Category: HF

Reviews of the NanoVNA: An Ultra Low Cost $50 Vector Network Analyzer

A vector network analyzer (VNA) is an instrument that can be used to measure antenna or coax parameters such as SWR, impedance and loss. It can also be used to characterize and tune filters. It is a very useful tool to have if you are building and tuning home made antennas, filters or other RF circuits. For example if you are building a QFH or ADS-B antenna to use with an RTL-SDR, a VNA can help ensure that your antenna is properly tuned to the correct frequency. Compared to a standard SWR or network analyzer a VNA supplies you with phase information as well.

Until just recently, VNA's have cost roughly US$500 for a decent USB PC based unit like the miniVNA or PocketVNA, and have set people back thousands to tens of thousands of dollars for bench top units.

However, the cost of owning a VNA has now been reduced to only US$50 thanks to the NanoVNA. The open source NanoVNA project by @edy555 and ttrftech has been around since 2016, but only recently have Chinese sellers begun mass producing the unit and selling them on sites like Aliexpress, eBay and now Amazon. We note that it seems that there are some sellers selling them without shielding, so it might be worth double checking the listing to see if they mention that. All the listings we've seen seem to come with simple calibration kits as well.

The NanoVNA: A $50 Vector Network Analyzer
The NanoVNA: A $50 Vector Network Analyzer

The NanoVNA is a small credit card sized VNA. It has a built in LCD screen that can be used to display graphs directly, or it can also be connected to a PC and the graphs viewed via the NanoVNA Windows software. When purchasing you can opt to include a small battery for portable operation for a few dollars extra. The frequency range is from 50 kHz to 900 MHz, although you should note that above 300 MHz dynamic range performance is reduced.

Over on YouTube several hams and radio enthusiasts have recently uploaded videos demonstrating and reviewing the NanoVNA. The overall consensus is that the unit is accurate and works well. For additional support there is forum available at Groups.IO.

Below YouTube user IMSAI Guy reviews the NanoVNA. Check out IMSAI Guy's other videos too as he has several where he tests the NanoVNA on difference filters and antennas, and checks the accuracy.

#350 NanoVNA Vector Network analyzer 900MHz VNA for $50

Below is YouTube user joe smith's review. He also has two other NanoVNA videos on his channel where he shows how to use the NanoVNA to measure antenna impedance, and how to use the NanoVNA to create SPICE models for simulation.

The NanoVNA, a beginners guide to the Vector Network Analyzer

Finally YouTube user Oli gives another overview. Please note that the following video is in Polish, but YouTube captions can be set to English.

NanoVNA - omówienie, kalibracja, pomiar anteny i filtra [english subtitles]

We've also seen several recent text reviews:

NanoVNA - A short review. In this review nuclearrambo shows off the calibration kit, and shows a practical measurements of a directional coupler and 137 MHz QFH antenna.

NanoVNA compared with a Keysight fieldfox N9952A. Here nuclearrambo provides a comparison between the $50 NanoVNA and the $40,000+ Keysight FieldFox N9962A.

The NanoVNA, a real VNA at less than 48 €!. A review written in French, but Google Translate can be used. In this review David Alloza compares the NanoVNA against an Agilent E5062A benchtop VNA, and results look comparable.

WebWSPR: A Browser Based WSPR Decoder and Visualization Tool

A few days ago we posted about [dj0abr / Radio Electronics'] WebSDR software for QO-100. Having looked through his GitHub we've seen that he also has an a similar browser based server tool called WebWSPR for WSPR decoding and visualization (click with WebWSPR link) which was released earlier this year.

WSPR is an amateur radio digital HF mode designed to be decodable even if the signal is transmitted with very low power and is very weak. It can be used to help determine HF radio propagation conditions as WSPR reception reports are typically automatically uploaded to wsprnet. In the past we have been able to receive WSPR and similar modes like FT8 with our RTL-SDR V3 running in direct sampling mode.

