Many thanks to Alex (W3AVP) who shares this photos of his homemade cootie/sideswiper originally posted on the POTA Faxcebook page. Alex notes:
I didn’t want to lug my Begali key to the parks so I made my own using the plans from KA8VIT. Worked great! I had a little QRP key but my fat fingers would make so many mistakes. The DIY aspect of this hobby is extremely entertaining!
And I bet your “cootie” serves you well in the field! I love the simple design and the fact it even has an adjustable action. At the end of the day, keys are merely switches so are perfect for homebrewing!
If you have a sideswiper/cootie or any other key you’ve built and would like to share it here on QRPer, contact me (K4SWL at QRPer.com).
This weekend, both of my middle school-aged daughters passed their amateur radio exams with colors flying. Volunteers with the WCARS VEC were kind enough to meet us at a local park to conduct the test in a covered picnic area.
At the test site I was more nervous than my girls were, but I really had nothing to fear. Both were hitting a 95% pass rate on practice exams in advance.
Even though the girls have obviously learned a bit about radio through osmosis in this household, they did all of the exam prep on their own. Funny story: I remember allowing them both to send CW to my buddies K8RAT and WD8RIF on my lap when they were maybe 2 years old? Of course, they had no idea what they were sending, but they loved playing with the “clicky thing” (my paddles). I think WD8RIF actually copied their code to paper. 🙂Â
I purchased both of them an FT-60R handheld radio from Universal Radio. I think these HTs should serve them well for many years to come!
I know one of my daughters is already chomping at the bit to pass her General now.
Anyway, thanks for letting me brag a bit here. I’m certainly a proud papa!
Practicing left hand lunching, right hand keying/logging!
It seems like lately I’ve had to work hard to log 10-15 contacts during my Parks On The Air (POTA) activations. Propagation has been so flaky, I use every trick in the book to snag at least my ten contacts for a valid activation: change antenna configuration, run up to 40-50 watts output, employ both CW and SSB, have friends spot me on the network, and try every band possible (typically from 80-17).
Note that the majority of my activations are proper QRP and rarely do I spend longer than 60 to 90 minutes actually on the air. Indeed, many of my activations are only 60 minutes long including set-up and take-down. That may seem short to most POTA folks, but that’s what works in my schedule and family life: quick hits. It’s one of the reasons I’m not more active in Summits On The Air (SOTA)–I need more time for those sites as they’re not as accessible as our numerous POTA entities.
Still, our local star has been misbehaving, and I had not planned to do an activation on Sunday (September 28) because I saw the propagation forecast and it was rather discouraging (A index 26, SW 505, Bz -2).
From home that morning, I chased a few parks but found it challenging to hear most of them. QSB was incredibly deep–strong stations gone in an instant.
Still, my wife suggested we take a picnic to one of our favorite local spots and how could I possibly visit a park without activating it? Right–?
Zebulon B. Vance Birthplace (K-6856)
What we, as a family, love about this site is the large covered picnic area and historic log cabins. Also, the site receives very few visitors on Sundays when the main museum is closed.
Each time we visit the Vance site, we bring my MSR liquid fuel stove and make lunch/dinner.
I set up the stove, got lunch started and my wife took over food prep.
Knowing propagation was unstable, I opted for more than QRP power this time–at least, at first–so I chose the Mission RGO One transceiver (capable of 55 W output) and CHA Emcomm III Portable antenna for this activation.
I deployed the Emcomm III in a sloping configuration with the end of the 73′ radiator high in a nearby (dead) tree and the counterpoise on the ground. I also suspended the winder/balun from the corner of one of the shelter’s rafter’s with paracord.
Since it’s difficult to see a wire antenna in photos, I’ve labeled the components in the following image (click to enlarge):
I didn’t know if this configuration would prove useful, but I knew it would be better than attempting this activation with my Wolf River Coils TIA vertical antenna.
I hopped on the air starting on 80M CW (at the request of my buddy WD8RIF), worked him and three stations in rapid succession. After a few minutes of silence, I moved up to the 40 meter band and worked 16 stations. I then moved to 30 meters and worked 11 stations.
