Category: Reviews

Testing out the New Airspy HF+ Preselector

The Airspy team have recently been working on a preselector retrofit product for their HF+. The Airspy HF+ already has excellent dynamic range and sensitivity, but by adding a preselector they seek to improve performance enough to claim that the HF+ is as good as or even better than much more pricey SDRs like the Perseus by achieving dynamic range figures of more than 105 dBm.

A preselector is a filter or bank of filters that attenuates out of band signals. This is useful as radios can desensitize if an unwanted signal comes in too strongly. For example, if you are tuned to the 20m band, but there is a very strong MW signal, the SNR of your desired 20m band signal might be reduced. Radios with a natural high dynamic range design like the Airspy HF+ are less affected by this problem, but for the strongest of signals use of a preselector can still help.

The Airspy HF+ preselector needs to be soldered directly onto the HF+'s PCB, and once installed it automatically switches bands using GPIO expansion ports controlled automatically via tuning in SDR#, so no external switching is required.

The expected pricing of the HF+ preselector is US$49, and it will be ready for sale in a few weeks.

Measurements

We received a prototype of the filter a few days ago and have been testing it out. From measurements on a VNA, we found that the preselector features four bands of operation:

  • 0 - 5.2 MHz
  • 5.2 - 10 MHz
  • 10 - 17 MHz
  • 17 - 30 MHz

Airspy have also provided us with a block diagram schematic which we show below.

HF+ Preselector Schematic
HF+ Preselector Schematic

Insertion loss appears to be mostly below 3 dB with fairly steep skirts especially on the lower side. The top three filters do an excellent job at blocking out the broadcast AM band. Below are some VNA plots that show the filter responses.

VNA_180628_175816
VNA_180628_175907
VNA_180628_180008
VNA_180628_180057

Installation

The preselector comes in a small 3.2 x 1.7 cm sized PCB that is fully covered with a metal shielding can. To install it you need to carefully solder it onto the HF+ PCB. This can be a little tricky since the pads are so small, but if you're experienced with soldering it shouldn't be an issue.

  • First you need to open the HF+ and remove R3 from the HF+ PCB, which is a zero ohm resistor.
  • The preselector PCB can then be positioned and the two IN and OUT pads soldered in place.
  • Then you'll also need to connect the power and 2x GPIO lines to the preselector using wires.
  • Now you need to bridge the two shielding CANs with a thick bit of wire. We simply used two cuts of copper solder braid to do this.
  • Finally is also recommended to update the HF+ firmware to the latest version and download the latest version of SDR#.

Once soldered in place the preselector is ready to use, and the HF+ cover can be put back on. It is expected that the commercially sold versions of the preselector will come with detailed installation instructions. 

In the first photo below we removed the shield to see what was inside, and the second photo shows it installed on the HF+ PCB.

hf+presel_PCB
hf+presel_installed2

Using it on a RTL-SDR V3

Whilst the preselector is designed for the Airspy HF+, there's no reason why it couldn't also be retrofitted onto other SDRs, such as our RTL-SDR V3, for use in improving direct sampling mode performance.

The V3 has spare GPIO ports that can be used to control the filter, and 5V for powering the filter could be tapped off the PCB as well. Currently we're considering making a breakout PCB for the filter than might aide with this.

We did a quick test with the preselector connected to the RTL-SDR V3 running in direct sampling mode, and as expected performance is much better, especially above 5 MHz once the second filter kicks in. This is because the second, third and fourth filters all heavily attenuate the MW broadcast AM band, which is the main source of overload issues on HF.

The following screenshots show how much the filter was able to reduce the signal strength of AM broadcast when the second 5.2 - 10 MHz filter was turned on. This reduction was enough to prevent overload on all the higher bands.

Preselector OFF

Preselector OFF

Preselector ON

Preselector ON

Preselector OFF

Preselector OFF

Preselector ON

Preselector ON

HF+ Results

For the HF+ we tested by injecting a strong signal into two HF+ SDRs, one with the filter installed and the other without. The HF+ with the filter was routinely able to withstand much higher signal powers without any signs of overload occurring, and no degradation due to insertion loss was observed.

The screenshots below show an experiment with a weak desired signal injected at 14.2 MHz, and a strong unwanted signal being injected at 1.5 MHz. With the unwanted signal at 5 dBm, the filtered HF+ showed no signs of overload, whilst the unfiltered HF+ had the AGC kick in to increase the front end attenuation, reducing the signal strength by about 20 dB and raising the noise floor.

