Tag Archives: QRP Kits

The QRP Labs QCX-mini CW Transceiver

by Scott (KN3A)

I have been a fan of QRP operating since I got licensed in 1983. The sticker in the picture is a joke a good friend who is not into CW or QRP, so I include it in my field pictures.

My interest in ham radio had reached a point I was getting away from the hobby. In 2020, I learned about Parks on the Air (POTA) and Summits on the Air (SOTA). I got hooked on activating parks and summits, and now I mostly do QRP CW, much like Thomas Witherspoon, K4SWL does.

Over the past year, I’ve been refining my antennas and radios in the field. I have different radios and antennas for different reasons, and to just mix it up a bit. Occasionally, I will take my IC-7100 or IC-7300 out into the field with my Bioenno 20aH battery, if I’m not planning to hike or go far from the parking lot, or if the bands are just not cooperating.

Back in November 2020 I had my left knee replaced so I had lots of down time and made an important purchase for field activities – an IC-705. It is fantastic and does everything I want it to do without a lot of wires. I’ve also owned and sold within the past 18 months a Yaesu FT-891 (which I sold when I got the IC-705) and had both the Xiegu G90 and X5105.  I would expect one day to get another FT-891 as it has amazing filtering and pulls in weak CW signals better than any radio I’ve owned. The G90 and X5105 are okay, however I was not impressed with the G90 from the start for out in the field. There were just too many wires in order to set up and use with my portable laptop computer if I was taking that along.

The X5105, which I had high expectations for, disappointed me in the fact that storing and using CW memory keying is not user friendly. The nice thing about that radio is, no microphone, no problem, I had some success using the 5105 and got great audio reports.

I’ve been looking ahead to my projected retirement and hopes of through hiking the Appalachian Trail in 2026. Although the IC-705 is an excellent field radio, all mode, VHF/UHF/D-Star/HF/6 meters, I already know for a 7 month hike from Georgia to Maine, it will just be too bulky in my backpack. I have heard really good things about the QCX-mini, however I’m an appliance operator and not good with kit building and soldering.

I saw there are options to purchase an assembled QCX-mini, so I decided to check out a 40 meter radio. It took about 2-1/2 weeks before it arrived at my QTH on Saturday afternoon. I hooked it up to one of my HF antennas in my yard  used for my IC-7300 that was resonant on 40 meters. I had to use my Heil headset in order to hear the audio, plugged into the 3.5 mm jack. I used my CWMorse paddle and tuned around the band. I called CQ several times before finally I heard WA0USA in Palm Beach, FL calling CQ. I called him and got a 579 report and he was a solid 599. We chatted for about 10 minutes, and he was running a kW while I was using 5 watts. It felt good to know that I was being heard.

Sunday morning I had time to go activate a local park (K-1418) before some afternoon commitments. I had also recently purchased a link dipole for 20/30/40 meters off eBay from N9SAB. I had tested this antenna out a couple of times last week, so I wanted to pair it with the QCX-mini. I went with little expectations about the little mini, so I also packed my IC 705 just in case I needed it to complete my 10 contacts to have a successful activation. To my surprise, I spotted myself on the POTA page, and in 45 minutes I had a total of 26 QSOs in my HAMRS log! It was amazing and I think I found the perfect combination for true lightweight, portable operations.

I was so impressed with this activation that last night I ordered the 20 meter QCX-mini! These can be ordered from qrp-labs.com and they have a lot of other kits available as well. The kit itself is $55, and I opted to have it assembled ($45) and purchased the enclosure ($20).

This little radio is very user-friendly. I was able to easily access the menus, customize it to my liking, including the paddle, preset frequencies, several stored CW memories, and was on the air calling CQ Saturday evening without seeking out the instructions.

I had mentioned previously about my disappointment with the Xiegu X5105 and not being able to easily store and recall memories. Not a problem at all with this little radio. I enabled the decoder feature just to test it out, and it decodes better than the G90 or X5105, including very weak signals. The size is a fraction of the size of the X5105 and total weight for everything, including the Bioenno 12v 3aH battery is less than 2 pounds and it all stores very nice.

