Many thanks to SWLing Post contributor, 13dka, who shares the following guest post:
The Icom IC-705: Is this really a new holy grail SWL/BCL receiver?
When Thomas got wind of its development in 2019 he immediately asked “could the Icom IC-705 be a shortwave listeners holy grail receiver?”. I usually wince a little when I hear “holy grail” because it means very different things to different people, it’s also a moving target with many people aiming at the spot where it was decades ago. But Thomas certainly had a very level-headed assembly of technical performance, quality and practicality requirements in mind when he used that term, and I thought he might be onto something!
There are some excellent, trustworthy reviews of the IC-705 out there. The following is not one of them, I just want to share an opinionated breakdown on why I think this is an interesting radio for SWLs/BCLs indeed, also deliberately ignoring that it’s actually a transceiver.
While the era of superhet/DSP-supported tabletop holy grails ended with the discontinuation and sell-off of the last survivors more than a decade ago, powerful PC-based SDR black boxes were taking over the mid-range segment and it became very slim pickings for standalone SWL receivers: Thomas just recently summed up the remaining options here.
Between the steady supply of inexpensive yet serviceable Chinese portables, upgraded with a least-cost version of DSP technology, and the remnants of the high end sector there’s very little left to put on the wish list for Santa – that doesn’t need to be paired with a computer that is.
No surprise that SWLs/BCLs in search of new quality toys with tangible controls are taking a squint over the fence to the ham transceiver market: Hams are still being served the best and the latest in radio technology in all shapes and sizes, and even entry-level rigs usually come with feature-rich general coverage receivers. But transceivers never had SWLs much in their focus in the past decades, and particularly not BCLs: Frontend adaptation, additional AM filters, switches and functions would’ve meant increasing costs and so transceivers were never perfected for that purpose. DSP and SDR technology allowed for improvements on that without actually adding (much) hardware and so some interesting alternatives surfaced in the past years, but most of them still come with little downers, at least for BCLs.
I could only keep the TX-500 for a one week evaluation period because it was one of only two or three pre-production units in the US–one was being evaluated for FCC approval.
Often, when a reviewer is sent a loaner unit, if we really like it we can purchase it from the manufacturer for roughly market price. The TX-500 was so rare, though, this simply wasn’t an option. Had it been, I would have purchased it. I liked the radio that much.
This week, I took delivery of a new TX-500 sent directly to me by the manufacturer in Russia. (You’d better believe I’m not sending this one back! I’ve already given it a name!)
I will say this: if you’re a ham radio operator that likes SWLing, the TX-500 is a very capable broadcast receiver. Since I took delivery, I’ve had some pretty long listening sessions with the TX-500 on mediumwave and shortwave. The AM filter width is adjustable and can be quite wide if you want full fidelity. You must use an external speaker or headphones with the TX-500: this portable transceiver is sealed so that it’s weatherproof. The supplied speaker/mic works in a pinch, but I much prefer headphones or one of my amplified speakers.
QRPer.com: the other blog
I realize that many readers here on the SWLing Post aren’t aware that I actually have another blog dedicated to ham radio in the field: QRPer.com.
QRPer and the SWLing Post were actually born around the same time in 2008, but over the years I put much more effort and energy in the SWLing Post as I felt there needed to be better resources, articles, and information out there about radio listening. The SWLing Post has grown to a community of 8,000-9,000 daily readers and I couldn’t be more proud. There are days it really feels like a big, international family of kindred spirits. I’ve learned so much from this community.
QRPer is devoted to low-power amateur radio operation in the field. It has a completely different feel than the SWLing Post as most articles are field reports from my Summits On The Air (SOTA) and Parks On The Air (POTA) activations. I post at least one field report each week and typically test a different pairing of a transceiver and antenna. Many of my activations these days are using CW (Morse Code). After completing my first CW activation last year, I truly fell in love with this earliest of radio modes.
I get that there are many here at the Post that don’t really care for ham radio or QRP operation and that’s perfectly fine. I mention QRPer because I’ve been getting notes from readers who are just realizing that there’s a common connection between the SWLing Post and QRPer: me!