I was working more stations than I would have ever guessed beforehand.
Since I only had about 10 minutes to spare after working 30 meters, I decided to plug in the microphone and work some park-to-park contacts. While I always intend to hunt for other parks while I’m in the field, more times than not, I don’t have the luxury of an Internet connection to check the POTA spots page like I did at Vance on Sunday.
I must say, I really love the CW Morse double paddles. They’re fully (and easily) adjustable, the action is responsive and smooth, and with the base, they’re incredibly stable on a hard surface. I highly recommend them.
At a setting like we had at Vance, I love the heavy base plate, but if I planned to hike into a site, I believe I’d remove the base to save on weight.
Unpredictable Propagation?
Perhaps there was a brief window of stability between solar events and I was able to take advantage of that while I was on the air? I’m not sure.
I never expected to log 37 contacts in the space of a little over an hour (with some of that time being off the air to help with picnic prep). Not on that Sunday when the solar numbers were in the dumps.
I’d like to believe it was a combination of things:
A large wire field antenna with decent gain and the ability to work multiple bands
40 watts of power (at first, I backed down to QRP on 30 meters)
Using CW for 34 of the 37 contacts
Perhaps unintentionally good timing
All I know is, I had a blast! It’s hard to beat a combination of good radio, good food, good scenery, and good weather!
I suppose this was also a lesson in simply hitting the field and ignoring the propagation.
Or as Rear Admiral David G. Farragut once famously said, “Damn the torpedoes, full speed ahead!”
Many thanks to Pete (WB9FLW) who shares the following article by Bob (KD8CGH) regarding the uSDX transceiver kit.
I reached out to Bob who has kindly given me permission to share his article on QRPer:
An Introduction to the uSDX
by Bob Benedict (KD8CGH)
There is a new open source, home brew multi band, multi mode QRP transceiver that grew out of the QRP Labs QCX. Through some serious wizardry it retains an efficient class E RF amplifier for SSB and digital modes. It crams impressive SDR capabilities into an Arduino.
This has an interesting international development process conducted on https://groups.io/g/ucx/topics with contributions by many, including the usual gang of suspects: Hans Summers G0UPL, Guido Ten Dolle PE1NN, Barbaros Asuroglu WB2CBA , Manuel Klaerig DL2MAN, Kees Talen K5BCQ, Allison Parent KB1GMX, Jean-Marie T’Jaeckx ON7EN, Ashhar Farhan VU2ESE, and Miguel Angelo Bartie PY2OHH. I apologize to the many others whose names I didn’t list. A summary is in the WIKI https://groups.io/g/ucx/wiki.
The basic work uSDX appears to have been accomplished by Guido Ten Dolle PE1NNZ. It uses pulse width modulation of the PA supply voltage to transmit modes other than CW while retaining class E efficiency and uses a direct conversion SDR receiver.
The basic idea behind Class E nonlinear amplifiers is that transistors have little loss when they are switched fully on or off. The losses occur when devices are limiting power flow in linear amplifiers. The idea behind a Class E amplifier is to use transistors in a switching mode to generate a square wave to drive a resonant circuit to generate RF power.
This method is used in the popular QCX QRP CW transceiver kit line developed by Hans Summers and sold through QRP Labs https://qrp-labs.com/. More than 10,000 of these great transceiver kits have been sold (I built one). There is a good discussion of the circuit and particularly of the class E amplifier in the excellent QCX documentation https://www.qrp-labs.com/images/qcx/assembly_A4-Rev-5e.pdf.
The QCX was the base for the QCX-SSB which starts with a QCX and modified the circuit and software to add SSB capabilities. The wizardry that Guido accomplished uses pulse width modulation of the PA supply voltage to control the amplifier in an Envelope Elimination and Restoration (EER) technique https://core.ac.uk/download/pdf/148657773.pdf. To generate SSB a DSP algorithm samples the audio input and performs a Hilbert transformation to determine the phase and amplitude of the complex signal. The phase changes are transformed into temporary frequency changes which are sent to the clock generator. This result in phase changes on the SSB carrier signal and delivers a SSB-signal with the opposite side-band components is attenuated.