Filtered HF+

Filtered HF+

Unfiltered HF+

Unfiltered HF+

Other Reviews

Other reviewers have also received the preselector and have been testing it. Fenu radio has uploaded a short review, and plans to write more in the future. He's also made his HF+ with preselector available for public use via SpyServer (details in his post). In the video below Leif SM5BSZ reviews the preselector and runs through several tests while comparing it against the Perseus. His results seem to show that the Persues gets a +25 dBm IP3, whilst the HF+ with the latest firmware and preselector is able to obtain a respectable +10 dBm IP3. 

hfpluspresel2

Conclusion

For most people, the dynamic range of the HF+ is probably already more than enough, but if you are receiving very strong signals, the preselector can help get you get more performance out of the HF+. Of course the preselector cannot help if you have strong signals within the filter bands.

If you're looking to get the most out of your HF+ then the filter at only $49 is a pretty good deal. Just take note that you'll need to open the HF+ and be comfortable with soldering onto the PCB. 

Testing out the New Airspy HF+ Preselector

The Airspy team have recently been working on a preselector retrofit product for their HF+. The Airspy HF+ already has excellent dynamic range and sensitivity, but by adding a preselector they seek to improve performance enough to claim that the HF+ is as good as or even better than much more pricey SDRs like the Perseus by achieving dynamic range figures of more than 105 dBm.

A preselector is a filter or bank of filters that attenuates out of band signals. This is useful as radios can desensitize if an unwanted signal comes in too strongly. For example, if you are tuned to the 20m band, but there is a very strong MW signal, the SNR of your desired 20m band signal might be reduced. Radios with a natural high dynamic range design like the Airspy HF+ are less affected by this problem, but for the strongest of signals use of a preselector can still help.

The Airspy HF+ preselector needs to be soldered directly onto the HF+'s PCB, and once installed it automatically switches bands using GPIO expansion ports controlled automatically via tuning in SDR#, so no external switching is required.

The expected pricing of the HF+ preselector is US$49, and it will be ready for sale in a few weeks.

Measurements

We received a prototype of the filter a few days ago and have been testing it out. From measurements on a VNA, we found that the preselector features four bands of operation:

  • 0 - 5.2 MHz
  • 5.2 - 10 MHz
  • 10 - 17 MHz
  • 17 - 30 MHz

Airspy have also provided us with a block diagram schematic which we show below.

HF+ Preselector Schematic
HF+ Preselector Schematic

Insertion loss appears to be mostly below 3 dB with fairly steep skirts especially on the lower side. The top three filters do an excellent job at blocking out the broadcast AM band. Below are some VNA plots that show the filter responses.

VNA_180628_175816
VNA_180628_175907
VNA_180628_180008
VNA_180628_180057

Installation

The preselector comes in a small 3.2 x 1.7 cm sized PCB that is fully covered with a metal shielding can. To install it you need to carefully solder it onto the HF+ PCB. This can be a little tricky since the pads are so small, but if you're experienced with soldering it shouldn't be an issue.

  • First you need to open the HF+ and remove R3 from the HF+ PCB, which is a zero ohm resistor.
  • The preselector PCB can then be positioned and the two IN and OUT pads soldered in place.
  • Then you'll also need to connect the power and 2x GPIO lines to the preselector using wires.
  • Now you need to bridge the two shielding CANs with a thick bit of wire. We simply used two cuts of copper solder braid to do this.
  • Finally is also recommended to update the HF+ firmware to the latest version and download the latest version of SDR#.

Once soldered in place the preselector is ready to use, and the HF+ cover can be put back on. It is expected that the commercially sold versions of the preselector will come with detailed installation instructions. 

In the first photo below we removed the shield to see what was inside, and the second photo shows it installed on the HF+ PCB.

hf+presel_PCB
hf+presel_installed2

Using it on a RTL-SDR V3

Whilst the preselector is designed for the Airspy HF+, there's no reason why it couldn't also be retrofitted onto other SDRs, such as our RTL-SDR V3, for use in improving direct sampling mode performance.

The V3 has spare GPIO ports that can be used to control the filter, and 5V for powering the filter could be tapped off the PCB as well. Currently we're considering making a breakout PCB for the filter than might aide with this.