I’m horrible at cross-promoting my work, so there you go.
Not a YouTuber, but I have a YouTube channel
While I’m at it: last year, I also started making real-time, real-life, unedited YouTube videos of many of my QRP field activations. I made some of the first ones at the request of readers who wanted to know what it was like to actually perform field activations.
I’m a fellow who has very little free time and the thought of editing videos, frankly, makes me break out in a cold sweat. I simply don’t have the time. Plus, I don’t really have the personality of a successful YouTuber. I am what I am.
I posted my first unedited videos expecting negative comments. The total opposite happened.
While I never expect my YouTube channel to appeal to anyone beyond a very niche audience, I have gotten some very encouraging comments from subscribers who appreciate (virtually) sitting with me on the park bench or on a 3,000 meter summit and copying the CW and SSB contacts that roll in. I see these videos as supplements to my field reports on QRPer.com. In fact, if you want to see the Discovery TX-500 (mentioned above) in action, you’ll want to read my field reports on QRPer.com and watch the activation videos.
If you’re looking for a proper cure for insomnia, here’s a link to my YouTube channel. Consider subscribing if I haven’t scared you away already. 🙂 Indeed, as I publish this post, I see that I’m almost at the 3,000 subscriber mark. What?
Oh, speaking of YouTube and the TX-500, I made a video shortly after receiving it via DHL. I call it an “unboxing” video but really it’s an excuse to talk about why I’ve missed the TX-500.
By the way: I don’t monetize my YouTube channel, so there are a total of ZERO ads. I’m able to support my radio and blogging life via the backing of my amazing readers and sponsors. Thank you so very much!
Many thanks to SWLing Post contributor, Giuseppe Fisoni, who reached out a few weeks ago noting that he was very impressed with the Icom IC-705‘s receiver performance even compared with his Icom IC-R8600 wideband receiver.
I asked Giuseppe if he would perhaps write up a short informal report to share here on the SWLing Post. He just sent me the following notes:
[…]Consider this more of a qualitative comparison – just S meter readings with a few brief notes.
My overall impression is that the IC-705 is a fantastic SW receiver, as you’ve already made clear on all your posts. In most cases, it holds up well against the IC-R8600, and even performs better in some cases. I have some notes below, which you are welcome to share with your readers if you’d like. For a while I also had two IC-705s in my hands, so I even got to test “replicas” with the 705 (there was no major difference but it was still fun to do).
A few things about my comparisons:
1. All tests were done using a 50’ long wire antenna (house to tree) with an un-un.
2. The IC-R8600 was operated using an ICOM AC adaptor (creating a disadvantage), while the IC-705 was run on battery. However, I tried to only compare stations where the noise floors were comparable and the 8600 didn’t have any RFI.
3. I tried my best to normalize the RF gains on each radio, but this became somewhat difficult. I’m not sure if they are on the same scale (i.e. does 80% RF gain mean the same thing on both radios?). Also, I very quickly noticed that turning up the RF gain on the 8600 only increased the S meter reading and apparent noise floor on the waterfall spectrum, but it did not actually make the audible signal or noise audibly stronger. This was especially true from 50% and up on the RF gain. In contrast, the RF gain on the 705 operated as you’d expect – the more you turned it up, the higher the gain on the signal (and noise), evenly across 0-100%.
3,330 kHz CHU
IC-705: weak signal but audible, S6
IC-R8600: no signal!
Winner: clearly 705. Shocked the 8600 couldn’t pick up CHU!
3,215 kHz WWCR Nashville
IC-R8600: S9+20 to S9+40.
Winner: Tie – although the 8600 had a stronger signal on the S meter, it didn’t really sound any better than the S9+20 on the 705.
9,690 kHz Radio Espana Exterior
IC-705: S9 to S9+10
Winner: Another tie – the stronger signal didn’t make much of a difference. The 8600 only sounded slightly better because of its speaker, not the receiver, so I’m calling it a tie.