These quick videos were taken this evening before storms hit; that’s why you will hear lawnmowers in the background. I wanted to first show a demo of the receive decoder and how well it decodes even weaker signals:

My biggest complaint about the X5105 was how the memory was next to impossible to use. I do a quick demo how to access a stored message and send it over the air. I also have it set to repeat every 6 seconds:

I did make a couple of changes to the radio setup. I did not like having to use the headset, so I went on Amazon and purchased a mini portable 3 watt mobile phone speaker line-in speaker with 3.5mm audio interface (affiliate link). That cost under $15 and works extremely well. It has a built in charger that plugs into a micro-USB to charge the battery when not in use. I also have a cell phone holder that fits perfectly on my Neewer stand I purchased several months ago for my IC 705, and it sits nice and firm on the table. I may not take that to the field if I’m doing a lot of hiking.

Here are some other details about the QCX-mini from their website:

The Optional enclosure is black anodized extruded aluminium, very sturdy and elegant. The enclosure size is 95 x 63 x 25mm without protrusions. The top and side panels are drilled and cut to match the QCX-mini with laser-etched lettering. The enclosure includes four self-adhesive feet.

Special portable-friendly features:

  • Small size: 95 x 63 x 25mm enclosure (plus protusions)
  • Low current consumption (for example 58mA receive current, with 12V supply and display backlight off)
  • Low weight, 202 grams
  • Sturdy extruded aluminium enclousre
  • All-metal BNC short connector, bolted to enclosure

List of features: 

  • Easy to build, two-board design, board with main circuit and connectors, display panel board with LCD; all-controls board-mounted on a press-out sub-board. No wiring, all controls and connectors are board-mounted
  • Professional quality double-sided, through-hole plated, silk-screen printed PCBs
  • Choice of single band, 80, 60, 40, 30, 20 or 17m
  • Approximately 3-5W CW output (depending on supply voltage)
  • 7-14V recommended supply voltage
  • Class E power amplifier, transistors run cool…
  • 7-element Low Pass Filter ensures regulatory compliance
  • CW envelope shaping to remove key clicks
  • High performance receiver with at least 50dB of unwanted sideband cancellation
  • 200Hz CW filter with no ringing
  • Si5351A Synthesized VFO with rotary encoder tuning
  • 16 x 2 yellow/green LCD screen
  • Iambic keyer or straight key option included in the firmware
  • Simple Digital Signal Processing assisted CW decoder, displayed real-time on-screen
  • On-screen S-meter
  • On-screen real time clock (not battery backed up)
  • Full or semi QSK operation using fast solid-state transmit/receive switching
  • Frequency presets, VFO A/B Split operation, RIT, configurable CW Offset
  • Configurable sidetone frequency and volume
  • Connectors: 2.1mm power barrel connector, 3.5mm keyer jack, 3.5mm stereo earphone jack, 3.5mm stereo jack for PTT, 3.5mm stereo jack for CAT control,  BNC RF output
  • Built-in test signal generator and alignment tools to complete simple set-up adjustments
  • Built-in test equipment: voltmeter, RF power meter, frequency counter, signal generator
  • Beacon mode, supporting automatic CW, FSKCW or WSPR operation
  • GPS interface for reference frequency calibration and time-keeping (for WSPR beacon)
  • CAT control interface
  • Optional 50W PA kit
  • Optional aluminium extruded cut/drilled/laser-etched black anodized enclosure

Just a quick note on the link dipole. It is well made and I had a 1:1 SWR on the CW part of the band, which is perfect. I did put the IC 705 to work when I attempted to work a couple of SSB stations on POTA, and at 7.235 the SWR was only about 1.3:1, so minimal loss. Check out the N9SAB antennas on his eBay site. His shipping is very quick. I took a picture of the balun with the included choke in the package I purchased, and the second picture is the link between the 20 and 40 meters. It works great.

I mentioned my goal about hiking the Appalachian Trail in 2026. I’m sure there will be other multi band mini size radios available by then and I’m hopeful QCX will have one in 5 years for me to use. My goal is to activate summits along the way while taking breaks from the hiking, or at night before calling it an evening. Since I’ll be on the A.T. I’ll also have lots of opportunity to activate POTA as well. Most thru hikers are not hams and they are always concerned about no cell phone coverage. I won’t have that issue and I’m confident I’ll be able to be in touch with other hams throughout the journey.

Thank you once again Tom for allowing me to post on QRPer. I think I finally have a QRP radio that you have not tested or purchased yet. I hope your readers find this short article useful.

73

Scott – KN3A


Scott Lithgow (KN3A) is a regular contributor on QRPer.com. Click here to check out his previous posts.

WA3RNC’s TR-25 and upcoming TR-45L transceiver kits

Many thanks to a number of QRPer readers who note that WA3RNC has recently introduced the TR-25 CW Transceiver Kit and announced the upcoming TR-45L QRP Transceiver Kit.

Here’s the info about the TR-25 from the WA3RNC website:

Here is a compact but powerful 2-band CW transceiver kit that uses no tiny pushbuttons, and without those seemingly endless and hard-to-remember back menus. There is a knob or a switch for every function!

    • Size 5 ½ X 3 ¼ X 1 ½ less protrusions, weight 10.6 Oz
    • Full band coverage of 40 and 20 meters
    • About 10 watts output with a 14 volt power supply
    • 5 Watts minimum output with a 10 volt supply
    • 4 Watts output with an 9 volt supply
    • Optimized for operation from 3 series-connected 18650 Lithium cells
    • RIT tunes + and – 5KHz
    • Blue OLED display reads frequency to 10 Hz and RIT offset
    • Built in Iambic keyer is adjustable 5 to 35 WPM with front panel control
    • Separate jacks for straight key and paddles; Always ready for SKCC contacts
    • Operates on 9 to 14 volts, < 90ma receive, about 1 Amp Xmitt at 10 volts
    • Selectable tuning resolution steps of 10, 100, and 1000Hz
    • Low battery indicator with internal adjustment 9 to 12 volts
    • Front panel adjustable RF gain control
    • Front panel TX power control; Adjustable from 0 to 10 watts (@14V)
    • Rugged TO-220 FET RF amp can deliver 5 Watts key down for 5 minutes
    • Signal quality blue LED, RIT warning orange LED, Low battery red LED
    • More than enough audio to fill any room with an external speaker
    • Excellent receiver sensitivity with MDS of -132dBm (0.06 microvolt)
    • Very effective receive AGC prevents ear damage with strong signals
    • Transmitter harmonics and spurs -58dB, meets FCC specs
    • CW sidetone is the actual transmitter signal as heard by receiver
    • Match the received signal tone to the sidetone for perfect zero beating
    • Sharp IF filter; Better than 300 Hz at the -6dB point, plus 700 Hz audio filter
    • Over 200 machine placed SMT parts, and about 55 user installed parts
    • All critical circuits are factory pre-aligned and calibrated
    • No endless “back menus”; There is a control or switch for every function
    • Options include pre-wound toroid coils, precision optical tuning encoder, and complete factory assembly

Price is $250 or you can add pre-wound toroids for $18, a precision optical encoder for $30, or for $310 you can purchase this kit fully assembled and tested. Click here to check it out.

Here’s the info about the TR-45L from the WA3RNC website:

    • TR-45L is a 4-band 5-watt CW transceiver covering the 80-75, 40, 30, and 20 meter bands.
    • Full band coverage is provided, with the transmitter optimized for the CW band portions.
    • The receiver is provided with both narrow and wide band IF filters, and CW and SSB detectors.
    • An illuminated front panel meter shows “S” units on receive, and power output (forward or reverse) while transmitting. The meter also will display the battery state of charge.

    • A “High SWR” warning indicator will illuminate if the antenna SWR exceeds about 2:1.
    • The transmitter power output is adjustable from less than ½ watt to 5 watts with a front panel control.
    • RIT is provided to adjust the receive frequency up to + or – 5 KHz from the transmit frequency.
    • Two VFOs for each band are provided with recallable memories.
    • A built-in keyer is adjustable from about 5 wpm to 35 wpm with a front panel speed control.
    • Separate straight key and keyer paddle inputs are provided on the front panel.
    • A front panel adjustable sharp notch filter is provided to null out interference.
    • A front panel receiver RF gain control is provided.
    • Operates from a 12 volt nominal power source requiring up to 1.3 amperes on transmit, and about 130 ma on receive. A front panel power on – off switch is provided.
    • Tuning speed is easily settable from 1 Hz to 1 KHz per step.
    • A selectable dial lock is available to prevent inadvertent frequency changes.
    • There is a knob or switch for every function – no confusing back menus!
    • Size 8-1/2” wide, 5” high, 3” deep Weight about 2.8 lb with Internal Batteries

Beta testing is continuing…73 de WA3RNC

 No pricing or availability has been noted yet.

I life the look of both of these kits. I love the fact that you can buy pre-wound toroids as this is often one of the more complicated parts when building radios. Also, I’m pleased to see that all SMD components are pre-installed and that all critical circuits are factory pre-aligned and calibrated. That will make this kit accessible to a much larger kit building audience.

Click here to check out the WA3RNC kits!

Frank builds the EGV+ Three Band QRP CW Transceiver Kit

Many thanks to Frank Lagaet (ON6UU) for sharing the following guest post:


The EGV+ Three Band Transceiver Kit

by Frank Lagaet (ON6UU)

Another EA3GCY kit has seen daylight.  The EGV+ is ready for you all.

It was beginning 2021 I got word a new kit from EA3GCY was ready and distribution could start.  After a successful build of the DB4020 I did not need much time to decide to buy this kit,  a week later the kit arrived at my QTH.  As weather was good I did not start immediately building but then winter kicked in, with snowfall and frost,  perfect time for some quality time and building the kit.

What do you get ? 

The kit has a general coverage receiver from 6 to 16MHz,  it has a keyer built in,  has RIT without limit,  requires only 0.25A on RX and smaller than 2A on TX.  Dimensions are 18x14cm and weight is 0.3Kg.   It is CW only, able to produce 8W on 40 and some 5-6 on 30 and 20.  The kit has an AB class amplifier.   Spurious is below -50DBc.  The receiver is a heterodyne type balanced mixer,  sensitivity is 0.2µV minimum and the CW filter is some 700Hz wide,  the AGC is on audio.   Furthermore the transceiver is equipped with both output for loudspeaker as for a headset or earbuds.

The kit arrived in a brown envelope and in that envelope I found a well-packed packet of plastic bags and the printed board well packed in bubble wrap.  Around that another layer of bubblewrap.  Safe!!

All plastic bags were checked,  all needed stuff was there, super,  well done Javier.

All components were installed in about 10 hours “relax max style”,  if you have built some kits already you can easily do this one,  all elements are far enough out of each other,  the board is not overcrowded at all.  Some attention is needed when soldering the IC’s and display but even that is a piece of cake.   Be careful when installing the SI5351 module.

Winding the toroids,  just follow what is in the manual,  it is not that hard to do,  I don’t understand what many find so difficult.  Just take your time and don’t rush into it.

I got the transceiver up and running quite quick. I didn’t install a speaker in the cabinet but decided to go for a transceiver where no speaker is in. If I want to use it on SOTA or GMA I don’t need the extra weight and can take earbuds with me.  So I installed the speaker connector on the board.

I made connections towards the CW key and CMD push button with jumper cables which fit exactly on the headers Javier supplies,  a little glue to keep them in place is also added afterward.  For easy operation I mounted the CW key connector and CMD pushbutton on the front of the transceiver.

Do to be able to withstand high power nearby stations,  I mounted the EGV+ in a homemade box which is made of printboard.  The box should be a Faraday cage to keep all QRM out.  If you buy a box, buy one in metal.  I added a laminated front and back which make the transceiver look kinda cool.   Now you can also buy a box from qrphamradiokits.

Alignment

The alignment is done on 40 meters:  crank up the volume and start turning the 2 coils (L1 and L2)to maximum volume.  Be careful to handle these with caution and don’t use metallic screwdrivers.  Connect an antenna after you’ve done that and do the alignment of the coils again for maximum volume.  Find a station on 40 and redo the alignment once more.  You should already have good results now.

P1 Set sidetone level to your liking.

P2 Set the hangtime of the relay after you’ve been on air–fast fingers will need a quick release. Set this to your liking.

P3 Connect a power meter between a dummy load and the transceiver,  set power on 40 to some 8 Watts.   Measure on 30 and 20 meters,  you should find some 6-7W there.  Don’t set the power to full if you want a long life for the final in the transceiver.  Mine is set for 6W on 20,  resulting in some 7.5W on 30 and some 8.4W on 40.  I think I will reduce even more.

P4 Set to max,  it is the RX-attenuator.

P5 Don’t pay too much attention to the signal meter,  mine is set at 6/8 of the potmeter’s range.  It is only an indication.  If you don’t want the S-meter then you can do a start-up sequence with the tuning knob.

These are in fact the alignments you need to do inside the transceiver.  You should also check Xtal calibration and BFO,  these are settings which you need to do in the set-up.  Don’t forget to write all down when you have maximised these settings. If you do a reset, all these values are erased too so be carefull.

The complete CW 3 bander

Well,  you get a 3 band transceiver which you build yourself,  it has RIT and XIT,  has 4 memories on the KB-2 keyer,  speed of CW can be set between 0 and 50WPM and you can set the KB-2 as a beacon which can be handy too.   The EGV+ provides you with 3 bands which are almost for certain insurance for QSOs when going on SOTA,  GMA or POTA.

You may have noticed some resemblance with the DB4020. You are right as some parts are the same on the board.   The designer worked on the same platform to make two completely different transceivers.  The result is twice the fun for kit builders.

I made a box myself since, at the time of ordering, there were no boxes available,  here’s the result.

The naked printboard transceiver.

After adding a laminated front to the trx,  it looks now like this.  You can see it is not made professionally but I like it.

The paper which is between the plastic was first cut out for the display before placing it in the plastics so giving an extra protection to the display.

I have also made a retractable stand for it,  when folded back it is next to the bottom of the transceiver,  when folded out the stand is under the front of the transceiver,  the retractable stand is also made out of printboard.

It’s an easy-to-make stand–take some old printboard and solder it together.   The pictures explain it all, I think.

Meanwhile, I already made a lot of QSOs with this small (16 X 20 X 6 cm) QRP transceiver.   The power out is better than expected and even reduced so all bands are within QRP regulations.

Finally, I’d like to say that I’m not sponsored to make this kit,  I don’t have any ties with the kit producer, nor do I gain money with building it.   If people would like to have this QRP kit built for them I’m willing to help out in populating the board and aligning it.  A ready made box is available with qrphamradiokits.   This also stands for the DB4020 which I made earlier.

The kit comes for 125€ without shipping costs.  Many European countries will have no shipping costs at all.  The enclosure comes for 50€ all included. This means you have a complete 3 band radio for about 200€.  In my eyes, this is a pretty good deal.

Info about the kit can be found here :   Home – Página web de ea3gcy (qrphamradiokits.com)

And here : EGV+ Three band CW – Página web de ea3gcy (qrphamradiokits.com)

60 Meter “Woodpecker” QRPp Transceiver Kit From Breadboard Radio

I’ve just received the following announcement from Breadboard Radio. Looks like a fun build and quite useful QRP radio for the 60 meter band!


60 METER “Woodpecker” QRPp Transceiver Kit From Breadboard Radio

Breadboard Radio has just released the “Woodpecker” a 60 meter low power CW transceiver for the 60 meter band. The Woodpecker features a crystal controlled transmitter with a 500 milliwatt output on 5332 kilohertz, sometimes referred to as channel 1. The transmitter provides sidetone, receiver muting and QSK with delay.
The Woodpecker’s direct conversion receiver has an adjustable bandpass filter, attenuator and an audio amplifier suitable for headphone level output plus a selectable low / high filter which helps with band noise and static crashes.

The designer, W4FSV has made multiple contacts using a 160 meter inverted L antenna including many from 500 to 1000 miles. The kit is complete with all parts including a cabinet and attractive front panel plastic decal. A two channel 40 meter version will be available soon.

More information is available at www.breadboardradio.com

The introductory price is $49.95 US.

Click here to read the full PDF manual (note this is a large file).

Guest Post: Steve builds a DC30B QRP Transceiver

DC30B QRP Transceiver ProjectMany thanks to Steve (KZ4TN) who shares the following guest post:


DC30B QRP Transceiver Project

by Steve Allen, KZ4TN

I wanted to build a lightweight backpackable transceiver I could take hiking and camping. I chose the 30 meter band as it is specific to CW and the digital modes. I am also in the process of building Dave Benson’s (K1SWL) Phaser Digital Mode QRP Transceiver kit for the 30 meter band. Also, a 30 meter antenna is a bit smaller than one for 40 meters and the band is open most anytime of the day.

I sourced the DC30B transceiver kit, designed by Steve Weber KD1JV, from Pacific Antennas, http://www.qrpkits.com. It appears that they are now (10-11-20) only offering the kit for the 40 meter band. The following information can be used for the assembly of most any kit that lacks an enclosure.

Lately I have been finding extruded aluminum enclosures on Amazon.com and eBay.com. They come in many sizes and configurations. I like to use the versions with the split case which allows you to access the internal enclosure with the front and rear panels attached to the lower half of the enclosure. Most of these enclosures have a slot cut into the sides that allow a PCB to slide into the slots keeping it above the bottom of the enclosure without having to use standoffs. The one requirement for assembly is that the PCB needs to be attached to either the front or rear panel to hold it in place.

DC30B QRP Transceiver Project

As the enclosure is anodized, I didn’t want to rely on the enclosure for common ground. I used a piece of copper clad board that I cut to fit the slot width of the enclosure and attached it to the back panel. I was then able to mount the transceiver PCB to the copper clad board with standoffs. This basic platform of the enclosure with the copper clad PCB provides a good foundation for any number of projects. All you have to do is mount the wired PCB on the board, install the components on the front and rear panel, then wire it up.