We did a quick test with the preselector connected to the RTL-SDR V3 running in direct sampling mode, and as expected performance is much better, especially above 5 MHz once the second filter kicks in. This is because the second, third and fourth filters all heavily attenuate the MW broadcast AM band, which is the main source of overload issues on HF.

The following screenshots show how much the filter was able to reduce the signal strength of AM broadcast when the second 5.2 - 10 MHz filter was turned on. This reduction was enough to prevent overload on all the higher bands.

Preselector OFF

Preselector OFF

Preselector ON

Preselector ON

Preselector OFF

Preselector OFF

Preselector ON

Preselector ON

HF+ Results

For the HF+ we tested by injecting a strong signal into two HF+ SDRs, one with the filter installed and the other without. The HF+ with the filter was routinely able to withstand much higher signal powers without any signs of overload occurring, and no degradation due to insertion loss was observed.

The screenshots below show an experiment with a weak desired signal injected at 14.2 MHz, and a strong unwanted signal being injected at 1.5 MHz. With the unwanted signal at 5 dBm, the filtered HF+ showed no signs of overload, whilst the unfiltered HF+ had the AGC kick in to increase the front end attenuation, reducing the signal strength by about 20 dB and raising the noise floor.

Filtered HF+

Filtered HF+

Unfiltered HF+

Unfiltered HF+

Other Reviews

Other reviewers have also received the preselector and have been testing it. Fenu radio has uploaded a short review, and plans to write more in the future. He's also made his HF+ with preselector available for public use via SpyServer (details in his post). In the video below Leif SM5BSZ reviews the preselector and runs through several tests while comparing it against the Perseus. His results seem to show that the Persues gets a +25 dBm IP3, whilst the HF+ with the latest firmware and preselector is able to obtain a respectable +10 dBm IP3. 

hfpluspresel2

Conclusion

For most people, the dynamic range of the HF+ is probably already more than enough, but if you are receiving very strong signals, the preselector can help get you get more performance out of the HF+. Of course the preselector cannot help if you have strong signals within the filter bands.

If you're looking to get the most out of your HF+ then the filter at only $49 is a pretty good deal. Just take note that you'll need to open the HF+ and be comfortable with soldering onto the PCB. 

A Review of the HackRF PortaPack (With Havoc Firmware)

The PortaPack is a US$220 add-on for the HackRF software defined radio (HackRF + PortaPack + Accessory Amazon bundle) which allows you to go portable with the HackRF and a battery pack. It features a small touchscreen LCD and an iPod like control wheel that is used to control custom HackRF firmware which includes an audio receiver, several built in digital decoders and transmitters too. With the PortaPack no PC is required to receive or transmit with the HackRF.

Of course as you are fixed to custom firmware, it's not possible to run any software that has already been developed for Windows or Linux systems in the past. The official firmware created by the PortaPack developer Jared Boone has several decoders and transmitters built into it, but the third party 'Havoc' firmware by 'furrtek' is really what you'll want to use with it since it contains many more decoders and transmit options.

As of the time of this post the currently available decoders and transmit options can be seen in the screenshots below. The ones in green are almost fully implemented, the ones in yellow are working with some features missing, and the ones in grey are planned to be implemented in the future. Note that for the transmitter options, there are some there that could really land you in trouble with the law so be very careful to exercise caution and only transmit what you are legally allowed to.

Some screenshots from the HackRF Portapack Havok Firmware
Some screenshots from the HackRF Portapack Havoc Firmware
More Havok firmware screenshots from the GitHub page.
More Havoc firmware screenshots from the GitHub page.

Although the PortaPack was released several years ago we never did a review on it as the firmware was not developed very far beyond listening to audio and implementing a few transmitters. But over time the Havok firmware, as well as the official firmware has been developed further, opening up many new interesting applications for the PortaPack.

Doing a replay attack on a wireless keyfob using the Portapack.
Doing a replay attack on a wireless keyfob using the PortaPack.

Testing the PortaPack with the Havoc Firmware

Capture and Replay

One of the best things about the PortaPack is that it makes capture and replay of wireless signals like those from ISM band remote controls extremely easy. To create a capture we just need to enter the "Capture" menu, set the frequency of the remote key, press the red 'R' Record button and then press the key on the remote. Then stop the recording to save it to the SD Card.

Now you can go into the Replay menu, select the file that you just recorded and hit play. The exact same signal will be transmitted over the air, effectively replacing your remote key.

We tested this using a simple remote alarm system and it worked flawlessly first time. The video below shows how easy the whole process is.