On the receive side a direct conversion SDR receiver is used with the I and Q signal digitized and all further processing carrying out digitally. Attenuators are included to help not overload the ADC range. Documentation is at  https://github.com/threeme3/QCX-SSB . In addition to a good description of the theory and hardware mod there is also a good description of the software command menu.
From there development took off in several directions. One is by Barbaros Asuroglu WB2CBA  and Antrak that uses through hole components (mostly) and replaceable band boards that hold the low pass filter and band dependent class E amplifier components (an inductor and capacitor). Barb also includes boards designed to be a case top and bottom, battery pack and a PA.
I built the variant designed by Barbaros Asuroglu WB2CBA  and I’m pleased with it’s performance. I ordered 10 main boards and 40 LP filter band boards PCBs from PCBWAY, but now you can also purchase single boards sets from https://shop.offline.systems/.
In an example of hams collaborating at its finest, Hans Summers announced on 9/11/2020 that his new QCX mini product, a QCX in a smaller package, will include a daughter board that can be used to give the QCX mini a uSDX like SSB capability. The QCX mini has the same circuit as the QCX but uses SMD components packaged it into a two board stack that is less than half the volume of the original QCX. The mod is unsupported by QRP-LABS but may be supported by the uSDX group.
Weather in North Carolina has been absolutely stunning over the past week, with the exception of two days where the remnants of Hurricane Sally dumped torrential rain. Two cold fronts provided us with gorgeous clear skies and dry conditions before and after Sally’s visit.
Of course, what better way to enjoy the outdoors than taking my radios to the field?
Last Wednesday, after several hours of knocking out home projects, my wife and I decided to enjoy the fall-like weather and get lost in Pisgah National Forest. My daughters were also keen for a little outdoor adventure, waterfalls, and hiking.
And our canine family member, Hazel? Always up for an outing!
“Let’s go, daddy!”
Of course, my wife was throwing me a bone as she knew I was chomping at the bit to try the new-to-me Chameleon Emcomm IIIantenna.
CHA Emcomm III antenna
Photo Source: Chameleon Antenna
I decided I’d pair the Emcomm III with the amazing Mission RGO One transceiver (a rig I’ll be reviewing in an upcoming issue of The Spectrum Monitor magazine).
Up to this point, I’d never used a Chameleon antenna in the field.
Chameleon Antenna kindly sent me both the CHA Emcomm III and CHA P-Loop a couple weeks ago for an honest field evaluation (and disclaimer: at no cost to me).
And being honest? The overall length of the Emcomm III wire antenna was intimidating. I’m used to field-ready wire antennas that are perhaps 30-41 feet in total length. The Emcomm III has a 73 foot long radiator and 25′ counterpoise! Holy smokes!
In my head, I imagined the only places I’d be able to use the Emcomm III would be in an open park with large, widely-spaces trees.
Turns out, I was wrong.
Two things make deploying the Emcomm III a breeze–even in the middle of a forest:
1.) An arborist throw line: this piece of kithas revolutionized my field antenna deployments. Not only does it give me the ability to suspend antennas much higher than I could before, but also to raise/lower antennas with ease compared with fishing line.
2.) The Emcomm III also has a floating dielectric ring on the radiator wire that allows you to create a suspension point. In fact, there are a number of ways you can deploy the Emcomm III which, I see now, makes it such a popular antenna among POTA operators.
To the field!
The first activation was actually a “two-fer”–meaning, two geographically-overlapping POTA park entities.
Wednesday, September 16: Pisgah National Forest (K-4510) & Pisgah Game Lands WRC (K-6937)
Propagation conditions on Wednesday were so crappy I found myself breaking with QRP to run 40 watts with the Mission RGO One into the Emcomm III. (The Emcomm III can actually handle up to 50 watts CW, 100 watts SSB.)