Like his QO-100 WebSDR software, WebWSPR is designed to run on a single board computer like a Raspberry Pi or any Linux machine. It serves a web page that shows the WSPR waterfall, decoded data and has various WSPR related control options. The web page can be accessed remotely from any machine on the same network as the server, or could be put on the internet with port forwarding and a hostname service like noip.

A ready to use Raspberry Pi image for WebWSPR is available here (does not seem to support the latest Pi4 or 3B+ however). Manual installation instructions can be found here. The code is all open source and available on GitHub.

The software appears to take input from the soundcard for standard hardware receivers, but it should be possible to pipe audio from an RTL-SDR into pulseaudio, which the software can then use. The instructions from our RTL-SDR V3 WSJT-X tutorial may help.

WebWSPR Browser Screenshot
WebWSPR Browser Screenshot

Fenu Radio Reviews the Airspy HF+ Discovery

The Airspy HF+ Discovery is a smaller, lighter and improved version of the Airspy HF+ which is an HF and VHF SDR with very high dynamic range. The Discovery builds on the HF+ by adding low loss preselectors. This increases the dynamic range even further, and allows the Discovery to compete with some very high end (and much more expensive) SDRs.

Currently the Airspy HF+ Discovery is available for preorder for USD$169. There have been a few delays in getting the unit out, but it appears that the Airspy team will begin shipping very soon.

Over on his blog, radio product reviewer Fenu-Radio has received an Airspy HF+ Discovery, and has given it an in depth review and put it through several real world tests. Fenu-Radio notes that while the initial prototype unit that he received had some issues with overload above 19 MHz, the latest production version has completely remedied this, resulting in impressive performance that competes favorably with the high end USD$2000 Winradio G33DDC software defined radio.

In the review Fenu-Radio compares the Discovery against the G33DDC and finds absolutely no difference in performance between the two. In the review he's also uploaded several audio comparison samples so that you can hear for yourself how identical the two radios are.

Fenu-Radio's Airspy HF+ Discovery Review Unit
Fenu-Radio's Airspy HF+ Discovery Review Unit

SignalsEverywhere: Creating a DIY Upconverter with a HackRF and RF Mixer

Over on YouTube Corrosive from the SignalsEverywhere channel has uploaded a new video showing us how you can make a DIY upconverter using a HackRF as a signal source and a cheap $10 RF Mixer. An upconverter converts lower frequencies into higher frequencies. For example, an upconverter is commonly used to convert HF signals into VHF, so that VHF/UHF only SDRs can receive HF.

In the video he uses the HackRF as a local oscillator source, a cheap RF mixer on a breakout board, and an Airspy as the receiver. In most circumstances if you needed and upconverter you'd just purchase one like the Ham-it-up, or the Spyverter for ~$40. However the interesting advantage of using a versatile signal generator like the HackRF is that it results in an upconverter that can upconvert HF to almost any frequency. Even without any filtering (which is recommended to remove signal images), Corrosive fings that he has excellent HF reception.

This video is an excellent way to learn about how upconverters work.

HackRF and RF Mixer = DIY RTL SDR Up-converter | Basics of the Passive ADE Mixer


LimeRFE WSPR Tests

The LimeRFE is a power amplifier and filter bank solution designed for the low cost TX capable LimeSDR software defined radios. It has multiple bands from HF all the way up to 3.5 GHz, and is capable of putting out about 2W on the HF bands. Currently LimeRFE is crowdfunding over on CrowdSupply with a cost of US$599 or alternatively there is now a cheaper unit for US$449 without support for the cellular bands. The campaign is active for 4 more days from the time of this post, and after that the price is due to rise by another US$100.