10,000 kHZ WWV
IC-705: S3, very weak
IC-R8600: S7 to S9 but high atmospheric noise
11,820 kHz Radio Riyadh
IC-705: S1, barely detectable
IC-R8600: S5 to S7, intelligibility unstable
15,000 kHz WWV
IC-705: S3 to S5
IC-R8600: S9, slightly clearer and crisper tones
Winner: 8600, but not by much
15,580 kHz VOA Selebi-Phikwe, Botswana
IC-705: S1 to S3, in and out with fading
IC-R8600: S9, much more stable signal
7,780 kHz WRMI Slovakia International
IC-705: S9 solid, stable signal
IC-R8600: S9, same
6,604 kHz USB Gander VOLMET
IC-705: S5 to S7
Winner: Tie, no real difference
11,940 kHz Radio Exterior Espana
IC-705: S5 to S9 solid signal with some fading
Winner: Tie – no obvious difference
9,420 kHz Helliniki Radiophonia, Greece
IC-705: S9 +20. Excellent signal
IC-R8600: S9+ 20-30. Excellent signal
Winner: Again, a tie. But the wonderful Greek music reminds you again how much better the speaker is on the 8600.
Here’s the important thing: even though in most cases the IC-R8600 pulled in a much higher S meter reading, it often didn’t matter unless the difference between the two radios was a lot. In cases where it mattered, I could have turned up the RF gain or preamp on the 705 to match the signal on the 8600 (unless it was really weak on the 705), but I was trying to avoid that for the sake of having some baseline for comparison. How comparable are RF gain levels across ICOM radios?
IC-705 pros/cons take aways for me:
High level of portability and ability to operate on battery
Has desktop-like features and controls
Ability to use tripod or custom stand offers custom ergonomics (I found it easier to look at and interact with than the 8600, which has a lower angle of display)
All-in-one package: SWR + HF/VHF/UHF transceiver
Built-in audio speaker leaves a lot to be desired, definitely not desktop receiver audio quality
No stereo headphone jack
I am quite impressed with the IC-705! I am looking to downsize my radios and these comparisons have convinced me that the 705 can really check a lot of boxes for what I am looking for in a radio. I think it really offers a lot in a small footprint, which I find very impressive. So, since I have no use in monitoring anything above UHF, I will be looking to sell the IC-R8600, even though it is also a very great radio.
All the best,
Fascinating report, Giuseppe! Thank you so much for taking the time to perform these comparisons and sharing them with us.
Like you, I believe the IC-705 could replace a number of my other radios. I originally purchased it for my review and planned to sell it after, but quickly realized there’s no way I’m selling it. In fact, it could convince me to sell other radios it effectively makes redundant.
For SWLs who have limited space for a listening post in their home and who like to take their radio to the field, the IC-705 is a no-brainer. It’s an investment at $1,300 US, but I believe it’s a quality rig and certainly an outstanding, feature-packed unit.
I’ve found that the IC-705’s performance on HF and Mediumwave is truly DX-grade. I imagine its FM performance is as well.
It’s funny that you mention the IC-705 front-facing speaker as a con, because I often tout it as a pro. Thing is, I’m most often comparing the IC-705 with other field-portable QRP transceivers. Compared with them, the IC-705 speaker is amazing. But compared to the IC-R8600 or, say, a Drake R8B or SW8? Yeah, I agree with you 100%–it’s just not in the same league with those tabletop receivers. Of course, you can port out the audio to a better speaker if needed. (Indeed, the IC-705 even has built-in Bluetooth!)
Thanks again for sharing your notes with us, Giuseppe!
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:
Wow, Mark! I do love the size of this case and the fact that it fits the FT-891 so perfectly.
Recently, I’ve been thinking about building out a case to hold one of my smaller QRP transceivers (the KX1, KX2, or MTR3B) in the field to be used when it’s raining. Perhaps this has been on my mind because I’ve been enjoying nearly 5 straight days of rain and fog! A case like this would be an affordable solution and I wouldn’t feel terribly bad about drilling through the case to mount antenna, key, mic, and headphone ports.