I first deployed the Emcomm III by pulling the radiator over a tree branch about 50′ high with the balun and winder near the ground. I then unrolled the counterpoise stretched out on the ground.
After only snagging about eight contacts in 50 minutes (a very meager amount for the typical park activation), I decided to re-configure the Emcomm III Portable so that it would act more like a NVIS antenna and perhaps grab a few regional hunters on 80 meters. There was no way I was leaving the forest without my 10 contacts to validate the activation!
I reeled in the radiator and re-attached my throw line to the floating loop and reconfigured the antenna to roughly match this “V” shape with a lower (roughly 25 ft) apex point:
NVIS “V” configuration (lifted from the CHA Emcomm III Portable product page)
I used the RGO One’s internal ATU to match the 80 meter band 1:1.
I started calling CQ on 80 meters CW and, evidently, the POTA site auto-spotted me via the Reverse Beacon Network (RBN) because within a minute, I found myself at the other side of a mini pile-up! I very rapidly worked 8 stations–most of them were in nearby Tennessee. These were callsigns I was not used to logging because typically they’d be under my skip zone–a little too local.
It was nice to get solid copy on 80 meters without the deep QSB on 40, 30 and 20 meters.
The thing that struck me about the Emcomm III at this first activation was how easy it was to reconfigure in the field despite the lengthy radiator. The wire is Copper Clad KEVLAR PTFE (Telflon-coated) and doesn’t easily tangle. It slides so easily through the trees–there’s no coil or bulky bits to get caught in the limbs.
When packing up, it wraps around its built-in winder very easily. Kudos to the designer.
Saturday, September 19: Pisgah National Forest (K-4510) & Pisgah Game Lands WRC (K-6937)
Last Saturday, I wanted to try the CHA Emcomm III in a different region of Pisgah National Forest and see how well it might pair with my Elecraft KX2.
We found an ideal spot to set up: a forest service road that had obviously been closed the entire season.
I deployed the Emcomm III Portable in the same “V” configuration as I did during the first activation, but this time raising the apex of the “V” up to 45 feet.
It’s important to note here that being a random wire antenna, the Emcomm III relies an an ATU to get good matches on each band. The Mission RGO One’s internal ATU did a brilliant job finding matches and, turns out, my KX2 did as well.
In fact, before I started calling CQ, I moved across the bands to see if I could get good matches with the KX2 ATU. From 80-20 meters, I think the highest SWR I had was 1.3:1. (The KX series ATU is truly a benchmark in my book!)
That day, even though the weather was gorgeous, propagation was terrible. I read a few reports from experienced POTA and SOTA folks who couldn’t snag the needed 10 contacts for a valid activation earlier that day. There were contests and QSO parties on the bands so lots of signals–but more than once on the phone portion of the 40 meter band, I could hear two stations calling CQ on the same frequency and trying to work the same stations totally unaware of each other. Not a good day to play radio in the field and was starting to wonder if I could even snag my needed ten contacts.
Turns out, I had nothing to fear.
Since I could, quite literally, pick any band the KX2 could transmit on, I was able to float across the HF spectrum, call CQ, and the RBN would make sure I was spotted properly to the POTA network.
Getting that first ten is a great feeling!
I pretty effortlessly snagged my ten, and then a number to boot.
When I seek a spot to set up in a national forest, I often look for forest service roads with locked gates. When I set up on an unused road, it typically means I’ll have a high branch to hang the antenna and also a little space to deploy it without touching other trees. Our spot on Saturday was ideal.
Again, hanging and deploying the Emcomm III was effortless. I did bring about 12 feet of paracord with me this time allowing me to tie off the end of the radiator if I chose the “V” shape.
Monday, September 21: Mitchell River Game Land (K-6926) & Stone Mountain State Park (K-2754)
Monday was another stunning weather day.
I decided I wanted to finally make a pilgrimage to an ATNO (All Time New One) POTA site I’d been eyeing for a few months: Mitchell River Game Land.