The team at LimeMicro sent a unit to Daniel Estévez (EA4GPZ) for testing, and he has recently posted about his results and thoughts when using the LimeRFE for WSPR transmission with a 15m long wire antenna. Daniel connected his LimeRFE to his LimeSDR and used WSJT-X piped into SDRAngel via Pulseaudio to transmit WSPR on the 10m band. He notes that for lower bands, the LimeRFE will still need additional low pass filtering to attenuate harmonics. SDRAngel cannot yet control the LimeRFE so he also created a simple Python script for this purpose.

Unfortunately Daniel's unit only achieved 25dBm instead of the advertised 33dB, but in LimeMicro's post they note that they believe that this is due to shipping damage. However, even with only 0.3W power, Daniel's transmissions from Madrid were able to be picked up in the Canary Islands, Netherlands and Northern England.

WSPR Range with a LimeRFE (reduced 0.3W output)
WSPR Range with a LimeRFE (reduced 0.3W output)

YouTube Review of the RS-918: A Chinese Clone of a Clone of the mcHF SDR

Over on YouTube Kevin Loughin has uploaded a video reviewing the "Recent RS-918" which is a Chinese clone of the popular mcHF open source SDR transceiver made by Chris (M0NKA). The mcHF is a well known small and inexpensive home brewed open source HF QRP SDR that was started back in 2013. It's sold either as a kit for 236.82 GBP (US$287), or with metal enclosure at 292.78 GBP (US$354). The kit comes with SMD components already soldered, but you still need to solder the through hole components and assemble it into the enclosure. The RS-918 clone can be found fully assembled as a ready to use product on eBay for approximately US$400.

As the "Recent RS-918" is a commercial Chinese clone of an open source project that has restrictions against commercial use, it goes against the spirit and legality of the licence imposed by the original creator. So based on that Kevin cannot recommend the RS-918 SDR. However, from his review Kevin notes that apart from some burning hot areas on the metal after transmitting, the SDR itself works and has a nice minimal design. The design appears to be based on an older version of the mcHF, so the latest upgrades are not available.

Kevin's review just overviews the RS-918 and doesn't go into depth reviewing the radio. For the rest of his video Kevin discusses the lineage of the RS-918, noting that it is actually a clone of the Ailunce HS1, which in turn is a clone of the mcHF. He then goes on to discuss the mcHF itself, noting that we should support all the hard work that Chris has put in (and continues to put in) to the original mcHF rather than these immoral clones.

Ham Radio - The RS-918 clone of a clone of an outstanding open source SDR transceiver, the mcHF.

SignalsEverywhere: Improving HF Reception with Impedance Matching

This week on the SignalsEverywhere YouTube channel host Corrosive explores why impedance matching matters when trying to obtain the best reception possible. To do this he reviews the NooElec 1:9 Balun, which is designed to convert the (roughly) 450 Ohm impedance of a long wire antenna or ladder line dipole back down to 50 Ohms, which is the standard impedance that an SDR expects. Small amounts of impedance mismatch are negligible for RX, but larger mismatches can result in poor reception.

SDR Nooelec 1:9 Balun | Why Impedance Matters in Radio

Homebrew SDR Transceiver for HF Operation

Traditionally when we think about Software-Defined Radio we’re thinking about little USB adapters that unlock a world of radio in the palm of our hands. This is done by allowing us to directly sample the IQ data from the mixer within the SDR.

However, this isn’t the only way to experience Software-Defined Radio. Ham Radio operator [Charlie Morris] has uploaded a 10 part series on YouTube explaining how he implemented his own HF transceiver, including custom software. Some of the components such as the amplifier and filters are built completely from scratch, other components use a little DSP magic from a “Teensy” microcontroller. 

Charlie actually samples the I and Q data in a similar way that today’s SDRs do and even implemented the transmit side of the radio so he can make contact with other radio operators around the world, and man… it sounds good!

You can find a complete playlist from Charlie with well-explained videos that go over his entire process from planning, schematics, layout and final operation. The channel appears to be quite active and will surely continue to pump out amazing content.

Homebrew SDR SSB Rig – Part 9 First On-Air QSO!