Portapack Replay

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LimeSDR Mini Unboxing and Initial Review

The LimeSDR Mini has now started shipping out to backers, and we received our unit just last week. The LimeSDR Mini is the smaller version of the full sized LimeSDR which was released early last year in 2017. The standard LimeSDR has a frequency range of 100 kHz – 3.8 GHz, bandwidth of up to 61.44 MHz, 12-bit ADC and 2 x 2 RX/TX channels. In comparison the new LimeSDR mini has a slightly restricted frequency range of 10 MHz – 3.5 GHz, and half the maximum bandwidth at 30.72 MHz. The mini also only has 1 x 1 TX/RX channels. The price is however much less coming in at US$139 for the mini and US$299 for the standard LimeSDR.
 
In this post we’ll give a brief unboxing and review of the LimeSDR Mini. If you’re interested take a look at our previous unboxing and initial review of the standard LimeSDR as well.

Unboxing

The LimeSDR Mini came in a small black box inside an anti-static bag. No accessories like antennas are included in the package. The PCB comes without any enclosure, but an enclosure can be ordered as an additional extra. The size of the PCB is similar to an RTL-SDR, but a little wider. The RF sensitive components are covered with a shielding can. Removing the can reveals the main Lime System RF chip, the LMS7002M, as well as several RF transformer matching circuits.
 
One end of the PCB has a standard USB-A connector, whilst the other end has two SMA ports, one for receiving and the other for transmitting.
limesdrmini_box2
limesdrmini_box3
limesdrmini_box4

 

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Video Comparison of the Airspy HF+ and SDRplay RSP1A on the FM Broadcast Band

Frequent reviewer of SDR products Mile Kokotov has just uploaded on his YouTube channel a new video where he compares the Airspy HF+ against the SDRplay RSP1A on FM broadcast reception.

At first Mile compares the two against strong broadcast stations, and then later compares them on weak DX stations surrounded in amongst other strong stations. With the strong stations a difference between the two radios is impossible to detect. But with the weaker stations that are surrounded by strong signals the Airspy HF+ has the edge with it's higher dynamic range and sensitivity.

Mile writes:

In this video I am comparing two popular SDR-Receivers (Airspy HF+ and SDRplay RSP1A) on FM Broadcast Band.

I have made few recordings with every receiver with the same antenna trying to set the best SNR = signal-to-noise ratio.

My intention was to ensure the same conditions for both SDR`s in order to make as fair as possible comparison.

No DSP enhancing on the SDR`s was used.

Antenna was Vertical Dipole.

When receiving signals are strong enough, You should not expect the difference between most receivers to be very obvious!

If you compare one average transceiver (which cost about $ 1000 USD) and top class transceiver which cost ten times more, the difference in receiving average signals will be very small too. Almost negligible! But when you have difficult conditions, the very weak signal between many strong signals, than the better receiver will receive the weak signal readable enough, but cheaper receiver will not. Today it is not a problem to design and produce the sensitive receiver, but it is far more difficult to design and produce high dynamic receiver for reasonable price! The Airspy HF+ and RSP1A are very very good SDR-receivers. They have different customers target and have strong and weak sides. For examle Airspy HF+ has better dynamics in frequency range where it is designed for, but RSP1A, on the other hand, has broadband coverage...

Airspy HF+ vs SDRplay RSP1A Comparison on FM Broadcast Band

A YouTube Review of the ColibriNANO SDR with Remote Server and Web Interface Demo

Over on YouTube user Laboenligne.ca has uploaded a review of the ColibriNANO. If you didn't already know the ColibriNANO is a low cost but high performance direct sampling receiver designed for the HF bands. Currently it costs $269.95 US from nsiradio. It now competes almost directly with the recently released Airspy HF+ which is a lower cost $199 unit with similar performance specifications.

Laboenligne.ca's review initially goes over the specs of the ColibriNANO and usage of the free ExpertSDR2 software that is used with the ColibriNANO. He also shows how the ColibriNANO can be connected to a Raspberry Pi 3 and used remotely over the internet. This is similar to the Airspy's SpyServer, but the difference is that ColibriNANO's server interface works in a browser via HTML5, so it can be used on any platform including mobile devices. Of course the ExpertSDR2 software can also be used to connect to the server as well. In his review Laboenligne.ca notes that he is very impressed with the remote web interface and has set up a public server demonstration of his ColibriNANO available at vpn.laboenligne.ca. He notes that if there is no reception to try again later, as he may be using the antenna on another radio.