Because propagation was fickle and this site was a good 3 hour round trip from where I was staying with family, I planned to use the Mission RGO One and run 40-50 watts or so.
However, when I got to the site, I realized I’d left the RGO One’s power cable at home. Fortunately, I still had my Elecraft KX2, so 10 watts would have to do.
I found a large parking pull-off area surrounded by trees. There was a ton of room to deploy the Emcomm III.
I decided to extend the radiator in a sloping configuration and elevate the 25 foot counterpoise.
The configuration was Identical to the one above , but the balun/center winder and counterpoise were suspended about 4 feet off the ground.
I fired up the KX2Â and started calling CQ on 80 meters. The RBN picked me up and the POTA site auto spotted me. In a couple of minutes, I snagged my first three stations, then I heard no other calls, so moved up to 40 meters where I worked a big pile-up of stations. It felt like a mini-DXpedition at times. I loved it!
I even hopped on the phone portion of the 40 meter band and worked a few stations, getting respectable signal reports despite unstable propagation.
This activation went so well and the weather was so ideal, I decided to fit in another park that was only a 30 minute drive and was new to me: Stone Mountain State Park.
The thirty minute drive was relaxing and reminded me how much I enjoy this portion of the NC foothills leading up to the Blue Ridge Parkway and escarpment.
By the time I reached the park it was 1:30 pm on a Monday and I essentially had the place to myself (even though in my head I was preparing for crowds).
I had my pick of picnic spots so I found the one with the highest branches. One shot with the arborist throw line and I snagged a branch that must have been 45-50 feet high.
I first deployed the Emcomm III by simply running the radiator over a tree branch and laying the counterpoise on the ground–much like I did in the first Emcomm III activation and deployment.
I started calling CQ and worked about 4 stations, then nothing. The bands simply died on me!
After 30 minutes, I reconfigured the Emcomm III into a similar “V” shape I used at Pisgah National Forest with the apex at about 40 ft and the center winder and counterpoise elevated about 3 feet.
After some persistence, I finished off my ten contacts and then packed up–I spent about 70 minutes on the air and needed to grab lunch!
I honestly believe I would have found this activation even more challenging if I didn’t have an antenna that could snag stations on the 80 meter band since it was in the best shape that afternoon.
Again, I was very impressed with how easy it was to reconfigure the Emcomm III.
Tuesday, September 22: Tuttle Educational State Forest (K-2754)
After staying two nights with my parents in the Piedmont of North Carolina, I made my way back home to the mountains Tuesday afternoon. Again, the weather lured me back out to make just one more activation! (Let’s face it: the weather is a bit of an excuse).
One of my favorite parks that’s only a 20 minute detour off my path is Tuttle Educational Forest. It’s never busy there and they have a large picnic area with ideal trees for hanging antennas.
After searching through my main field pack (a Red Oxx C-Ruck), I found a spare power cord that would work with the Mission RGO One transceiver.
I didn’t have a microphone, though. That’s okay: it would be a CW-only activation.
Although I had the park to myself, I didn’t want to take up a large portion of the picnic area by deploying the Emcomm III in a sloping configuration similar to my activation at Mitchell River. I decided, instead, to be space efficient and use the “V” configuration once again with the apex at about 35 feet and the counterpoise on the ground. By doing this, the antenna footprint could almost fit within my picnic table area (although my counterpoise did snake into the woods).
I can’t remember how long I was on the air, but I do remember it was a breeze logging contacts that afternoon. Very enjoyable. I do love the Mission RGO One–the receiver is amazingly quiet, sensitive, selective, and signals simply pop out of the ether. It also sports silky-smooth QSK. Again, although I’m 90-95% a QRPer, it’s nice to push the juice a bit when propagation isn’t kind. The RGO One will push 55 watts.
The Mission RGO One ATU also snags excellent SWR matches across the band with the Emcomm III.
Emcomm III initial impressions
This past week, I gained some serious respect for the Emcomm III.
What impresses me most is its versatility and robust quality.
Don’t get me wrong: it’s not a magic antenna or anything. It’s essentially a random wire antenna.
