HFU HF Underground
Technical Topics => Equipment => Topic started by: Matt285 on February 26, 2020, 1949 UTC
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So I purchased a NanoVNA, but I cant find a simple way to just check SWR with it. I went thru the various calibration steps, but I'm looking to make it a bit simpler. The unit is capable of a lot of features I don't particularly need use of for at this time. Any advise on the more basic aspects of this unit. If anyone would like to explain to me like I'm a 5 year old, I won't take any offense to it. Thanks
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It's not the best device for that. :)
Your best bet is probably on YouTube. There are many videos -- just search for 'nanovna' and you'll find quite a few. A couple have complete a walk-through of the device, etc.
I can recommend the RigExpert analyzers. They're on Amazon and you can also find them at any ham radio store. They're not cheap however. HF model is $250-ish and the AA-600 (which covers DC-600 Mhz) is about $600. Sometimes you can find them used on E-Bay for a good price.
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I have a RigExpert Zero which is a bit less expensive at $79. No display and you need to put it in your own case, but hey if you're cheap like me... :)
https://www.amazon.com/gp/product/B077B9D18K/ref=ppx_yo_dt_b_detailpage_o00_s01?tag=blackcatsyste-20
More info: https://www.hfunderground.com/board/index.php/topic,49903.0.html
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Got my NanoVNA today. Haven't had time to play with it yet, but here's a video on how to use it to measure SWR
https://www.youtube.com/watch?v=_drx7ORUDWI (https://www.youtube.com/watch?v=_drx7ORUDWI)
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I found that running the software NanoVNA Saver was a big help in simplifying the use of this device. Not a big fan of tiny touch screens even though my eyesight is very good. You can customize the plots on the screen and enter frequency limits easier.
https://github.com/mihtjel/nanovna-saver/releases/tag/v0.2.2
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FWIW, this is a pretty good deal. FYI, the SARK100 has shown to be a less accurate when compared to RigExpert (and other) analyzers. The accuracy difference is still within tolerances and shouldn't stop someone from buying it. The cost difference is pretty substantial.
https://www.amazon.com/Antenna-Analyzer-1-60MHz-Shortwave-Measurement/dp/B07PGVDGL2
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Yes. I've seen some of the videos where the software interface is being used. I imagine it would be easier. There may even be some drop down help functions as well.
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I don't have any experience with the nanoVNA but working from general VNA principles you can:
1) connect your antenna to port 1 and then measure S11 or
2) connect the antenna to port 2 and measure S22.
The two would be equivalent in this case. Just don't connect your antenna to port 1 and try to measure S22. That's not right.
The lower the result (more negative) in return loss, the better.
Here is a conversion chart between return loss and VSWR (ignore the negative sign in the return loss you read from the VNA): https://www.amphenolrf.com/vswr-conversion-chart/ (https://www.amphenolrf.com/vswr-conversion-chart/)
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Thanks for all the feedback. I'm certain its a good product for the price,. I just need to figure out how to simplify it a bit. In the right hands im sure its very useful. I currently don't have those hands.
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If EXACT accuracy is not required at this time, then don't worry about calibrating it yet. The unit comes calibrated across the entire range of the VNA.
I assume you do have the required adapters to connect your antenna.
Connect antenna to CH0.
Go to the menu
Select DISPLAY. Select TRACE and turn off all traces except trace 1.
In the menu, select STIMULUS and set the START frequency of the range you want to measure. For example, if you want to adjust your aerial for 440 Mhz, set the START at 400M. Repeat for STOP. Say, 500M.
If you want, you can calibrate it now and save it as a preset.
Back in the menu, select DISPLAY-FORMAT and SWR.
Use the switch at the top to move the marker to the bottom of the SWR curve to read the SWR ratio.
That's it.
You can narrow the range if required.
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Thanks a lot Brian. That sounds pretty straight forward. I left the unit in my office at work. I will try to do some test tomorrow with an HT antenna and a 2M mag mount . I'll let you know how it goes.
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I will try to do some test tomorrow with an HT antenna and a 2M mag mount .
If you are uninitiated to this sort of thing, you might be surprised at how much the VSWR/return loss/input impedance changes as your hands and body get close to the antenna, how it changes as you take the antenna off the car and then put it back on again, or as you move the antenna location, etc.
Also, you may be surprised to know that HT antennas and mobile whips are not perfect loads and the impedance changes a lot between 144 and 148 MHz.
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Yep with portable antennas they can be quite funny. For ideal results you need to hold it away from your body and make sure the rubber duck is vertical (to simulate real world use.)
Of all the two-way radio antennas I've tested, only a handful are constructed/designed well -- and that actually have usable SWR values for their assigned band.