DC30B QRP Transceiver Project

I wanted to have the choice of a few frequencies to operate on so I searched eBay for 30 meter crystals and found a source for 4 different popular frequencies. I installed a rotary switch on the front panel and added a small auxiliary PCB with two, 4 pin machined IC sockets. This allowed me to plug the crystals into the sockets. I wired the bottom of the socket PCB first using wire pairs stripped from computer ribbon cable leaving extra length. I marked the wires with dots to indicate which sockets each wire pair went to so I could solder them onto the rotary switch in the correct order. It was tight but I always work with optical magnification so I can see exactly what I’m doing. I have used this crystal switching method in the past with good success.

DC30B QRP Transceiver Project

DC30B QRP Transceiver ProjectThe rest of the assembly was straight forward. I find that most kits are well designed and documented, and if you take your time and follow the directions carefully all should go well. The two most common speed bumps seem to be soldering in the wrong component or bad soldering technique. I double check all component values and placements prior to soldering, and I always use optical magnification while working. I inspect each solder joint and look for good flow through in the plated through holes, and make sure there are no solder bridges.

DC30B QRP Transceiver Project

DC30B QRP Transceiver ProjectThe finished product. I bought a Dymo label maker and it works very well for projects like this. I love using these enclosures and they are a leap forward from the old folded aluminum clam shells I used in the past. I could stand on this without causing any damage. Power out is 1-3 watts depending on the DC power in. The receiver is sensitive and the ability to choose from four frequencies is a real plus.

73 de KZ4TN

Steve Allen
Elizabethton, TN


Wow, Steve! What a top-shelf job on this build! I’ll have to look for those aluminum enclosures as well. Beautiful little rig you’ve made there and I think it’s fantastic you’ve a few crystal frequency options! Thank you for sharing!

An Introduction to the uSDX transceiver kit

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.

Another development track by Manuel Klaerig DL2MAN uses SMT components in a stacked board layout and has a relay switched band pass board https://groups.io/g/ucx/message/1596  and  https://groups.io/g/ucx/files/DL2MAN uSDX-Sandwich Files. A new revision has been released that uses serial resonance class E amp design and easier to obtain relays, https://groups.io/g/ucx/files/DL2MAN uSDX-Sandwich Files with new Serial Resonance Class E Multiband Circuit .

Other development streams include one by Kees Talen K5BCQ https://groups.io/g/ucx/files/K5BCQ uSDX Board Schematics and Jean-Marie T’Jaeckx ON7EN https://groups.io/g/ucx/files/QCXV4.zip.

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/.

I also designed and 3D printed a case for the transceiver and a small box to carry band boards. Info at https://www.thingiverse.com/thing:4582865 and at https://www.thingiverse.com/thing:4587868 and also in the files section https://groups.io/g/ucx/files/3D printed case for Barb WB2CBA V1.02.

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.

http://qrp-labs.com/qcxmini.html 

More information at https://groups.io/g/ucx/topics and don’t forget the WIKI https://groups.io/g/ucx/wiki.

73

Bob,  KD8CGH


Many thanks again, Bob, for sharing this excellent uSDX introduction. Thanks again for the tip, Pete!

Pete also notes that there is a very active uSDX experimenters discussion group on Groups.io with over 100 members: https://groups.io/g/ucx

Adding CW mode to the EA3GCY DB4020 Dual-band 40 and 20M QRP Transceiver Kit (Part 2)

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 :

https://www.qrphamradiokits.com/

73 TU ee

Frank

ON6UU


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!

Frank builds the EA3GCY DB4020 Dual-band 40 and 20M QRP SSB Transceiver Kit

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!

Click here to check out the DB4020 kit at EA3GCY’s store.

Dave Benson’s new Phaser Digital Mode Transceiver kit

Many thanks to QRPer, Pete (WB9FLW), who writes:

Just in time for Christmas, Dave Benson is back with a great new line of Monoband Digital Mode Transceivers! 40 & 80 Meters is available now 30 & 20 Meter Rigs to follow shortly.

Time for me to contact Santa Claus and update my Christmas Wish List 🙂

These are Single Signal Phasing Rigs not DSB.

Pete WB9FLW,

http://www.midnightdesignsolutions.com/phaser/

http://www.midnightdesignsolutions.com/phaser/Phaser-40%20Instructions%20(Rev%20A).pdf

WOW! Thanks for the tip, Pete! I think I might give Santa a hint! This looks like a fun kit!