I, for one, would love your thoughts about the Yaesu FT-891 as well. I’ve contemplated reviewing it this year mainly because so many field operators rave about it. I’d be curious what you think about it in terms of shortwave radio listening.
Thank you again for the tip!
Note that the Amazon affiliate links above support the SWLing Post at no cost to you. If you’d rather not use these links, simply search Amazon for “Max MAX004S.” Thank you!
In 2019, shortly after Icom announced the Icom IC-705, I speculated that this rig might be a contender for “Holy Grail” status.
I must admit…the more I use this radio, the more I love it. It is a proper Swiss Army Knife of a radio. Even though I’ve owned and operated it for a few months, I still haven’t explored all that it can do, and I keep finding features I love.
After completing the upgrade, I hooked the ‘705 up to my main antenna and worked a few Parks On The Air (POTA) stations off of the supplied battery pack (instead of a power supply). While I worked on other projects in the shack, I checked the POTA spots and work a few stations with a whopping 5 watts of output power.
After a couple hours on the air (mostly listening), the internal battery pack still had a good 60-70% capacity.
At one point, I tried a little daytime mediumwave DXing and cruised past 630 kHz which some of you might already know is the home of one of my favorite hometown radio stations, WAIZ.
From my home, WAIZ is a tough catch, so it was weak, but I could hear it.
This reminded me that I had made a recording of WAIZ with the IC-705 when in my hometown earlier this month.
Normally, I pull the MicroSD card out of the IC-705–which almost requires needle nose pliers and is one of my few complaints about this rig–and view the files on my PC or MacBook, but I was curious if perhaps the IC-705 software had a built-in file display.
Of course it does!
Simply press the MENU button, then the RECORD button on the touch screen, and you’ll see the following selections:
Press “Play Files” and you then see a list of folders organized by date:
Click on a folder and you’ll see a list of recordings made that day:
These are some of the most important pieces of information I use to index my audio recordings and the IC-705 does this automatically. In fact, if you allow the IC-705 to gather its time information from the internal GPS, the time stamp will be incredibly accurate.
The only thing I add to the file name after export is the broadcaster name/station callsign.
If that wasn’t enough, if you touch one of the recording files, the IC-705 will open it in an audio player:
The built-in player displays the meta data, and even includes a number of controls like fast-forward, rewind, skip to next or previous file. and pause.
I’m sure this is the same audio player found in the IC-7300, IC-R8600 and other late-model Icom SDR rigs. But in a portable battery powered transceiver? This is a genius feature.
As I type this post I’m listening to the audio from the WAIZ file shown above. I can imagine when I’m able to travel again (post-pandemic), how useful this will for one-bag air travel.
Not only is the IC-705 a QRP transceiver and wideband multi-mode general coverage receiver, but it’s a recorder and audio player with a built-in front-facing speaker. I can set this transceiver at my hotel bedside and listen to recordings I made in the field earlier that day or week.
Keep in mind that the IC-705 is an expensive radio–certainly one of the most pricey QRP radios ever produced at $1,300 US (at time of posting although I’m sure we’ll start seeing lower pricing this year). But if you’re an SWL and ham, you’ll find the IC-705 is the most versatile portable transceiver on the market. If you’re an SWL only, you can disable the transmit on the IC-705 and essentially have a portable battery-powered SDR receiver with built-in audio recording and playback with color touch screen spectrum and waterfall display.
Despite the price, this is Holy Grail territory in my book.
Icom IC-705 Review
If you subscribe to The Spectrum Monitor magazine, you’ll be able to read my (4,000 word!) review of the IC-705 in the upcoming February 2021 issue.
Many thanks to SWLing Post contributor, Kostas (SV3ORA), for sharing the following guest post which originally appeared on his radio website:
Emergency transmitter: An 8-component, high-power 40m/30m transmitter to get you quickly on the air
by Kostas (SV3ORA)
QRP is all about doing more with less. This is more than true, with the construction of this cheap, simplistic transmitter presented here. It is designed primarily as an emergency transmitter (EMTX) that can be built or serviced in the field or at any home. However, it can be used as a HAM radio transmitter as well. Do not judge by its low components count though. This transmitter is powerful, more powerful than anything the QRPers would dream of. It is just remarkable how 8 components can lead in so much output power, that lets you communicate with a big part of the world, when propagation conditions are right. It is very difficult for a circuit to match that kind of simplicity in balance with such performance.
