Many thanks to SWLing Post contributor, Mario Filippi (N2HUN), who shares the following guest post:
Author’s Airspy HF+ Discovery (small black box to the left of the laptop)
A Short Review of the Airspy HF+ Discovery SDR
by Mario Filippi (N2HUN)
I recently purchased an AirSpy HF+ Discovery. As a SWL for over 60 years who’s owned many shortwave radios by manufacturers such as Drake, Yaesu, Icom, Zenith, Kenwood, Panasonic, Sony, Radio Shack, Grundig, CountyComm, MFJ, Sears, AOR and have used a number of different SDRs such as the RTL-SDR.com, HackRF, NooElec and many other rudimentary inexpensive first generation SDR dongles, I feel the AirSpy was an excellent choice. It cost $169 plus shipping.
For LW/MW/HF reception, I use a 30’ ground mounted vertical with about 50 buried radials in different stages of decomposition hihi. For VHF, a roof mounted 2m/70cm SlimJim antenna is used, but I haven’t done much listening in that portion of the spectrum yet except for occasional foray into the aero, 2m ham, NOAA satellite and public service bands. Note that the AirSpy also covers 60 – 260MHz.
An older Dell Inspiron laptop and SDR# are used in conjunction with the AirSpy. For decoding, MultiPSK, FLDigi, MTTY, Yand (for NAVTEX), along with VB cable are the accompanying software to make the digital modes intelligible.
So far I’ve logged a few local LF aeronautical beacons and some DGPS beacons on longwave but will be in a better position to judge its performance when winter sets in. As for the medium (520 – 1710 kHz) wave AM broadcast band, the AirSpy easily brings in both local stations during daytime and distant stations at night with no adjacent channel interference whatsoever. Even low powered community Emergency Alert Stations in the 1600 – 1710 kHz portion of the band can be heard daily from this QTH. A rotatable loop would certainly improve reception though.
As for shortwave listening the AirSpy HF+Discovery is, in my opinion, great for listening to both shortwave broadcasts and utility stations though I tend to concentrate on UTES mostly such as VOLMET, WEFAX, RTTY (the few that remain unencrypted), CW marker stations (e.g. XSG and XSQ from China) NAVTEX (519 kHz), aero/maritime SSB, time signal stations (WWV, CHU) and many of the other esoteric digital utility signals populating the band. As for SW broadcast stations, WRMI, Radio Exterior, RFI, R. Marti, BBC, WWCR and Radio Algerienne, to mention a few have been received. The Frequency Manager (memory storage) in SDR# has quickly filled up with intercepts using the AirSpy.
As a ham and CB operator (yes, the two can mutually coexist in the same human body), I’ve found the AirSpy HF+ Discovery to be a trouper on all the HF ham and CB bands. One of my favorite hangouts is the 28.100 – 28.300 MHz slice of 10m where domestic and international low power CW beacons transmit their callsigns (and at times their grid squares and power output) into the ionosphere and achieve great distances. Recently, beacons from 5, 6 and 7 land in the US along with DX prefixes ED4, PY4 and XE1 were logged. If you’re into 10m FM operation you can also tune the AirSpy to hear local and distant repeaters on 29.62 – 29.68 MHz. When the band is open, .62 and .64 seem to be the most active here in Central NJ.
If you’re a CB (aptly named the Citizen’s Band) op, the AirSpy HF+ Discovery does a stellar job on Channels 1 – 40 which is especially exciting when the band’s open. While domestic (USA) CB’ers are limited to frequencies from 26.965 – 27.405 MHz you’ll nonetheless hear DX ops below our (USA) channel 1 and above channel 40 conversing in French, Spanish and German in LSB/USB. Add to this mix the fact that the FCC dropped the 150 mile limit for US ops a few years back and now the advent of the FM mode operation in the US, you’ll find the AirSpy won’t disappoint. In my opinion the AirSpy HF+Discovery was an excellent choice and I’m more than satisfied with its performance.
In the matter of honesty and full disclosure, I purchased the AirSpy HF+ Discovery completely on my own in an effort to upgrade my station. My choice was based on information gathered from the Internet and YouTube video reviews. The performance of this receiver was based on my experience using the vertical antenna described earlier, the hours spent at my QTH (location) listening to stations of interest to me and my six decades experience as a SWL. No test equipment to assess sensitivity, selectivity or other empirical methods to measure performance was used. That information can be found on the Airspy website. The main purpose of this article was to craft a rudimentary review for those interested with the caveat that reception will vary depending on many factors such as location, antenna, ionospheric conditions, feedline quality, computer/software variations, QRN, QRM, and operator experience. The results presented in this article are typical for my location; others may experience different results. Thanks very much.
Thank you Don, Price, Henry, RobRich, and Robert for all the kind follow up comments.
Henry, it’s been a few years since I performed an IF alignment. Most times I used a signal generator and a voltmeter, sometimes an o’scope to peak an IF. It varied depending on what the service manual directed you to do.
As for using the Airspy for the other parameters you mentioned, I haven’t tried those. A benchtop SA will have advantages over using an Airspy such as variable Resolution Bandwidth selection and a Tracking Generator (usually an option that costs extra but very convenient for testing filters ). Most importantly, SAs usually have a maximum input signal stated in their specs to avoid damage from signal overload.
Hi Mario,
I am also fan of Airspy receivers. me have 2x Discovery + Airspy R2 too.
Me found excellent information book written by Paolo IZ1MLL see here, free download.
https://airspy.com/downloads/SDRSharp_Big_Book_v5.3.pdf
Antennas in use are hula loop home made, End Fed 49:1 home made and of course Discone for VHF/UHF
VY 73″ MNI DXs
Ladislav OK1UNL
TL;DR: buy a (nano)VNA if you want to test filters. (Too) long version:
An SDR has no concept of RBW: this is set entirely in whatever software you’re using.
Rather, the advantage of a TG with an SA is that they should be able to work with each other (that is, feed the SA’s tracking to the TG) and real SAs have an output just for that, assuming they really are separate devices like the RF Explorer and Signal Hound product lines. (All of that said, if need a SNA, why not buy a full-fledged VNA instead, with a good NanoVNA still under $100!)
A huge difference between a cheap SDR (and something the SDRPlay people have worked on in later models) is that an SA is, by definition, a measuring receiver where you can display absolute value (V or W) on the input; neither the Realtek nor Airspy nor (I suspect) the majority of them are built for this, and its part of what you’re paying for when you get a real SA (the calilbration, more bits, etc).
Oh, FWIW, I bought an Airspy (along with some YouLoops) as well since it seems superior for (V)LF to SDRPlay along with very crowded bands; too bad my local noise level pretty much negates much listening locally. 🙁
Nice review. I have this SDR and several others. I love its small size for portability and convenience. I wish it got up into the 1.5 GHz range for satellite but I have others for that. I would also prefer a USB-C connector instead of Micro, but those are just niggling issues. Performance is what counts and it is superb in that case.
Very nice review. The Airspy has become my favorite SDR and is by far the best travel SDR, even if it does take two to record the entire MW band. The variety of bandwidths makes it great for making utility spectrum recordings for later analysis. I have to two and will probably buy a third.
Mario:
I enjoyed your review of the Airspy HF+ Discovery. I have owned and used one for about 18 months , and I am still amazed at it’s performance. The SDR# (SDR Sharp) software that I use with the Airspy is, I think, specifically written for the Airspy SDR family. Both SDR# and the SRD# manual are frequently updated and are extremely well done. There is a moderately large and quite active Airspy user’s group and many very powerful and trivially easy to install plug ins are available, I own several other SDR’s, and my impression is that the Airspy HF+ Discovery is more than competitive in the below 30 MHz bands that I play around with. The Airspy SDRs and SDR# are built for use with Windows x86 systems, but I use the SDR HF+ and SDR# with Parallels (Windows 10) on a MacBookPro (macOS Catalina) with no problems what so ever.
Very interesting review – thank you Mario.
I have an “odd” question about using an SDR:
can the spectrum monitor like capabilities of an SDR be used to do a “super alignment” of an old radios Intermediate Frequency?
Can you use an SDR to look at the “Passband” before and after filters to “tweak” the alignment to maximum sensitivity?
Can you measure “Steepness” of the left and right hand skirts of filters, and so forth?
You can use a SDR as a spectrum analyzer.
Spektrum supports the affordable RTL-SDR dongles.
https://github.com/pavels/spektrum
QSpectrumAnalzyer supports various SDRs via SoapSDR and other backends.
https://github.com/xmikos/qspectrumanalyzer
That said, you might be interested in the tinySA if looking for a standalone SA with PC connectivity.
https://www.tinysa.org/wiki/
I have used my SDRs (the HF+ and the older SDRPlay RSP1a) in retro tabletop alignment, particularly to get the 455 KHz I.F. frequency dead on. I wind a little “sniffer” air coil (maybe 8 turns x 1/2 inch diameter) at the end of a short piece of coax. Plug the coax into the antenna port of the SDR. Put the sniffer coil near the I.F. strip or the signal of interest and you are in business.
Great approach on this review, Mario – real-world experience always trumps lab specs. I have the same SDR (among others) and agree with your assessment. It is truly amazing how far these relatively inexpensive SDRs have come. I am still amazed at what you can do with the original $10 dongle SDRs, and these Airspy receivers have amazing range and options, not to mention how advanced and capable the software is these days. Cheers!