What makes it such a fabulous field antenna, though, is its configurability. That and its uncompromised military-grade construction.
I shouldn’t have been so concerned about the radiator length as it’s actually pretty easy to accommodate and helps make this an efficient antenna on the low bands. (Look for me activating parks on 160 meters this winter!)
I believe I can deploy the Emcomm III anytime I have a half-decent tree nearby. I believe I could also use my 31′ Jackite fiberglass pole to extend one end or even the middle of the antenna if I wanted to go NVIS, but I would have to be careful to accommodate strain relief since the Emcomm III Portable is made of heavier materials than my EFT Trail-friendly antenna, for example.
I’m not sure I’d ever reach for the Emcomm III for a SOTA activation when I’d need to take a close look at weight and size. But for POTA? It’s brilliant. And, of course, for emergency communications (as the model name implies). The Emcomm III would also be an excellent addition to a radio club’s antenna arsenal.
The Emcomm III, like all Chameleon products, is designed and made in the USA. Since they use military-grade components, you pay a premium.  The Emcomm III is one of their least expensive products at $139 US. Is it worth the price? Absolutely. In fact, I’m thinking about buying a second one to keep in my camper.
Thank you, Chameleon Antenna, for sending me the Emcomm III Portable for a proper field evaluation. I’d also like to thank Chameleon Antenna for agreeing to be a sponsor of QRPer.com!Â
I know a number of participants in the Parks On The Air program who use the CHA MPAS antenna system–the MPAS Lite is the “little brother” of that antenna, according to Chameleon.
Although designed with the new Icom IC-705 and other QRP transceivers in mind, the CHA MPAS Lite can handle up to 100 watts in SSB or 50 watts in CW.
They plan to start shipping the antenna in early November 2020 and the price for the system is $340.00. That may sound like a lot of money for an antenna (it is, let’s face it!) but if you speak with pretty much anyone who owns a Chameleon antenna they’ll tell you it’s worth it. The quality is second to none. I’ve been testing their Emcomm III wire antenna recently and it must be one of the most robust portable wire antenna systems I’ve ever evaluated.
Also, all of their products are designed and manufactured in the USA.
We recently added Chameleon Antenna to our list of sponsors here at QRPer.com. I’m very proud to include them because one of my personal missions is to promote mom-and-pop companies that push innovation here in our radio world! It’s humbling that they support us too.
Complete details are provided in the construction manual to build the kit in 15 Steps.
There are 15 individual kits packets provided to assemble the kit step by step.
The si5351 BFO VFO is provided with the kit in working condition. Only The IF frequency has to be set as described in the manual.
The easy bitx kit is an excellent educational kit for new Hams
who are wish to learn how to build a single band transceiver.
And later use it on the air.
The bitx in various kits and individual mods has been build by thousands of hams world wide, so this way easy bitx is a perfect kit for newbies.
The complete kit can be purchased from our website.
Presently we are shipping world wide with DHL Express.
Over at our other radio blog, the SWLing Post, I’ve been publishing reports and videos of the lab599 Discovery TX-500 general coverage QRP transceiver. If you haven’t been following those posts, you might like to check out the following articles in particular:
Many thanks to SWLing Post contributor, Frank (ON6UU), who shares the following guest post which expands upon his previous DB4020 article:
The EA3GCY DB4020 transceiver now has CW mode
by Frank Lagaet (ON6UU)
After telling you all about the DB4020 SSB build I’m here with the CW part of the kit, let’s say this is part 2. At a certain moment Javier let me know the CW interface kit was ready for shipment and some week later it was delivered to my QTH.
Again, a well packed kit arrived in a brown envelope, components and boards well packed in bubblewrap. I found even a board I did not expect which can hold a push button, a switch and the connector for your morse key. Javier thinks of everything it seems!
Unpacking the bubblewrap gave me this result, all components in 2 bags. In the bigger bag another 2 bags with 2 printboards, one for the CW interface, one for the CW filter. Great !! Checking the material bill resulted in all components there, another thumbs up.
