I received my unit and as others have noted, had all kinds of trouble getting it to calibrate with the SMA loads provided. I used the N cal loads from an expensive VNA and it calibrated normally. Thus far, I have not experienced the bad charging port that others have also noted.As for now, it works as expected but have replaced the trash SMA cal/test loads with a cheap set of Type-N loads and it agrees well with my PowerAim VNA that cost 10x.I will update this review as I get some use on the unit.

If you read the product description carefully you will see this NanoVNA is made by Sysjoint, and Sysjoint happens to be one of the few manufacturers which provide actual documentation and firmware updates for the NanoVNA, as well as the nanosaver software for both Windows and Linux. The quality of this unit is impressive, it has a nice 4.3" screen, 50KHz to 3GHz range, 5000mAh lithium battery, metal case, and even the supplied USB cable is top of the line. It came with the latest firmware installed. I'm just starting to learn how to use this device but so far I'm very pleased. We will see how it holds up in my home lab long term.

The last NanoVNA I had got destroyed when a drop of water got into the power switch so I purchased this one. It is far and away much easier to use. The touch screen besides being a bit larger has a much more positive response, the old one was downright annoying. Also old one had a rocker switch on the top to select the menu and was so hard to use that I never used it, this new one has buttons on the side which are good and useful. I like that this one has metal case with the SMA connectors firmly attached to the housing so I don't have to worry about them breaking off the PCB. Also it has outrageously long battery life. The only thing I did not like is, like the old one, the display is not bright enough to use in daylight.

Used device to measure performance of 915 MHz antennas on drone radio. Antennas were very poorly tuned to explain why radio was malfunctioning. Will have much use for device to trouble shoot cheep antennas.

Fairly easy to understand without a manual. Quick and accurate after calibration. Comes in a storage box, appears to charge quickly. Will update as i use it more.

This review is for the SV4401A Vector Network analyzer. I purchased this in early August 2024 from the seller Camii Direct for $375. Since then, the price dropped lower and now is higher.This is a very sturdy unit, much larger than the tiny 'nano' type VNAs. Most people who have a nano VNAs remark on how much easier this one is to read. The unit comes with a very nice padded zippered case. Be sure to place the unit face down in the case to prevent items stored in the mesh pouch from pushing into and possibly damaging the display when you close the case. I have found plenty of room to add extra test cables and adapters in the pouch. Again, be sure to turn your unit face down into the foam before closing the case!Another huge advantage of this model is that it has just over 1,000 scan points, for better resolution than the typical 400 or so on the nano types. The scanning speed is adjustable in the settings of the unit. I have mine set pretty slow. It takes about 6 seconds to complete a scan, but you get better resolution.Also, you have eight markers total that are available to mark points on your graphs. This is exceptionally handy for marking amateur radio bands when you are scanning a multi-band antenna and looking at multiple resonance dips. Marker frequency assignments get stored when you save your calibrations. This is a super great feature. Once you do all your calibrations, as described below, you can get right to work by recalling the calibration that suits the test you want to make and get to it right away.You can break up the frequency ranges of your scans and save them as independent calibrations with completely separate marker frequency assignments that get restored when you recall the calibrations. This allows you to apply all 1000 scan points to a smaller frequency range to get better resolution. For instance, I have several calibrations for amateur radio use: 1 - 11 megahertz, 11 - 29 megahertz, 48-56 megahertz, 140 - 150 MHz, and 430 - 460 megahertz. I think you can save and load up to 9 calibration sets. I do have one wide range calibration that goes 1- 54 megahertz so that I can assess all of the resonant dips on my 160m loop antenna at once and then zoom in using one of the other calibrations with smaller frequency ranges for the best resolution.I had some problems with the unit at first and one is still ongoing but liveable. All in all the unit has been reliable and valuable for over 2 months now. That is why I knocked off one star from 5 to 4.My unit arrived with dead batteries that would not charge. See the photos and the close-up showing the percent of charge in the upper right corner as only 1%. The unit would power up using the USB charging cable but sometimes it took a couple of off-on cycles to get it to boot fully up. The red battery charge LED is on the left side of the unit and is supposed to light up steady red to indicate charging. If yours lights up solid red, as shown in my photo, then you're in good shape. In my case, this light was flashing rapidly and so faintly it was almost imperceptible, because the batteries were too discharged for the charging circuit to fully engage. Fortunately, the onboard batteries are the common type 18650 lithium ion cells, 3500mAH each, clipped into holders on the circuit board (this is actually a better design feature because it is more maintainable in the future). I pulled both of them out and their voltages measured approximately 0.42 volts each. My outboard charger refused to charge these also. I considered returning the unit as defective but after doing a little research on these batteries, I discovered that you can jump start them from another similar battery using two bare wires. See the photo. Connect them in parallel for about 20 seconds and enough charge flows into the dead battery to raise its voltage enough to allow the charging circuits to work. This revived and saved my unit.The seller was responsive and sympathetic but refused to supply new batteries. I think they were completely unaware of this problem and claimed that they were shipping out units with reduced charge for safety reasons. I thought that these batteries would never have complete capacity again after being so deeply discharged. However, they did seem to take a full charge and are holding up reasonably well. Replacements are inexpensive enough here on Amazon and I have some ready if I need them.The next problem is the touch screen. I must say first of all, that it is very nice not to need a stylus. You can do everything with your fingertips unlike with the nanoVNA types. However, this screen suffers from key bounce. When you touch a menu item or are entering numbers, it requires a very quick tap, frequently resulting in multiple taps/entries or unintended menu selections. This is very annoying and I don't see a fix for it but it works reasonably well enough to keep the unit and enjoy it for what it can do. Perhaps this can be fixed in a future firmware release (??).And speaking of firmware, this unit is manufactured by Sysjoint. The 'about' screen in the settings menu (see first pic) shows the website and support email address, but you can easily search for it yourself (see www.sysjoint.com/sv4401a.html). The product page has a support area where you can find the latest firmware, the latest manual, and a description of the changes in each firmware revision. This support being available makes all the difference in choosing this unit. My unit did not have the latest firmware but it was relatively easy to download and install using a PC. The online manual however has not kept up with the firmware releases. You need to check the website periodically for the latest releases from the manufacturer.Here are some button function shortcuts that make this unit a joy to use. These were culled from a YouTube video put out by the company:SHORTCUTS:ADD MARKER (up to 8 markers) - double click CTRLSELECT ACTIVE MARKER - hold FN button and use buttonsDELETE ACTIVE MARKER - double click FN buttonCHANGE ACTIVE MARKER FREQUENCY - scroll with buttonsENTER DISCRETE ACTIVE MARKER FREQUENCY - long press CTRL button and enter freq in pop up number padOne of the more valuable things to me that this unit does, versus a standard SWR / antenna analyzer, is measure the loss of coax. See one of my photos where I am measuring 50 ft of RG 316 coax that is wound up on a kite string winder. I use this for portable antennas. I wanted to see how much loss there was. Note how useful it is to have the eight marker points stored in the calibration so that you can read how much loss there is, band-by-band. Of course this is barely scratching the surface of all the neat things this unit can do, but this is one of the most useful things for me is identifying whether or not old coax cables or new ones even, are suitable for use.Hope this review helps you. I don't have any regrets over my purchase.