The ColibriNANO SDR receiver review (English version)

Video Comparison of the Airspy HF+, SDRplay RSP1A and ColibriNANO on VLF to MF

Over on his YouTube Channel Mile Kokotov has uploaded a video that compares three mid priced SDRs: the Airspy HF+, the SDRplay RSP1A and the ColibriNANO. Each SDR is compared on several ALPHA and NBD morse code stations which exist in his tests from between 14 kHz to 474 kHz. He writes:

In this video I am comparing three SDR-Receivers. I have made few recordings with every receiver with the same antenna and choose the best one (one with the best SNR = signal-to-noise ratio). My intention was to ensure the same conditions for all three SDR`s in order to make as fair as possible comparison. For example, I was set the frequency span displayed on the window to be as same as possible for all three receivers. The vertical axis for the signal stregth, was set to be equal (in decibels) too.Airspy HF+ and ColibriNANO was set to their minimum sample rate (48 kHz). RSP1A was set to minimum sample rate (2 MHz and 8 decimation).

No DSP enhancing on the SDR`s was used except APF (Audio peak filter) on ColibriNANO (I forgot to swith off).

The differences between each receiver as very difficult to detect as only really challenging signal conditions will really set them apart. Mile also added in a comment:

You should not expect the difference to be very obvious! If you compare one average transceiver (which cost about $ 1000 USD) and top class transceiver which cost ten times more, the difference in the receiving the average signals will be very small too. Almost negligible! But when you have difficult conditions, the very weak signal between many strong signals, than the better receiver will receive the weak signal readable enough, but cheaper receiver will not. Today it is not a problem to design and produce the sensitive receiver, but it is very difficult to design and produce high dynamic receiver for reasonable price! The Airspy HF+ and RSP1A are very very good SDR-receivers. They have different customers target and have strong and weak sides. For example Airspy HF+ has better dynamics in frequency range where it is designed for, but RSP1A, on the other hand, has broadband coverage...

SDR Receivers Comparison on VLF, LW and NDB band

Several new SDRPlay RSP1A Reviews

Like the HF+ mentioned in the previous post, the RSP1A SDR was also recently released and has now had enough time in the wild to gather up a few online reviews. If you didn't already know, the $99 US SDRplay RSP1A is a revision of the RSP1. Compared to the RSP1 it significantly improves the filtering and front end design. We have our own review of the RSP1A unit here, and we mentioned some early reviews from other bloggers in this linked post. Below we post some of the new reviews that we are aware of which have come out since our last post.

Robert Nagy

In his video Robery Nagy does a full review of the RSP1A including a 15 minute primer on SDRs. This is great if you want a brief introduction to understanding how SDRs actually work, and what performance measures are important for comparing them. In the second half of the video Robert shows how to use SDRuno and shows the RSP1A in action.

SDRplay RSP 1A Review and SDR Primer

Mile Kokotov

In this video Mile Kokotov demonstrates the HF+ receiving a CW contest in his home country of Macedonia with the RSP1A and a full-size half wave resonant dipole antenna. He writes:

CQ World Wide DX Contest (CW) receiving in Macedonia with SDRplay RSP1A SDR-receiver and SDRuno software on 80m-Band with full-size half-wave (40 meters long) resonant dipole antenna.

Contest conditions are always big challenge to any receiver dynamics. Here you can see only 60 kHz wide frequency spectrum fulfilled with many competitor stations "fighting each other". In addition, there are local radio-station (only 1 km from my place) with huge signal...

RSP1A SDR receiver and SDRuno software - CQ World Wide DX Contest (CW) 2017

The Radio Hobbyist

In The Radio Hobbyist's video on YouTube Rick (VE3CNU) unboxes his RSP1A and shows the setup and download of SDRuno. He then goes are demonstrates reception on various signals.

Introducing the RSP1A SDR from SDRPlay

icholakov

In icholakov's video on YouTube he compares the older RSP1 with the newer RSP1A on medium wave and shortwave reception using a dipole in a noisy suburban RF setting. Differences are hard to detect as the signals he tests with are not likely to cause any overloading issues, but the RSP1A does seem to have a slightly less noise.

