RIGEXPERT AA-35 vs NANOVNA F

£300 versus £50

Three years ago I borrowed an MFJ-259 from a friend to help me with a Slim-Jim that I was building. It was a good antenna analyser, but a bit bulky and old fashioned, so when it came to investing in one for my shack, I decided to buy something more modern - a NanoVNA-F. It cost me around £50 and it covers 10k-1.5GHz, plus it does a lot more than the MFJ. Beware that there are a lot of fakes out there!

And then I got a bargain RigExpert AA-35 for a couple of hundred quid. They're normally around £300. This doesn't actually do as many things as the cheap NanoVNA, so I thought I'd do a 'real world' comparison of the two items. Is the AA-35 really worth 6 times more than the VNA (or 4x in my case)?

I should point out that the VNA can be used to do all sorts of clever things, but at this point, I have just used it to test and tune antennas in the most simple of ways. Thankfully, our local radio club (Bolton Wireless Club) is going to be hosting a "NanoVNA Tutorial Night" soon, so I hope to learn a lot more and will update this post when that happens.

Well let's start off with a look at the NanoVNA. The one I bought was the "F" model which has an attractive steel case and it comes supplied with lots of accessories including an SMA-SMA pigtail and a series of adapters to help calibration. The package came in a nice plastic carry-case, but I found an unused little Pelican Case in the shack which would protect the unit from any possible damage while rattling around the back of my car.

The NanoVNA has a 4.3" colour touch-screen which is very clear and sharp, but to be honest, it is next to useless in strong sunlight, so you have to use your hand as a sunscreen in order to take any readings when outdoors. Using 'touch' to select options isn't always reliable, but there are other ways of controlling things.

With a firmware upgrade, the unit will take measurements between 10kHz and 1.5GHz so that covers pretty much everything - more than I'll ever use, for sure! The unit is powered by an internal Lipo battery but that went kaput after a couple of years, so I now have to attach a USB PowerBank when I want to use it. I could of course order a replacement battery and solder it in place, but I just can't be bothered.

The first thing to do with a VNA is calibrate the device and that's a simple process with the supplied SHORT, OPEN & 50 Ohm dummy LOAD. I calibrated using different frequency ranges and then saved them to the five available memories...

Mem-0   1~30MHz
Mem-1   45~75MHz
Mem-2   118~148MHz
Mem-3   420~450MHz
Mem-4   450~1.5GHz

That makes it super easy to quickly choose a working range and have the highest level of accuracy. I put a Dyno-Label on the back of the device to remind me of the memory contents. Being quite a cheap device, I would still insist on a re-calibration if I was carrying out some serious work or if I’d not used the device for some time.

In any case, calibration is quick and easy - just a case of taking three readings with the supplied adapters - OPEN, SHORT, LOAD.

My test of the NanoVNA was carried out on an EFHW antenna that I had installed at home. I set it up to take readings across all the bands and this was the result.  SWR Readings are in yellow....

Switching to the RigExpert AA-35 gave me virtually the same results, so you could guess that I wasted £200, but the fact is, the AA-35 is infinitely easier to use. It's a self-contained unit in a traditional hand-held form factor. It's 'coverage' for want of a better word is only 60 kHz through 35 MHz, but that's more than enough for most people. 

If you want to be able to work with VHF and UHF antennas, then you'll have to buy one of the more expensive models in the range. The same applies if you want a Smith Chart display - having said that, you can have a Smith Chart on the AA-35 if you connect it to a PC using the USB cable and run AntScope2 software (not very practical out in the field, but not impossible).

It comes with its own carry-case, shoulder-strap and a shielded USB A-B lead with built-in ferrite.  The screen is a good size and is perfectly readable outdoors in direct sunlight. The RF connector sits on top of the device in the form of an SO-239. I'd have preferred a BNC connection instead, but it's no big deal.

The unit is conveniently powered by two AA batteries which are available everywhere, so you're unlikely to get caught out without power. They seem to last forever too - if you use good quality batteries and especially so if you opt for the amazing Energizer Ultimate Lithiums - they'll last years (well they do in my wireless CCTV cameras).

The AA-35 has a colour screen but can be set to a high-contrast monochrome scheme for those whose eyesight isn't too good. The buttons are a good size and logically laid out on the front of the unit. I prefer this to the VNA's touchscreen. In fact, I often find myself having to double or even triple the number of times I have to press the VNA's touchscreen to get it to recognise it.

The data produced by the AA-35 can be presented in a number of different ways depending on how much you want (or need) to know and whether you're a visual person (or not). Some like to see lots of numbers and some want a pretty meter. You get to choose.

The AA-35 is self-calibrating, so there's no need to ever worry about that, but, if you ever want to force a calibration (eg if you want the calibration point to be zeroed at the end of some feed line just before an antenna), then you can do that by choosing CALIBRATE in the menus and run through the usual OPEN SHORT LOAD routine and then the meter will basically ignore the feedline and take the baseline to be the very end of the feed, not the meter's SO-239.

The operational-speed of the AA-35 Zoom is quick! The various meters and sweeps work like you might expect analogue meters to work - there's very little delay and everything looks smooth and pretty darned cool.

I mentioned earlier that you can connect the analyser to a computer using the USB lead. This gives you added functionality and the ability to grab screenshots if you want to share readings with other people on a blog or email or whatever.

So overall, I much prefer to use my AA-35 when out in the field (or even out in the garden), but when I'm at home, I'm quite happy to use the cheap NanoVNA. They're both great tools!

More on the Nano after our Club's tutorial night.

73, Tom, M7MCQ.

 

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