I started, of course, immediately building it because I wanted CW in the transceiver as soon as possible. I don’t do much in SSB mode anymore and I already started missing CW on the DB4020, so I started my KX3 to listen to while I was populating the boards. I never thought CW was going to have this impact on me! …. ..
I started building the CW interface, again starting with all small items. I soon saw that the 2 relays which need to be soldered in were ideal to protect all components when the board is upside down, so I soldered them in very quickly. I then soldered in all other components ending with the elco’s.
Next phase was the CW filter. This board is small and came together in a blink of an eye, no problems there, the long legs of the 3 and 4 pin headers went in last.
The following day, I made all wire connections and soldered a 13pin connector, leaving one pin out since I want to have the option to choose the width of the CW signal I’m listening to. By cutting the FL CW + pin and adding an additional switch, I have now 500Hz or 2400Hz. Great option, for very little effort and simple. Another thumbs up here.
Now it was simply a matter of inserting the sub boards in the main board and all should be working. And it did! Hurray! The 500Hz filter works perfectly, filtering away all above or below stations nearby my operating frequency.
This is the result of the soldering work, 2 small boards which need to be inserted in the main board:
The CW interface still needs the 13pin header of which I cut one pin and mounted a switch to have the 2400Hz width.
The IC you see in the middle of the CW interface is the KB2 keyer which gives you several functions like 4 memories and beacon mode. The 4 potmeters are used to set the level on 40 and 20 meters, to set the delay between TX and RX switchover and to set side tone monitor level.  The keyer also provides functions as keyer mode A or B, straight key function and can be set for speeds between 1 and 50WPM.  WPM speed can be set in 2 different ways. Handy!
Here a picture of the CW filter inserted on the main DB4020 board.
The CW interface is inserted at the side of the main board, notice the 2 wires which go to the switch to allow switch-over between 500 and 2400Hz.
(Wiring still needs to be cleaned up in this picture.)
Finally, the result: a good working multimode QRP transceiver with 2 bands. It should be possible to make close to medium range with it as well as DX, even with QRP power.
And while I was building I also made a new key for this radio, it is made out of a relay and cost nearly nothing, looks good doesn’t it ? hihi.
Homebrew key
The key, when in practiced hands (fingers hi), can do 50 WPM without a problem. My friend HA3HK does without blinking an eye at 40WPM with this kind of key and tells me that he can go faster if needed. Me? I’m going it a bit slower.
Battery pack
As this radio is only using little power (0.4A in RX, 1 to 2A in TX depending the power you set it) I thought, let’s make a battery pack for the radio.
The first plan was installing it in the box. I did not do that because the batterypack is also powerful enough to feed my KX2 and other QRP transceivers. Since I can use it with all of them, a loose battery works out better for me.
I started with an old laptop which had a broken screen and some other malfunctions, but still had a good battery, although I needed the battery connector of course. A piece of wood to mount the connector on was my next goal. And since I still have another laptop using the same batteries, I can charge the battery without problems. Simple, but good and it weighs much less than a gel cell battery.
The battery provides me with 12.5V and some 5Ah. Enough to last for hours on RX and for sure good enough to activate 2 SOTA sites in one day.  It doesn’t look great but works great– that is what matters and to test it was more then good. Next will be getting the battery pack in a nice box. Better to re-use stuff than throwing it away I’m thinking.
I need to do something about the cover of the OLED display, there is still some work there to make it look nicer.
Some video can be seen on YouTube :
Finallym I’d like to thank you all for reading my articles about the DB4020. I had big fun soldering, tinkering with the box, making the key, and batteryholder/batterypack. My Hungarian friend HA3HK told me it looks a bit like a spy radio. …. ..
I also include one more time the link where you’ll find this kit :
Thank you so much, Frank. No doubt, you had a lot of fun putting this excellent little kit together.
Implementing a filter switch was a fantastic idea and, obviously, not terribly difficult to do.