SDRPlay RSP1A vs, RSP1 comparison

Several new Airspy HF+ Reviews

The new Airspy HF+ SDR receiver has now been shipped to multiple customers and reviewers, and new reviews are coming online fast. If you weren't already aware, the Airspy HF+ was a hotly anticipated low cost, but high performance HF speciality SDR receiver. The claims are that it can compete with the high end $500 US+ units. We have our own review of an early model here. Below are some new reviews that we are aware of.

Nils DK8OK's photo of the Airspy HF+.
Nils DK8OK's photo of the Airspy HF+.

Nils Schiffhauer - DK8OK

On his blog Nils presents us with a comprehensive set of audio recordings comparing the $525 US Elad FDM-S2 with the $199 US Airspy HF+. He compares the two receivers on various shortwave broadcast stations, time stations, and an airport VOLMET. The recordings are identical, with the two radios recording the same signals simultaneously via a splitter.

Both receivers produce excellent results so you will probably need headphones and keen ears to be able to tell the difference.

Mile Kokotov

In this review YouTube video Mile Kokotov presents a comparison of the Airspy HF+ vs. the ColibriNANO, a similarly specced SDR dongle. He writes:

In this video I am comparing two high quality SDR Receivers: Airspy HF+ and ColibriNANO. They both have 16 bit Analog-to-Digital Converter. Comparison was made with the same overall conditions.

For example, both receivers was set with equal size spectrum windows, with the same amount of decibels in their scale, and the same high of the spectrum windows.
ColibriNANO has LNA gain slider which was set to maximum SNR.

Airspy HF+, on the other hand, has no LNA gain control.
The SV2HQL/Beacon was chosen as a test signal on 3579.32 kHz (on 80m band)

Antenna is half-wave resonant Dipole (40 meters long) for 80m band.

In the second part of the video I was inserted 27 dB external Attenuator on both receivers. ColibriNANO automatically increased the LNA gain and sets itself to maximum SNR. With this amount of attenuation, The Airspy HF+ noise floor level was at about the same place in spectrum window like ColibriNANO, Unlike in the first part of the video, when no external attenuator was used.

Both SDR-receivers are very good! Which is better? I leave on you to judge...

Airspy HF+ vs ColibriNANO Comparison on 3.579 MHz

Mile also does a second test with his HF+ and an active Mini-Whip antenna. He writes:

Airspy HF+ is superb High-Dynamic HF and VHF SDR-receiver and I am impressed with it. In order to minimize possible negative effect on signal path from antenna connector to tuner input, Airspy HF+ has no internal attenuator. Developers takes in account that this SDR-receiver has enough dynamic range that is very difficult to overload it. Actually it is true for most cases. But, if we want to use some type of active antenna (with internal amplification) like Mini-Whip Active Antenna for example, it is good idea to add an external attenuator between antenna and receiver HF-input connector, in order to have opportunity to lower the signal level from the active antenna, and to avoid possible overload issues. In this video I am presented some scenario (receiving MW AM band) when my homemade external step-attenuator is more than welcome! By the way, the external step-attenuator is very easy to made in almost no money. All you need is 9 resistors, three switches and one metal box) I have 5.5 dB switch, 10.5 dB switch and 22 dB switch. It can be set for 8 various combinations: 0, -5.5 dB, -10.5 dB, -16 dB, -22 dB, -27.5 dB, -32.5 dB and -38 dB.

You can see on this video that the AM Broadcast signal from Macedonian Radio on 810 kHz is very strong. The Antenna is about 30 km from my house. It is self standing huge 185 meters high vertical antenna, radiating enormous RF-power, so I have to use my homemade attenuator I mentioned it before.

Airspy HF+ SDR Receiver with Mini-Whip Active Antenna and External Attenuator

The SWLing Post Blog

Here Thomas of the SWLing post blog has posted a brief review of his HF+ unit. He notes how the HF+ is very compact, with a durable enclosure and how easy it was to set up with it being completely plug and play. So far Thomas hasn't fully evaluated the performance, but his first impressions are good.

Adam 9A4QV

In his two videos Adam doesn't directly review the Airspy HF+, but he does show some pretty impressive reception with his Skyloop antenna.

CQWW-2017 the end of the contest AirspyHF+

CQWW-2017 using AirSPY HF+ and 250 feet long skyloop antenna

RadioHobbyist (Update: 8 Dec 2017)

This review by RadioHobbyist just came online shortly after this post went out. It compares the HF+ against the expensive $1449 US NetSDR using sound samples from both radios. The difference between the two radios is almost undetectable.