Following my detailed instructions, the EMTX can be reproduced easily, within hours. The result is always success, this is one of the circuits that are not critical at all and a successfully working transmitter can be reproduced every time. I have built this transmitter several times, using similar components (even toroids) and it always worked. The transmitter meets the next expectations:
1. Output power (including harmonics): A few mW up to 15W (depended on transistor, crystals and voltage/current used) at 50 ohm.
2. It can drive any antenna directly, 50 ohm or higher impedance, without external tuners.
3. Bands of operation: Currently 40m, 30m
4. Mode: CW, Feld-Hell (with external switching circuit), TAP code and any other ON/OFF keying mode. AM modulation has been easily applied too.
5. Options like reverse polarity protection diode (useful in the field when testing different unknown polarities PSUs) and current meter (for easier tuning) are available.
The purpose of this transmitter is to be used primarily as an emergency transmitter. This poses several challenges that influence the design of the transmitter:
1. It must be able to be built or serviced easily in the field or at any home, with components that could be salvaged from near by electronics sources or a small electronics junk box. This means that components count should be kept very low and they must not be rare to find but commonly available parts. As a side effect cost would also be kept small, if one is to buy any component. Also, the active components must be interchangable with many other devices without the need for the design or the rest of the circuit components to be changed.
2. It must be able to operate from a very wide range of DC voltage sources and at relatively low current, so that common house power supplies could be used to supply power to it. Such devices include linear or switched mode power supplies from laptop computers, routers, printers, cell phone chargers, Christmas lights or any other device one might have available.
3. It must be capable of transmitting a powerful signal, so that communication is ensured. An emergency transmitter that is capable of a few mW of output power, might be heard locally (still useful, but there are handheld devices for that already) but isn’t going to be of much usage if it can’t be heard really far away.
4. It must be capable of loading any antenna without external equipment required. In an emergency situation, you just don’t have the luxury of building nice antennas or carrying coaxial cables and tuners. There may be even extreme cases where you can’t even carry a wire antenna and you depend on salvaging wire from sources in the field to put out a quick and dirty random wire antenna.
5. Adjustments of the transmitter should be kept minimum without the help of any external equipment and there must be indication of the correct operation of the transmitter or the antenna in the field.
This transmitter has been designed so that it can operate with any NPN BJT in place. This includes small signal RF and audio transistors and high power RF transistors like the ones used on HF amplifiers and CB radios. Despite 2sc2078 is shown in the schematic, just try any NPN BJT in place and adjust the variable capacitor accordingly. When you are in the field, you do not have the luxury of finding special types of transistors. The transmitter must operate with any transistor in hand, or salvaged from near-by equipment. Of course the power capability of the transistor (as well as the crystal current handling) will determine the maximum VCC and current that can be applied to it and hence the maximum output power of the transmitter. Some of the most powerful transistors I have used, come out of old CB radios, such as the 2sc2078, 2sc2166, 2sc1971, 2sc3133, 2sc1969 and 2sc2312. There are many others. As an example, the 2sc2078 with a 20v laptop PSU, gave 10-12W of maximum output power into a 50 ohms load.
Schematic of the 8 components EMTX for the 40m/30m bands. Components with gray color are optional.
This is the most uncommon part of the transmitter. You have to find the crystal for the frequency that you want to operate on. Crystals within the 40m or 30m CW segments are not that common. Further more if you operate the transmitter at high powers and currents, you will notice crystal heating and chirp on the frequency of the transmitter. The current handling capability of your crystal die inside the crystal case, will determine the chirp and the amount of crystal heating. You can still work stations with a chirpy transmitter provided that the chirp is not that high, so that it can pass through the CW filters of the receivers. However, if a small chirp annoys you or if this chirp is too much, then you have to use these vintage bigger size crystals (e.g. FT-243), that can handle more current through them. But these are even more uncommon today.