Based on the videos, the DB4020 has a low noise floor and very good receiver characteristics. I’m impressed that the CW portion of the radios has so many features as well, such as a memory keyer and beacon mode.
I also love how you reused that 5Ah laptop battery! I think that could almost give you a full day of SOTA activations at those consumption levels!
Thanks again for sharing this with us, Frank! We look forward to your future articles!
The following article first appeared on our sister site, the SWLing Post:
Many thanks to SWLing Post contributor, Frank (ON6UU), who shares the following guest post:
Building EA3GCY’s DB4020 QRP Transceiver kit
by Frank Lagaet (ON6UU)
In May, I discovered via a newsletter that a new kit was available from Javier EA3GCY in Spain. I was immediately sold as this was a kit from my favourite kit producer and it has 2 bands–it will also be able to do CW and there also will be a CW filter.
After building 2 MFT’s from Javier which work without problems, I needed to have the DB4020. The MFT’s are for 20 and 40 mtrs and do DSB (double side band). I did put them in a not-so-graceful box but they do what they are intended for which is QRP phone (SSB).  They came together without problems so I expected the same for the DB4020–I knew for sure when I saw the board: all through-hole components (except for some capacitors which are factory soldered) and a lot of space on the board.  The board has been silk-screened with clear indications on where all components have to come and the manual has very clear instructions where each component has to be soldered with referral to a quadrant. The manual provides a 252 quadrant page so it is a piece of cake to find where each piece goes.
What do you get?
Javier provides you with all components which need to be installed on the board and, of course, the kit board. The components come in small marked plastic bags and all is well-wrapped up in bubble wrap. The board is wrapped separately and that is put together with the component wrap which is then again wrapped up in bubble plastic. All goes into an envelope. Very well packed I must say.
Here’s a picture of the bags with components:
The silk-screened board:
I started with the resistors since that’s the easiest way. After that, I did the capacitors. I like to solder in all flat components first, so next were the diodes and IC sockets followed by the elco’s. The transistors were next together with all relays. As you solder in the transistors one also has to mount the cooling heatsinks, these cooling sinks are high and are ideal to protect the coils one has to make, they also protect the polystyrene caps (which I always find vulnerable) when the board is upside down.
Many kit builders are afraid of winding the toroids in kits–don’t be! It is easy. Just take your time and follow the instructions given by Javier in the construction manual. In this kit the builder has to wind 8 toroids: 6 are a single wire which goes through the toroid body, 1 is a toroid with 2 different windings, and 1 has a twisted pair which goes through the final toroid. Be sure to measure the wire you need per toroid as instructed in the manual. Javier gives some spare, so you can be sure. You will also see that on next picture where the legs of the toroids have not been trimmed yet. Once done I still had some centimetres of wire leftover.
Picture of the toroids ready to be soldered in:
Finally all other parts and pin headers went in, jumpers were immediately put on where needed.
As I’m using a military-grade plastic box, I have to break-out some components like the display, tuning encoder, volume and rx control from the board. I also have put an on/off switch on the box and already have the CW KEY connector ready installed. I also installed a loudspeaker in the box. The SI5351 board and the Ardiuno Nano are the final components which go into the board after installing all wires.
Picture of the board:
I intend to attach a CW paddle to the box made out of a relay. A HWEF tuner (from EA3GCY) which I was planning to incorporate in the box is I think a bit overkill. That HWEF tuner is already in a nice little box and would be a pity to dismantle, also I’m running out of space in the box… Maybe I can fit in a 9-1unun which would then give me good results on both bands…?
Maybe I will install a battery pack in the same box.
The box with board installed:
The box completed front side:
Mind you, it still needs some additional switches for the CW part of the transceiver.
73
Frank (ON6UU)
Video
Brilliant, Frank! I really appreciate the video as well–sounds like the kit produces smooth audio and should serve you well. No doubt, that military box enclosure will survive even the roughest field conditions!
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Many thanks to Alex (W3AVP) who shares this photos of his homemade cootie/sideswiper originally posted on the POTA Faxcebook page. Alex notes:
