Many thanks to SWLing Post contributor, TomL, who shares the following guest post:
Recording Music on Shortwave Part 2 – Weak signal recovery
The QRM noise cloud surrounding my condominium motivated my first foray into noise reduction software to find a little relief (Please refer to Part 1 posted here) using SDR recordings. I was able to use the freeware software Audacity to reduce some of that type of noise to tolerable levels on strong broadcasts. But what about non-condo noise, like out in the field??
I took my trusty Loop On Ground antenna to the usual county park Forest Preserve which is relatively low in RF noise. I did some usual recording on 25 meters and poked around for something being captured by SDR Console. On 11910 kHz is NHK broadcasting daily from Koga, Japan. It is hearable at this location but is always an S7 or weaker signal despite its 300 KW of power no doubt due to being beamed away from the Midwest USA.
I recorded it using the SDR Console 10kHz bandwidth filter and created a separate noise recording from a nearby empty frequency. Here is the 2 minute portion of a Japanese music teacher. No noise reduction was applied:
I opened the noise and broadcast recordings in Audacity to see what I could do. Part 1 of my previously mentioned post details how I apply the Noise file. A big downside of using any kind of noise reduction software is that it is ridiculously easy to destroy the desirable characteristics of the original recording. Applying too much noise reduction, especially in the presence of constant, spiky lightning noises, will create both digital artifacts as well as very dull sounding results. So I used the Effect – Noise Reduction (NR) feature very carefully.
In this example, I used the Effect – Amplify feature on the one minute noise file. I applied just +1dB of Amplify to the whole file. Then I highlighted a 10 second section I thought was representative of the general background noise and chose Edit – Copy. Then, I opened the broadcast file, Pasted the 10 seconds of noise to the END of the file and highlighted just the 10 seconds of noise. Then I chose Effect – Noise Reduction – Get Noise Profile button. Amplifying the noise file by +1db does not sound like much but it seems to help according to my tests. Anymore than this and the Noise Profile would not recognize the noise without destroying the music.
I used the NR feature three times in succession using the following (NoiseReduction/Sensitivity/FrequencySmoothing) settings: Pass1 (3dB/0.79/1), Pass2 (2dB/1.28/1), Pass3 (1dB/2.05/0). Part of what I listened for was choosing the Residue circle and Preview button for any music or dialog that was being filtered out. If I heard something that came from the desired part of the recording in Residue, I knew that I hit the limit concerning the combination of Noise reduction and Sensitivity settings to engage. I used those Residue & Preview buttons over and over again with different settings to make sure I wasn’t getting rid of anything wanted. I also used the higher Noise reduction with lower Sensitivity to try to get rid of any momentary spiky type noise that is often associated with SWLing.
I messed around with a lot of test outputs of differing dB and Sensitivities and a lot seemed to depend on the strength of the broadcast signal compared to the noise. If the broadcast was weak, I could push the dB and Sensitivities a little harder. I also noted that with strong signal broadcasts, I could NOT use more than 1 dB of Noise reduction beyond a Sensitivity of about 0.85 without causing damage to the musical fidelity. This was a pretty low level of nuanced manipulation. Because of these minor level Audacity software settings, it dawned on me that it is very helpful to already be using a low-noise antenna design.
If the Sensitivity numbers look familiar, that is because I tried basing the series of Sensitivity on Fibonacci numbers 0.618 and 0.786. Don’t ask me why these type of numbers, they just ended up sounding better to me. I also needed a structured approach compared to just using random numbers! Probably any other similarly spaced Sensitivity numbers would work just fine, too.
Now if you really want to go crazy with this, add Pseudo Stereo to your favorite version of this file (also detailed in Part 1) and playback the file using VLC Media Player. That software has a couple of interesting features such as an Equalizer and a Stereo Widener. You may or may not like using these features but sometimes it helps with intelligibility of the voice and/or music [VLC will also let you right-click a folder of music and choose to play all it finds there without having to import each MP3 file into a special “Library” of music tracks where they bombard you with advertisements].
You can also turn on Windows Sonic for Headphones if you are using the Windows operating system. However, this can sometimes be too much audio manipulation for my tastes!
Here is the resulting NHK noise-reduced file with 9ms of delay with High & Low Filters:
Five days later I was out in the field again. This time I found Radio Thailand on 11920 kHz finishing up a Thai broadcast. It was a weaker S5 signal than the NHK example, so it would be a good test.
When I got home, I recorded the broadcast file at a Bandwidth filter of 8 kHz and using Slow AGC and the extra Noise file at 12kHz using Fast AGC. In a previous test I had noticed a very slight improvement in sound quality in the way noise seems to get out of the way quicker compared to Slow AGC (which is usually how I listen to shortwave broadcasters). I now try to remember to record the Noise file with Fast AGC.
Here is the original without any noise reduction:
This time the Noise file using Amplify +1dB did not help and I used it as-is for the 10 second Noise Profile. I then tried multiple passes of NR at higher and higher Sensitivities and ended up with these settings the best: Pass1 (1dB/0.79/0), Pass2 (1dB/1.27/0), Pass3 (1dB/2.05/0), Pass4 (1dB/3.33/0).
As a comparison, I tried recording only with SDR Console’s noise reduction NR1 set to 3dB and got this. I hear more noise and less of the music coming through:
Now for more crazy Pseudo Stereo to finish up the Audacity 4Pass version (nice Interval Signal of Buddhist bells ringing and station ID at the very end):
I do not understand why applying 3 or 4 separate 1dB Sensitivities of noise reduction is superior to just one Pass at 3dB Sensitivity (in Audacity) or the one 3dB noise reduction (in SDR Console). My guess is that doing 1 dB at different Sensitivities shaves off some spiky noise a little at a time, somehow allowing for more of the musical notes to poke through the noise cloud. Who knows but I can hear a difference in subtle musical notes and sharpness of voice and instruments. Probably the Fast AGC helps too.
Music is a Universal Language that we can share even when we don’t understand a word they are saying. And there is more music on the air than I thought. Some of these recordings sound surprisingly pleasing after noise reduction. The fake stereo is pumped through a CCrane FM Transmitter to a few radios in the home, or I can use the Beyerdynamic DT990 Pro headphones.
Many thanks to SWLing Post contributor, TomL, who shares the following guest post:
Recording Music on Shortwave
I recently became curious about the seasonal music updates posted by Alan Roe. It is a nicely detailed list of musical offerings to be heard. Kudos to Alan who has spent the time and effort to make it much easier to see at a glance what might be on the airwaves in an easy to read tabular format. I do not know of any other listing specifically for shortwave music in any publication or web site. I especially like the way it lists everything in UTC time since I might want to look for certain time slots to record. For some listings, I would need to go outdoors away from noise to listen to certain broadcasts. Current web page is here: https://swling.com/blog/resources/alan-roes-guide-to-music-on-shortwave/ .
As a side note, I have also found a lot of music embedded in the middle of broadcasts that are unannounced, unattributed, and not part of a regular feature program. That can be a treasure trove of local music you might not be able to find anywhere on the internet. It can be worth recording a spectrum of frequencies using the capabilities of the SDR and then quickly combing through the broadcasts at two-minute intervals (most songs are three minutes or longer). In maybe ten minutes, I will have at least identified all of the listenable music that may or may not be worth saving to a separate file.
Whether at home or outdoors, I have wanted to try to record shortwave broadcasts of music using my AirSpy HF+ but never getting around to it until now. There is a certain learning curve to dealing with music compared to just a news summary or editorial. I found myself wishing I could improve the fidelity of what I was hearing. From static crashes, bad power line noise, fading signals, and adjacent channel interference, it can be quite difficult to get the full appreciation from the musical impact.
I am starting to monitor the stronger shortwave stations like WRMI, Radio Romania International, Radio Nacional do Amazonia, etc. These type of stations can be received in a strong enough manner to get good quality recordings (at least according to shortwave listening experience). I am also finding that I appreciate much more than before the effort that these broadcasters put into creating content/commentary to go along with the music and little pieces of background info about the music or the artist. I have also noticed how exact some broadcasters are in timing the music into the limited time slots. For instance, Radio Romania International tries to offer one Contemporary piece of music exactly at 14 minutes, Traditional music exactly at 30 minutes, and a Folk tune exactly at 52 minutes into the program (whether in English, French, or Spanish), with nice fade-outs if the music goes too long.
One thing I ran into was to bother checking my hearing range. If someone has impaired hearing, it does not make much sense to create files that have a lot of sound out of one’s hearing range. I found this YouTube video (among a bunch of others) and listened to the frequency sweep using my Beyerdynamic DT-990 Pro headphones (audiophile/studio type headphones). My hearing is approximately from 29 Hz through 14400 Hz. Of course, the extremes fall off drastically, and as with most people, my hearing is most sensitive in the 2000 through 6000 Hz range.
Let’s assume that you already know how to record IQ files using your SDR software and can play them back (In the example below, I recorded the whole 49 meter band outputting a series of 1GB WAV files). Then, when playing back to record to individual files, I have to choose the filters and noise reduction I want. This gets subjective. If I do not want to keep huge numbers of Terabytes of WAV files over time, I will want to record to individual WAV files and then delete the much larger spectrum recording. You might tell me to just record to MP3 or WMA files because there is that option in the SDR software. We will get into that as we go along. For the time being, I do not want to keep buying Terabytes of hard drives to hold onto the original spectrum recordings.
After lots of trial and error, I came up with this workflow:
Record the meter band spectrum of interest using the SDR software.
Record individual snippets of each broadcast in that spectrum to new individual WAV files. This includes not lopping-off any announcer notes about the music I want to retain. I also have to choose the bandwidth filter and any noise reduction options in the software. Because I am not keeping Terabytes of info, this is a permanent decision.
Take an individual recording and apply more processing to it.
Convert the processed recording to any number of final output formats for further consumption and/or sharing.
Repeat steps 3 & 4 to take care of all the individual WAV files.
Step 4 allows me to create whatever file format I might need it to be: WAV, MP3, WMA, or even use it as background sound to a video if I so choose. There are also different ways to create some of these files with different quality settings depending on what is needed. I have chosen to listen to the individual WAV files for personal consumption but there may come a time to create high quality MP3 files and transfer those to a portable player I can take anywhere (or share with anyone).
The example below is a snippet from the latest Radio Northern Europe International broadcast on WRMI. WRMI has some decent equipment and I like how clean and wide is the bandwidth of many of the music programs. This is captured on the AirSpy HF+ using SDR Console V.3 with a user-defined 12kHz filter (11kHz also seemed somewhat similar sounding).
If you click on the ellipses, you can Copy an existing filter, type in a new title and change the bandwidth. I also played around with the different Windowing types and found that I like the Blackman-Harris (7) type best for music and the Hann type for smooth speech rendering (the Kaiser-Bessel types can also have more “punch” for voice recordings). Click OK TWICE to save the changes.
I also use Slow AGC and the SAM (Sync with both sidebands) to reduce the chance of distortion as the signal fades. I found that trying to use only one sideband while in Sync mode would make the reception open to loss of Sync with the musical notes warbling and varying all over the place!
The SDR Console software has a number of noise reduction choices. I tried NR1 through 4 and found the smoothest response to music to be NR1 with no more than 3 dB reduction. More than this seemed to muffle the musical notes, especially acoustic instruments and higher pitched voices. Part of the problem has to do with trying to preserve the crispness of the articulation of the sound and combating shortwave noise at the same time. At this time, I have chosen NOT to use any NR mode. More about noise reduction below.
Generic MP3 sounds really bland to my ears, so creating higher quality files will be important to me. I have been using Audacity which can apply processing and special effects to WAV files and export to any number of file formats. WAV files are a wonderful thing. It is a “lossless” file format which means that every single “bit” of computer input is captured and preserved in the file depending on the resolution of the recording device. This allows one to create any number of those “lossy” output formats or even another WAV file with special effects added. You can get it here:
One special effect is listed as “Noise Reduction”. I literally stumbled upon it while reading something else about Audacity (manual link). Here is how I use it for a shortwave broadcast. Open the original spectrum recording (in this example the 49m band). Tune about 25kHz away from the broadcast that was just recorded. Remember, my hearing extends at least to 14.4k plus there is still the pesky issue of sideband splatter of bandwidth filters. The old time ceramic and mechanical filters use to spec something called “skirt selectivity” -60db or more down from the center frequency. This is still an issue with DSP filters even though they SAY they are measured down to -140dB; I can still hear a raspy sideband splatter from strong stations!
Find the same time frame that you recorded the broadcast and make sure it is the same bandwidth filter, AGC, and any noise reduction used. Now record one minute of empty noise to a WAV file. Fortunately on 5850 kHz, WRMI has no adjacent interference.
Now in Audacity, open the noise sample and listen for a 5 to 10 second space to copy that is relatively uniform in noise. We don’t want much beyond that and we don’t really want noise spikes. The object is to reduce background noise. In this case, I chose Start 39 seconds and End 44 seconds. Choose Edit – Copy (or CTRL-C).
Choose File Open and find the broadcast WAV file in question. Now click on the end-of-file arrow or manually type in the Audio Position (in this example 1 minute 15 seconds). Now Paste (or CTRL-V) the 5 seconds of noise to the end of the broadcast file. Now, while the pasted noise is still highlighted, go immediately to Effect – Noise Reduction and choose the button Get Noise Profile. It will blink quickly to read the highlighted 5 seconds of noise and disappear.
Now select all with CTRL-A and the whole file is selected. Go immediately to Effect – Noise Reduction and choose the parameters in “Step 2”. Through some trial and error, I found 3db reduction has a noticeable effect without compromising the music. I have used up to 5 db for some music recorded with narrower bandwidths. Higher levels of noise reduction seemed to create an artificial flatness that was disturbing to me. I also use a Sensitivity of 0.50 and Frequency smoothing of 0. You can choose the Preview button while the Residue circle is checked to actually hear the noise being eliminated. Press OK in order to process the noise reduction. You should now see the waveform change slightly as the noise is filtered. In a nutshell, I find this to be a better noise reduction than using 3db of NR1 in the SDR Console software. Don’t forget to snip off those 5 seconds of noise before saving the file.
The SDR Console software has an Option for Pseudo Stereo (for playback only) and it can be useful for Amateur Radio receiving, especially in noisy band conditions when one is straining to hear the other person’s call sign and location. There is a way in Audacity to add a fake kind of stereo effect to mono audio files. I found a useful YouTube video that explained it very clearly.
I do everything listed there except for the Reverb effect. I find that too fake for my tastes.
I found the added 10ms of Delay on the right channel to be a little too much, so I use 9ms.
My High Pass filter settings are 80 Hz and 24dB/octave. This is based partly on my hearing preferences as well as established industry standards. There was a lot of science and audio engineering that went into creating the THX home theater crossover standard. There is also science that says that anything below 200 Hz is omnidirectional. The suggested 48dB/octave is too steep in my opinion.
My Low Pass filter settings are more squishy. The YouTube video suggests 8000 Hz and 6dB/octave. I feel that is too gentle a rolloff into the upper midrange. I use 9000 Hz at 12dB/octave for very strong, high quality shortwave broadcasters like WRMI. For more constrained quality broadcasts, like due to limited bandwidth (Cuban broadcasters) or adjacent channel interference, I will decrease down to 8000 or 7000 Hz but still use a 12dB/octave rolloff. This is subjective but it also means I am making a conscious decision to add that processing to the recording for future listening.
Typical MP3 files are a Constant Bit Rate of 128k. Some interviews and voice-only podcasts are only 64k. This is adequate but for recording detail in the music I prefer higher quality settings. Frankly, with these days of 4G cell phone service and Unlimited Data minutes on cell phone plans, there is NO good reason to limit MP3 files to just adequate quality levels. The typical MP3 file sounds limited in frequency range (muffled sounding) to me and very lacking in dynamic range (narrow amplitude). This would include limits on stereo files which are about twice the file size of mono files.
I have tried creating WMA files and I actually like the quality a little better than high quality MP3 files. The WMA files seem slightly more “airy” and defined to my ears. But it is a proprietary format from Microsoft and not all web sites or devices will easily play them. They are also a fixed standard and one cannot easily change the quality settings if forced to use a lower quality rendering.
There are many web sites talking about MP3 files, but I found this blog post helpful in summarizing in one paragraph the higher quality settings for a nice MP3 recording using VBR-ABR mode.
So finally for my examples. Since most web sites still prefer MP3 files, I have created these using that blog post’s suggestions. Typically this is Min bitrate=32, Max bitrate=224, VBR quality=9, and Quality=High (Q=2). Let’s see if you can hear the differences. It would be much easier to hear if we were listening to WAV files, but those are way too big to post on this web site! The software I used is Xmedia Recode and I find it easy to use.
Many thanks to SWLing Post contributor, Mark (AE2EA) with the AWA, who writes:
Your loyal followers might be interested in this video of airchecks
recorded on aluminum discs in England of US broadcast stations in late
1933, from the Antique Wireless Museum.
From the AWA description:
These audio clips were recorded on aluminum discs using more of an embossing than cutting action. Reading an AWA Facebook post that the AWA doesn’t have the equipment or experience to digitize the very fragile audio information on these discs, email@example.com volunteered to do so. He did a great job is highly recommended for your consideration as a service for archival digitization and restoration.
The discs were in Peter R. Testan’s collection because they included recordings of station WBBC in Brooklyn, NY that his dad, Peter J, started. As well as being a broadcast owner and engineer, Peter J. Testan was also a ham operator. Pictures of his ham shack were featured in a recent issue of the AWA Journal.
While the calls are identifiable, the other programming in these recordings is difficult to listen to. The Creative Director of a New York City radio station remarked after listening: “”It’s so funny because I have DXers sending me EXACTLY the same quality audio as on these discs. Nothing has changed in nearly 100 years!!!”
The audio quality in this video has been enhanced from the original aluminum disc recordings through the use of bandpass filtering, noise reduction and compression, with the goal of removing some of the artifacts of the recording process.
It sometimes seems that one of the biggest enemies of a radio enthusiast these days is RFI (radio frequency interference), which is to say, human-originated noise that infiltrates––and plagues––vast chunks of our radio spectrum.
Yet I believe RFI has, in a sense, also managed to energize––and even mobilize––many radio enthusiasts. How? By drawing them out of their houses and shacks into the field––to a local park, lake, river, mountain, woodland, or beach––away from switching power supplies, light dimmers, street lights, and other RFI-spewing devices.
Shortwave and mediumwave broadcast listeners have it easy, comparatively speaking. They can simply grab a favorite portable receiver, perhaps an external antenna, then hit the field to enjoy the benefits of a low-noise environment. In that a portable receiver is something of a self-contained listening post, it’s incredibly easy to transport it anywhere you like.
Ham radio operators, on the other hand, need to pack more for field operations. At a minimum, they need a transceiver, an antenna, a power source, not to mention, a mic, key, and/or computing device for digital modes. Thankfully, technology has begun miniaturizing ham radio transceivers, making them more efficient in the use of battery power, and integrating a number of accessories within one unit.
Photo from the 2019 Tokyo Ham Fair
Case in point: in 2019 at Tokyo’s Ham Fair, Icom announced their first QRP (low-power) radio in the better part of two decades: the Icom IC-705.
Introducing the Icom IC-705
It was love at first sight among fans of Icom when the 2019 announcement was made. Why? The instant thrill came courtesy of the IC-705’s resemblance––in miniature––to the IC-7300, one of Icom’s most popular transceivers of all time. Not only that, but the IC-705 sported even more features and a broader frequency range than the IC-7300. What wasn’t to love?
But of course, unlike the IC-7300, which can output 100 watts, the IC-705’s maximum output is just 10 watts with an external 12V power source, or 5 watts with the supplied Icom BP-272 Li-ion battery pack. Nevertheless, enthusiasts who love field radio––this article’s writer being among them––were very pleased to see Icom design a flagship QRP radio that could take some portable operators to the next level. Power was traded for portability, and for field operators, this was a reasonable trade.
And since, again, the IC-705 has even more features, modes, and frequency range than the venerable IC-7300, I felt it important to note them up front. Here are a few of its most notable features, many of which are not available on its bulkier predecessor:
VHF and UHF multimode operation
Built-in Wifi connectivity
Built-in Bluetooth connectivity
The receiver design is similar to the IC-7300 below 25 MHz in that it provides a direct conversion. Above 25 MHz, however, it operates as a superheterodyne receiver. While the user would never know this in operation, it’s a clever way for Icom to keep costs down on such a wideband radio.
At time of publishing, there are no other portable transceivers that sport all of the features of the Icom IC-705. It has, in a sense, carved out its very own market niche…At least for now.
I’ve owned the IC-705 since late September 2020, and I still haven’t fully explored this radio’s remarkable capabilities. It’s really a marvel of ham radio technology, and I’m having fun exploring what it can do.
One conspicuous omission
Let’s go ahead and address this promptly. The IC-705 does have one glaring shortcoming. It lacks one feature that is standard on the larger 100-watt IC-7300: an internal antenna tuner (ATU).
To be frank, I was a little surprised that the IC-705 didn’t include an internal ATU, since it otherwise sports so many, many features. Not having an internal ATU, like a number of other general coverage QRP transceivers in its class, definitely feels like a missed opportunity. With an ATU, the ‘705 would truly be in a class of its own.
I’m sure Icom either left the internal ATU out of the plan due to space limitations––perhaps wanting to keep the unit as compact as possible?––or possibly to keep the price down? I’m not sure. At release, the price was $1300 US, which is undoubtedly on the higher side of this market segment; at that price point, it might as well have included an ATU.
With that said, not having an internal ATU is still not a disqualifier for me. Why? Because I have a number of resonant antennas I can add on when in the field, a remote ATU at home, and a couple of portable external ATUs, as well. Yes, it would be helpful to have it built in––as on my Elecraft KX1, KX2, and KX3, or on the ($425) Xiegu G90––but for me it’s not a deal-breaker.
One other minor omission? A simple tilt stand or foot. I do wish Icom had included some sort of foot on the bottom of the IC-705 so that it could be propped up for a better angle of operation. Without a tilt stand or foot, the IC-705 rests flat on a surface, making its screen a bit awkward to view. Of course, a number of third-party tilt stands are available on the market. And if you have a 3D printer or access to one, you can find a wide variety of options to simply print at home. I printed this super simple tilt foot, which works brilliantly.
But why not include one, Icom?
My 3D printed tilt foot
But while the IC-705 lacks a tilt foot, it actually sports a number of connection points on the bottom, including a standard tripod mount. Thank you, Icom, for at least including that (other radio manufactures please take note)!
Funny: the IC-705 is the first new transceiver I’ve purchased with a color box.
If you’ve ever owned or operated the Icom IC-7300, you already know how to operate many of the functions on the IC-705. The user interfaces on the touch screens are identical. Features that are unique to the IC-705 are easy to find and follow the same standard Icom user-interface workflow.
Having less front faceplate real estate, the IC-705 has less buttons than the IC-7300––about 11 less than its big brother, to be exact. However, the twin passband, gain, multi-function knob and encoder are in the same positions and layout as on the IC-7300.
And if you’ve never used an IC-7300 before, no worries: this is one of the more user-friendly interfaces you’ll find on a ham radio transceiver.
The build of the IC-705 is excellent. It’s not exactly hardened for the elements––there is no waterproof rating or dust rating, for example––but it gives the impression of a solid little radio, likely to withstand a bit of less-than-delicate handling. Yet even though it’s designed to be a portable field radio, I’ll admit that the front panel and especially the color touchscreen feel a little vulnerable. I do worry about damaging that touchscreen while the radio travels in my backpack.
The Icom LC-192
On the topic of backpacks, Icom released a custom backpack (the LC-192) specifically for the IC-705, Icom AH-705 ATU, antennas, and accessories. I did not consider purchasing this backpack, although I’m sure some operators would appreciate it, as it has dedicated compartments for supplies and the radio can be attached to the floor of the backpack’s top compartment. Again, I passed because I’m a bit of a pack fanatic and tend to grab gear that’s more tactical and weatherproof.
IC-705 and Elecraft T1 ATU at Toxaway Game Land
While its in my Red Oxx or GoRuck backpack, I house the IC-705 in a $14 Ape Case Camera insert. Eventually I want to find a better solution, but this does help pad the IC-705 while in my backpack and certainly fits it like a glove––hopefully protecting that touchscreen.
A number of third-party manufacturers have designed protective “cages” and side panels for the IC-705, but I’ve been a bit reluctant to purchase one because I feel they may add too much weight and bulk to the radio.
To the field!
Sandy Mush State Game Land
The day after I received my Icom IC-705, I took it to the field to activate Sandy Mush State Game Land for the Parks On The Air (POTA) program. Typically, when I review a new radio, I spend a few hours with it in the shack before taking it to the field. In this case, however, I felt comfortable enough with the IC-705 user interface, so I decided to skip that step entirely––I was eager to see if this little radio would live up to expectations.
The previous evening, I’d connected the IC-705 to my 13.8V power supply, so the BP-272 battery pack was fully-charged and attached to the IC-705. There was no need for an external battery to be connected.
Getting on the air that day was very straightforward; indeed, the set-up couldn’t have been more simple: radio plus antenna. I connected the IC-705 to a Vibroplex EFT-MTR end-fed 40, 30, and 20-meter resonant antenna, thus an external antenna tuner was not required.
The Vibroplex/End-Fedz EFT-MTR antenna
Next, I plugged in the included speaker/mic, spotted myself to the POTA network, and started working stations. I asked for audio reports and all were very positive using only the default audio settings. Obviously, the small hand mic works quite well. I did quickly decide to unplug one of the two connectors of the speaker mic (the speaker audio side) so that the received audio wouldn’t be pumped through the hand mic, using the much better IC-705 front-facing speaker.
In the field that day, I had a few objectives in mind:
See how well the supplied hand mic works for SSB contacts, thus intended to ask for audio reports
Check out full break-in QSK operation in CW mode
Measure exactly how long a fully-charged Icom BP-272 Li-ion battery pack would power the IC-705 under intense operation
SSB at Lake Norman State Park
I was very quickly able to sort out how to record and use the voice memory keying features of the IC-705. There are a total of eight memory positions that can be recorded to the internal microSD card. It’s very simple to use one of the memories in “beacon” mode––simply press and hold one of the memory buttons and the recording is transmitted repeatedly until the user presses the PTT to disengage it. This is incredibly helpful when calling CQ; I typically set mine to play “CQ POTA, CQ POTA, this is K4SWL calling CQ for Parks On The Air.” I’ve also set a five-second gap between playback, allowing for return calls. As I’ve mentioned before, voice-memory keying is incredibly useful and saves one’s voice when calling CQ in the field.
The voice and CW-memory keying features of the IC-705 are robust enough that they could be used in a contest setting to automate workflow. One important note: voice-memory keying saves recordings to the internal MicroSD card. If that card is removed, formatted/erased, or if the file structure is altered, the voice-memory keyer will not recall recordings.
CW at South Mountains State Park
Next, I plugged in my paddles and started calling “CQ POTA” in CW.
As with the voice-memory keyer, CW-memory keying was incredibly easy to set up. Once again, the user once has eight memory positions. As the keyer plays a pre-recording sequence, the IC-705 will display the text being sent.
One of the questions I’m asked most by CW operators about the IC-705 is whether the radio has audible relay clicks during transmit/receive switching. Radios with loud relay clicks can be distracting. My preference these days is to operate in full break-in QSK mode, meaning, there is a transmit/receive change each time I form a character––it allows me space to hear someone break in, but results in much more clicking.
The IC-705 does have relay clicks, but these are very light––equal in volume to those of other Icom transceivers, neither louder nor softer. These clicks, fortunately, are not too distracting to me, and to be fair, I find I don’t even notice them as I operate. With that said, transceivers like my Elecraft KX2 and Mission RGO One use PIN diode switching, which is completely quiet.
Tapping the battery icon will open a larger battery capacity monitor.
My third objective at the first field outing was to test how long the Icom BP-272 Li-ion battery pack would power the IC-705 while calling CQ and working stations in both SSB and CW for an entire activation.
After nearly two hours of constant operation, the BP-272 still had nearly 40% of its capacity.
I didn’t expect this. I assumed it might power the IC-705 for perhaps 90 minutes, max. Fortunately, it seems at 5 watts, one BP-272 could carry you through more than one POTA or SOTA (Summits On The Air) activation. I was pleasantly surprised.
Four months later…
POTA activation at Tuttle Educational State Forest
Since that initial field test, I’ve taken the IC-705 on easily thirty or more individual POTA activations. I’ve also used it at home to chase POTA stations and rag chew with friends.
In short, I’ve found that the IC-705 is a brilliant, robust portable transceiver for SSB and/or CW and a pleasure to operate.
Herein lies the advantage of purchasing a radio from a legacy amateur radio manufacturer: it’s well-vetted right out the door, has no firmware quirks, and is built on iterations of popular radios before it.
I’ve found that IC-705 performance is solid: the receiver has a low noise floor, the audio is well-balanced, the AGC is stable at any setting, and it’s an incredibly sensitive and selective radio.
POTA activation at Lake Jame State Park
One huge advantage of the IC-705 is that it, like the IC-7300, has a built-in sound card for digital modes. This eliminates the need for an external sound card interface. After you’ve read the installation guide, and installed Icom’s USB drivers, simply plug the IC-705 into your computing device via USB cable and you can directly control the ‘705 with popular applications like WSJT-X.
I have not used the IC-705 for digital modes while in the field, but I have done so in the home shack. It was one of the easiest radios I’ve ever set up for FT8 and FT4.
I’m not the biggest digital mode operator, but if you are into it, I expect you’ll be very pleased with the IC-705. It must be one of the most portable, uncomplicated transceivers for digital mode operation currently on the market. I know a number of POTA activators have been using the IC-705 for FT8 and FT4.
Being perfectly honest here, I have a chequered history with the D-Star digital voice mode. I purchased an Icom ID-51a and D-Star hotspot several years ago because a local ham pretty much convinced me it was the coolest thing since sliced bread.
And in truth? It is rather amazing.
But at the end of the day I had to admit to myself that I’m an HF guy, and found the user interface and operating procedures just a bit too other-worldly. I kept the ID-51a for perhaps a year, then sold it, along with the hotspot.
Although I knew the IC-705 had D-Star built in, I really hadn’t given it a second thought. But since I’m a reviewer, I simply had to check it out. I still had my D-Star credentials from some years ago, so I set up the IC-705 and connected the transceiver to the Diamond dual band antenna on top of my house.
Fortunately, I was able to hit our only local D-Star repeater and connect on the first go. Note that, like the ID-51a, the IC-705 can use your GPS coordinates, then automatically find the closest D-Star repeater and load the frequency and settings from the default database on the IC-705 MicroSD card.
After reviewing a YouTube video demonstration, I was on the air with D-Star and found the user interface much easier to use than that of the ID-51a. It really helps having a large touch screen.
I’ll admit it: I’m warming back up to D-Star, and I have the IC-705 to thank for that.
Some day, I plan to use D-Star on HF, as well. I acknowledge that it might take some pre-arranging, but perhaps I could even make a D-Star POTA––or better yet, SOTA––contact, if the stars align. It’s certainly worth the experiment.
Let’s talk about broadcast listening
Radio Exterior de España’s interval signal on the IC-705’s waterfall display
Although I’m a pretty active ham radio operator, I’m an SWL and broadcast listener at heart. One of the appealing things about the IC-705 is its excellent receiver range (0.030-470.000 MHz) and multiple operating modes, as well as its adjustable bandwidth. Broadcast listeners will be happy to know that the AM bandwidth on the IC-705 can be widened to an impressive 10 kHz, which is certainly a stand-out among general coverage transceivers.
After turning on the IC-705 for the very first time, I tuned to the 31-meter band and cruised the dial. I felt like I was using a tabletop receiver: for such a small transceiver, the encoder is on the large side, and the controls are ergonomically designed. The spectrum display and waterfall are amazingly useful.
The front-facing speaker on the IC-705 is well-designed for audio clarity on the ham radio bands. It’s not a high-fidelity speaker, but it’s adequate and has enough “punch” to perform well in the field. Speakers on portable QRP radios are typically an afterthought and are terribly compromised due to space constraints within the chassis. The IC-705’s speaker design feels more deliberate, akin to what you might find on a mobile VHF/UHF rig. Broadcast listeners, in other words, will certainly want to hook the IC-705 up to an external speaker––or, better yet, use headphones––for weak-signal work.
While the received audio isn’t on par with a receiver like the Drake R8B, it’s pretty darn good for a portable general coverage transceiver. The audio is what I would call “flat,” but you are able to adjust the received audio in EQ settings to adjust them to your taste. Audio is well-tailored for the human voice, so I’ve found weak signal IDs are actually easy to grab on the air.
One of the brilliant things about the IC-705 is the fact that it has a built-in digital recorder. Both transmitted and received audio can be recorded in real time and saved to a removable MicroSD card. I made audio recordings of two broadcast stations on the 31-meter band as samples: the Voice of Greece (9420 kHz) and RadioExterior de España (9690 kHz). The Voice of Greece was moderately strong when I made the recording and Radio Exterior was quite strong. Click on the links to download the .mp3 files for each recording:
Voice of Greece
Radio Exterior de España
I’ve also used the built-in digital recorder to record long sessions of my favorite shortwave, AM, and FM stations. Even with the recorder on, I can typically achieve hours of listening on one battery charge and need no other power supply.
In short? The IC-705 makes for an excellent portable shortwave, mediumwave, and FM broadcast band-recording receiver.
The supplied BP-272 battery pack snaps snugly on the back of the IC-705
Power supply is always a concern when taking a transceiver on travels. Most transceivers need a 12-13.8 volt external supply, or an external battery, one that will eventually need to be charged.
This is not the case with the IC-705, because while it can be charged or powered via a 12-13.8V source, it can also be charged via a common 5V USB power supply. Simply insert any USB phone-charging cable into the MicroUSB port on the side of the IC-705, and it will charge the fully-depleted attached BP-272 battery pack in just over four hours.
Indeed, I traveled to visit family one week, and had plotted two park activations both en route and on the way back home. After my first activation, I quickly realized I forgot the supplied IC-705 power cord that I’d normally use to hook the IC-705 up to one of my LiFePo batteries. I was quite disappointed, expecting that I’d missed this opportunity. Then I remembered USB charging: I simply plugged the IC-705 up to my father’s phone charger, and in four hours, the battery was completely recharged.
To my knowledge, there are no other transceivers that have this capability without modification. A major plus for those of us who love to travel lightly!
POTA activation at the Zebulon Vance Historic Birthplace
Every radio has its pros and cons. When I begin a review of a radio, I take notes from the very beginning so that I don’t forget my initial impressions. Here’s the list I formed over the time I’ve spent evaluating the Icom IC-705.
TX: 160 – 6 meters, 2M, 70cm
RX: 0.030-470.000 MHz
Modes include SSB, CW, AM, FM, DV, RTTY
4.3 inch color touchscreen that’s (surprisingly) readable in full sunlight
Multiple means to power/charge:
Icom BP-272 battery pack (supplied) for 5 watts output
Can be charged via 12V power supply or
5V USB phone charger with standard MicroUSB plug (admittedly, I wish they would have adopted now standard USB-C rather than MicroUSB)
Angled speaker/mic connectors can be challenging to insert as they are too close to the recessed area behind front face, especially for those with larger fingers and/or if in chilly conditions in the field
MicroSD card also difficult to access––I use needle-nose pliers to remove and insert
POTA activation of Second Creek Game Land
I purchased the Icom IC-705 with the idea that I would review it and then sell it shortly thereafter. Much to the dismay of my (rather limited) radio funds, I find that I now want to keep the IC-705…indefinitely.
I didn’t think the IC-705 would fit into my QRP field radio “arsenal” very well because I tend to gravitate toward more compact radios that I can easily operate on a clipboard on my lap when necessary. My Elecraft KX2 (TSM November 2016), Elecraft KX1, LnR Precision LD-11 (TSM October 2016), and Mountain Topper MTR-3B probably best represent my field radio interests.
But I’m loving the versatility and overall performance of the IC-705. It’s providing an opportunity to do much more than most of my QRP radios allow.
Here are just a few of the things I’ve done with the IC-705 thus far:
Activated numerous parks in SSB and CW
Connected to a local D-Star repeater and talked with a fellow ‘705 owner in the UK
Listened to ATC traffic (and recorded it)
Listened to NOAA weather radio
Listened to and recorded local FM stations
Enjoyed proper FM DXing
Recorded GPS coordinates during a POTA/WWFF activation
Made numerous digital mode contacts by connecting the IC-705 directly to my Windows tablet
Made a 2-meter SSB contact
POTA activation of the Blue Ridge Parkway
Indeed, there are more features on this transceiver than I can fully cover in one review; truly, I consider that a very good thing.
So if you’re looking for a portable transceiver that can truly take you on a deep dive into the world of QRP HF, VHF, UHF, and even satisfy the SWL in you, look no further than the Icom IC-705.
Well played, Icom.
More Icom IC-705 articles, information, and resources:
Many thanks to SWLing Post contributor, TomL, who shares the following guest post:
Magnet Wire Vertical Loop Antenna
For those of you in a noisy condo like me, the environment does not give me many options. I was experimenting with a YouLoop on the wooden porch with somewhat acceptable results. For its size, it is an excellent performer, especially on the lower bands. Here is a very interesting review of the YouLoop, including close-up pictures of the innards of the phase inverter and 1:1 balun, by John S. Huggins. However, it is not waterproof and I was concerned about the ice and snow ruining it. I could tape up the connectors with waterproof tape but I also wanted something with a bigger capture area. A magnet wire stealth antenna might be just the thing!
I just happened to have a waterproof 1:1 ATU balun from Balun Designs that I was going to use for future Amateur Radio use whenever I get around to passing the next level test; it is total overkill for what I intended to use it for. It would make a good connection point and (this one) also acts as an RF choke as well. One can make a 1:1 balun by buying the right Type of ferrite core and winding it yourself. Here is just one idea from Palomar Engineers.
So I dusted it off, went to a local store to get a 100 foot spool of 26 gauge magnet wire and tested it strung up around my living room. It came out to be a rectangle about 42 feet in circumference. Results were usable. I expected lots of noise and there is a great deal across the bands, so only the strongest shortwave stations were received. However, I was surprised by how strong the mediumwave band was and good to listen to without an amplifier.
I am ambivalent towards trying to perfectly match the impedance since this is a broadband receive-only antenna and the impedance will vary greatly over MW and SW bands. And I don’t want to mess with a remotely controlled tuned loop since this antenna was destined for the outdoor porch. I tried a Cross Country Wireless preselector at my desk but had some mixed results. I later found out, by disconnecting things in series, that the preselector inline raised the noise level about 5 dBm, so I took it out for now. Perhaps it needs more internal shielding or the connecting cable is bad.
Polarization is an issue, too. I have read that most man-made noise (QRM) is vertically polarized, so why would I use a vertically oriented loop? Then I saw David Casler’s video on loop antennas where he explains that connecting a vertical loop antenna at the bottom or the top makes it horizontally polarized (connecting the coax on the side makes it vertically polarized). I never knew that! Horizontal polarization will mitigate some of the offending QRM as well as match the polarization of mediumwave band transmitters. Furthermore, I read that a horizontal loop will have poor signal pickup at low frequencies because it is not high enough off the ground, similar to a horizontal dipole. For now, a vertical loop connected to facilitate horizontal polarization is what I want.
A note about wire size. People make a big deal about it but those are mostly amateur radio people. Transmission depends on efficiency so things like wire size, skin effect, standing waves, and other things matter (see here, for example). With a receive-only antenna it is OK to use very thin wire. Resonance can matter if you want the last ounce of signal strength with an antenna tuner, like in high-Q type loops where the bandwidth is very narrow and you are using a multi-turn loop with variable capacitor and a pick-up coil of wire to the receiver. Comparatively, my simple loop is depending more on a single turn of wire, the aperture size, length of wire for its performance, and carefully isolating the feedline coax using RF chokes at both ends.
Here is one example of a strong station from Cuba I was able to record because WLW was off the air for some unexpected reason.
Radio Reloj, Cuba 870 kHz (At the end, you can hear WLW come back online with CBS news):
Side note about Radio Reloj on Wikipedia, the strange format seems to fit well with a totalitarian regime, including a “corrector” who “corrects the content/writing errors to meet the requirements”. Read the wiki link for yourself. Not a society I want to live in, thank you very much!
Example of 80 meter band performance – Greetings to a new person from members of the “Awful, Awful, Ugly Net”, 3855 kHz:
Encouraged by the results, I “installed” the magnet wire around the support beams of the wooden porch, wrapping it carefully to create a square loop. Holding it in place is a brick at each bottom corner since I am not allowed to nail anything into the Association-owned porch. The length came out to about 32 feet (8 feet per side), so I trimmed it and connected to the balun. I also added an RF choke at the Airspy HF+ input from Palomar Engineers which helped bring noise down a couple of S-units. That might not sound like a lot but by also shutting off the living room air filter and an AC switch with “wall-wart” AC power adapters on it, I was able to reduce the noise a little bit more. There is still a lot of noise from the neighbors, so it is not a perfect situation.
Here are two examples of reception with the outside installation.
Side note about the Radio Newsletter. I stumbled on it when using the YouLoop and found that some of the content is very interesting and informative. Of course it is geared mostly towards amateur radio but some of the news items are of general radio interest as well. It airs 1pm Saturday through 2am Sunday, USA Central Time. Obviously, many segments repeat during that lengthy timeframe and reception depends on propagation from Missouri.
KDDR 1220 kHz, West Fargo, ND station ID (presumably “nighttime” power of 327 watts):
The shortwave bands are still a noisy disaster but signal levels are higher compared to the YouLoop. Only the strongest stations come in like WRMI, WHRI, Radio Espana, Radio Habana, and CRI. And I can hear the loudest amateur radio operators.
Just for grins, here is Radio Rebelde on 5025 kHz when band conditions were above average:
Another phenomenon I am looking into is the reception pattern of a vertical loop. Less than 1/10th wavelength, the null is through the center of the loop. At one wavelength, the null manifests in the plane of the wire loop. They are too close to phase them but switching between two directional loop antennas might improve reception depending on frequency. We shall see in the future.
At least for now, I have a decent mediumwave band which performs better than the useful CCrane Twin-Ferrite amplified loop antenna that was used in the (noisy) indoors, I can hear the 160 & 80 meter amateur bands better, and the reception of the strongest shortwave broadcasters are more predictable. Not bad for four dollars of wire!
Brilliant, Tom! Again, I love how you’ve not only made an inexpensive antenna, but you’ve even done it within your HOA regulations. You’re right, too: if you’re not transmitting into an antenna, it blows the experimentation door wide open! Thank you once again for sharing your project with us.