The approach I have used in my prototype, was to connect more than one HC-49U crystals of the same frequency in parallel, so that the current is shared among them. This reduced the chirp at almost unnoticeable levels, even at high output power, just if I was using a single FT-243 crystal, or even better in some cases. Again, this is optional, but if you want to minimize chirp (and crystal heating) without searching for rare vintage crystals, this is the way to go.
A bit of warning. If you notice a very high chirp when plugging in a crystal to the EMTX, you should consider this crystal as inappropriate for this transmitter, as it cannot handle the current required. If you continue to use this inappropriate crystal, you could easily crack it inside and set it useless. Don’t use these tiny HC-49S crystals, they won’t work.
The current meter:
A 1Amp (or even larger) current meter can be used to monitor the current drawn by the transmitter during key down. The recommended current operating point is anywhere between 450mA to 1A, depended on the output power (and harmonics) level you want to achieve. The current point is set by the variable capacitor. I would avoid setting the current to more than 1Amp, although it can be done. The use of the current meter is optional, but along with the incandescent bulb, will give you a nice indication of the correct tuning of the transmitter, so that you do not need to have an external RF power meter connected to the transmitter output. If you do have, then you can remove the current meter. If you don’t have a 1Amp analogue meter available, but a smaller one, you can parallel a low value power resistor across the meter. In my case, I only had a 100uA meter and I paralleled a 0.15 ohms 5W resistor across it to scale down 1Amp to 100uA, The resistor value depends on the internal meter resistance so you have to calculate this for your specific meter. When the 2sc2078 is used at 20V, 500mA in the current meter indicates around 5W of output power, 600mA indicates around 6W, 700mA 7W, 800mA 8W, 900mA 9W and 1A around 10W. So the current meter can be used as sort of power meter without the need to do any scaling on it.
The incandescent bulb:
A current meter alone, without the use of the incandescent bulb, will not give you the right indication of the operation of the transmitter. In some cases, the transmitter might be drawing current without actually generating much, or even any RF. When you are in the field you do not want to carry extra monitoring equipment with you. The incandescent bulb will light on when the transmitter oscillates. It monitors the actual RF signal, so it’s brightness changes according to the amount of RF power the transmitter produces. Along with the current meter reading, this is just what you need to know in order to set the variable capacitor properly. Note that the bulb will not lit at very low signal levels. The one used in the prototype starts to glow up from a bit less than 1W. Miniature incandescent bulbs may not be that easy to find nowadays. However, there is a good source of these, that almost anyone has in their houses. This source is the old Christmas lights. You do save old Christmas lights, don’t you? The incandescent bulb indicator as well as it’s single turn winding on the transformer, are optional components. If you have an RF power meter connected to the transmitter, you can remove these.
The protection diode is an optional component to the circuit. If you are in the field, correct polarity of a power supply may not be obvious. Without a multimeter it might me difficult to determine the correct polarity of the PSU. A power diode (I used a 6A one) will protect the transistor from blowing up in the event that reverse polarity is connected to the circuit.
The Cx and Cy:
The Cx and especially the Cy capacitors need to be of good quality. The Cy will get hot on high output power if it isn’t. In the tests, I have used homemade gimmick capacitor and even double-sided PCB as a capacitor for Cy and they all got hot at high power. Silver mica capacitors run much cooler and they do make a small difference in the output power, so I suggest to this type. Cy must be able to handle quite a lot of voltage, so silver mica type is ideal.
The variable capacitor:
The variable capacitor can be air variable or ceramic, although I prefer air variables in tis application. In any case it must be able to handle a high voltage just as the Cy.
The key directly shorts the transistor emitter to the ground, therefore it is a part of the active circuit. For this reason, I suggest the key leads to be kept as short as possible. The key must be able to handle the voltage (20v) and current (up to 1A) on its contacts, which is usually not a big deal.
The construction of the transformer is shown below step by step. Note that if you decide that you don’t need to drive higher impedance loads but just 50 ohm ones (eg. antenna tuners or 50 ohm matched antennas), you just need to wind 2t in the secondary and not 14t. You also don’t need any taps of course.
Take a piece of 32mm external diameter PVC pipe from a plumber’s shop. Alternatively, a suitable diameter pills box can be used, or any other suitable diameter plastic tube.
Cut a 4cm piece out of this tube. 4cm is the minimum length required.
Below a 4cm PVC tube has been cut in size.
Wind 16 turns of 1mm diameter enameled wire onto the PVC pipe and secure the winding in place as shown in the picture below. Notice the winding direction of the wire. This is the primary of the transformer, the one that is connected to the two capacitors. Notice that this winding is wound a bit offset to the right of the pipe.
Wrap the winding with 3 turns of PTFE tape. It can be bought at any plumber’s shop, just like the PVC pipe. The PTFE tape will help in keeping the second layer turns in place and it will provide extra insulation.
Wind 2 turns of 1mm diameter enameled wire on top of the primary winding and secure the winding in place as shown in the picture below. Notice the winding direction of the wire, as well as it’s position relative to the primary winding. This is the feedback of the transformer, the one that is connected to the collector of the transistor.
Wind 14 turns of 1mm diameter enameled wire on top of the primary winding, starting from just next to the 2 turns one and secure this winding in place as shown in the picture below. Notice the winding direction of the wire, as well as its position relative to the primary and the 2 turns windings. This is the secondary (output) of the transformer, the one that is connected to the antenna. At this point do not worry about the taps yet.
Notice in the picture below, the way the windings are secured in place onto the pipe. The wire ends are passed through the pipe using small holes and then bent towards the ends of the pipe and once more to the surface of the pipe, where the connections will be made.
Wind 1 turn of 1mm diameter enameled wire onto the pipe and secure the winding in place as shown in the picture below. Notice the winding position relative to the other windings. This 1 turn winding is placed about 1cm away from the other windings. This is the RF pick up winding, the one that is connected to the incandescent bulb.
Use a sharp cutter (knife) and carefully scrap the enamel of all the windings ends. Do not worry if you cannot scrap the enamel at the bottom side of the wire ends (that touches to the pipe). We just want enough copper exposed to make the connection.
Tin the scrapped wire ends, taking care not to overheat them much.
Now it’s time to make the taps on the secondary winding. Use a sharp cutter (knife) and very carefully scrap the enamel of the wire at the tap points (number of turns). Take much care not to scrap the enamel of the previous and the next turn from each tap point. Do not worry if you just scrap the enamel at the top of the wire (external area). We just want enough copper exposed to make the connection.
Make each tap, a bit offset from the near by taps, like shown in the pictures. This will avoid any short circuits (especially at the 4, 5 and 6 taps) and it will allow for easier connections, especially if alligator clips are used to connect to the taps.
Tin all the tap points, taking care not to overheat them.
This step is optional and it depends on how you decide to do the connections to the taps. You may solder wires directly to the tap points, but in my case I wanted to use alligator clips, so I did the next: I took a piece of a component lead and soldered it’s one end to each tap point. Then I bent the component lead to U-shape and cut it accordingly. This created nice and rigid tap points for the alligator clip.
This step is optional and it depends on how you decide to mount the transformer to your enclosure. In my case, I wanted to create three small legs for the mounting. I cut three pieces of aluminum straps and made holes at both their ends. I made three small holes onto the transformer pipe end and mounted the aluminum straps using screws. After mounting them, I shaped the straps to L-shape. Then I used three more screws to mount the transformer to the enclosure.
The completed transformer is shown in the pictures above and below. The 6 connection points at the bottom of the pipe, are the low voltage points, whereas the 2 points at the top of the pipe, are the high voltage points.
If you have built the transformer as described, the bottom connections are as follows (from left to right):
Wire end 1, connected to the incandescent bulb
Wire end 2, connected to the incandescent bulb
Wire end 3, connected to the current meter
Wire end 4, connected to the current meter
Wire end 5, connected to the GND (ground)
Wire end 6, connected to the transistor collector
The top connections are as follows (from left to right):
Wire end 1, connected to the 25pF variable capacitor and the Cy fixed.
