 
Feb 17, 2006
5,030
Lancer 27PS MCB Camp Pendleton KF6BL
@All U Get - Tom, the cabling between the 802 head and the transciever should be shielded. There should be no reason to add anything. But, if you are not comfortable then you can add a ground wire between the two. I doubt it will do any good, or for that matter, any harm. As Don mentioned, are you by chance having RFI in the boat or picking up interference in the radio from some other instrument in the boat?
 

CYQK

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Sep 11, 2009
481
beneteau first 42 kenora
Brian D
Have been reading your posts over the years on tronics ........thks!!!!
Ordered the Nano from R&L yesterday look forward to the test
Thks for posting this
Gary
 
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Oct 2, 2008
3,409
Pearson/ 530 Strafford, NH
@All U Get - Tom, the cabling between the 802 head and the transciever should be shielded. There should be no reason to add anything. But, if you are not comfortable then you can add a ground wire between the two. I doubt it will do any good, or for that matter, any harm. As Don mentioned, are you by chance having RFI in the boat or picking up interference in the radio from some other instrument in the boat?
Just checking how I installed the radio and if I overlooked something in the details. I do get enough static that interferes with signing in to the Southeast Cruisers net. What brought about this question was my removing wires from discontinued lines left by the PO and probably some by upgrades I hired done. Would the meter be the best way to see if I’m getting the best signal?
 
Feb 17, 2006
5,030
Lancer 27PS MCB Camp Pendleton KF6BL
If you listen to the static and it is like random noise, then I would say it is atmospheric in nature (duh, no kidding I say to myself all the while laughing at such a mundane statement). Conversely, if the static is a steady stream then the TinySA may help since it is a spectrum analyzer. Not sure if the NanoVNA would help though.

The closer to the source, the stronger the amplitude of the signal on the display. But this might not always be true. Sometimes the best thing to do is bring aboard a stand along 12v batter with enough juice to run the receiver of the radio. This should help in starting to isolate other items without affecting to power to the radio. Make sense?