Wire end 2, is the 14th secondary tap and it is left unconnected, or tapped to the appropriate impedance antenna.
Videos of the EMTX in operation
I have made two small videos of the EMTX in operation.
The first 13.5MB video (right click to download), shows the operation when the transmitter is set for a bit less than 10W of output power.
The second 3.5MB video (right click to download), shows the operation when the transmitter is set for about 5W of output power.
EMTX chirp analysis
Every self-exited power oscillator (and even many multi-stage designs) exhibits some amount of chirp. Chirp is mainly considered as the sudden change in frequency when the power oscillator is keyed down. Apart from chirp, there is also the longer term frequency stability that may be considered. The chirp in the EMTX is surprisingly low, if it is built properly. Hans Summers, G0UPL has performed a chirp analysis on my EMTX (PDF) and the EMTX built by VK3YE and presented on YouTube. Hans, performed the analysis from the video/audio recordings of both transmitters. I sent him two videos, one with the EMTX set for an output power of 10W and one where it is set for 5W. The chirp at worst case (10W) was about 30Hz and at 5W in the order of 10Hz or so. Being so small, the chirp is almost undetectable by the ear and it surely poses no problems when passing the tone through narrow CW filters. This is an amazing accomplishment from a transmitter so simple and so powerful.
EMTX harmonics measurement
Every unfiltered transmitter will excibit harmonics at it’s output. This means that the output waveform has some distortion in comparison to a pure sinewave. Many of the transmitters I have seen, present a very distorted output waveform and absolutely need a LPF if they are to be connected to an antenna. I can’t say that this is true for the EMTX, because surprizingly, it has low distordion, despite the high output power it can achieve. Although a LPF is always a good idea, it is not that much needed on the EMTX. However you have to use one to comply with the regulations.
The image above, shows the measurements on the output of the EMTX, when it is set closely to 10W at 50 ohms. The main carrier is exactly at 9.9W and all the harmonics are less than 50mW! Also, the harmonics, do not extend into the VHF region.
The image below, shows the measurements on the output of the EMTX, when it is set closely to 5W at 50 ohms. The main carrier is exactly at 5.17W and all the harmonics are less than 9.6mW! Again, the harmonics, do not extend into the VHF region.
These small harmonics levels aren’t going to be heard very far at all, compared to the powerful carrier. This means only one thing. A LPF, although a good practice, is not mandatory in this transmitter. But you should better use one so that you comply with the regulations.
Many HAMs use just a watt meter to measure the output of their homebrew transmitters. This is not the proper way of doing it, because the watt meter is a non-selective meter. It will measure both the fundamental carrier and the harmonics, without being able to distinguish them. So in an unfiltered transmitter, or in a transmitter with a simple (often non measured) LPF, this way will give a totally false reading of the output power of the transmitter at the set frequency.
The proper way of accurately measuring the output power of a transmitter and the harmonics levels, is a spectrum analyzer. The FFT available in many modern oscilloscopes, having a dynamic range of approximately 50-55dB, is adequate for this purpose as well. A 50 ohms dummy load must be connected at the transmitter output and then the high impedance probe of the scope, is connected to the output of the transmitter as well. This was the way that the above measurements have been performed.
Here are some test transmissions, to determine how far one can get with such a transmitter. I have to say that there is an antenna tuner between the EMTX and my inefficient short dipole (not cut for 40m and not even matched to the coaxial). However I could still cover a distance of more than 2500Km even on the 5W setting.
A screenshot of the transmitter signal, as received on a WebSDR 2500Km away and when the EMTX is set for an output power of 10W.
Below, is a picture and an audio recording of the transmitter signal, as received on the same WebSDR and when the EMTX is set for an output power of 5W.
Pictures of the finished transmitter. You don’t have to build it that nice-looking if you don’t care.
EMTX prototype built on a breadboard. Yes it worked just fine onto a piece of wood.
This is a phenomenal project, Kostas. Thank you so much for sharing it with us. I love the simplicity of this design–truly form following function. With a little patience, anyone could build this transmitter.