Tag Archives: QRP Kits

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!

QRPGuys new DSB Digital Transceiver kit

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

QRPGuys has just introduced a new Multiband DSB Digital Transceiver for FT8.

At $40 it introduces a new price point for such Rigs as it includes band modules for 40/30/20 Meters! For those wanting to experiment with different Bands extra bare boards are available for sale.

The rig as it comes is crystal controlled for FT8 but fear not the main board includes connections for an external VFO. As an example one could use one of the very popular Si5351 VFO Kits and be able to QSY to operate the different modes available to the Amateur Community today.

Let the fun begin 🙂

Pete WB9FLW

Thanks so much for the tip, Pete! What a great little project!

Click here to check out the DSB Digital Transceiver at QRPguys.

QRP Labs Announces The QSX Transceiver

The QSX Transceiver

Many thanks to Pete Eaton (WB9FLW) who writes:

QRP Labs has just announced the QSX an All-Band All-Mode Transceiver Kit that should be available later this year. The Target price for the 10 Band Model is $150, also available will be a 40 Meter version for $75.00.

Details from QRP Labs:

QSX (QRP Labs SSB Xcvr) is a 40m SSB transceiver with 10-band (160m-10m) and enclosure options. The kit inherits all the functionality of the famous QCX single-band CW transceiver kit but adds SSB, AM, FM, PSK31 and RTTY. This will be the lowest cost all-HF radio available but also high performance and packed with features. These are the planned features of QSX:

  • Software Defined Radio (SDR) technology with standalone Digital Signal Processing (DSP), no PC required
  • Very high performance 24-bit Analog to Digital Converter (ADC) and 24-bit Digital to Analog Converter (DAC)
  • 40m (single band) or 160-10m (10-band, including 60m) versions available
  • Modes: SSB, CW, AM, FM, PSK31, RTTY, WSPR beacon
  • Power output: 10W from 13.8V supply (power output is adjustable by the firmware)
  • Single power supply needed, 12V to 14V
  • USB host interface and connector, for USB keyboard to allow PC-less operation on PSK31 and RTTY
  • USB device interface and connector, for PC CAT Control
  • QSX can appear to a PC as a high performance 24-bit USB sound card and radio – for digital modes from a PC e.g. FT8, either demodulated or as I-Q for PC SDR programs
  • Built-in CW IAMBIC keyer (or straight keying also possible) with raised-cosine key-envelope shaping
  • DSP features (selectable sharp filters, AGC, Speech Compression, Noise Reduction etc.)
  • Dual microphone inputs (mobile phone headset with VOX, or RJ45 connector for Kenwood/Yaesu mics)
  • Dual VFO (A/B/Split), frequency and message memories
  • Through-hole assembly only
  • Built-in test equipment features for alignment, debugging and general purpose use
  • Detailed assembly manual
  • Macro facility for user defined sequences of operations, or redefinition of controls
  • Front panel: 16 x 2 LCD (yellow/green backlight), 2 rotary encoders, 4 buttons, mic/earphones socket
  • Soft-power on/off switch, the radio saves its state automatically on switch off, so that it starts up in the same state next time
  • Free firmware updates for life, very simple firmware update procedure via a USB memory stic

QSX is still in development! The above list is subject to change. The following is a FAQ with information about QSX.

More Info on QRP Labs Web Page:

https://www.qrp-labs.com/qsx.html

Check out the following video from YOTA 2018:

Click here to view on YouTube.

Fantastic! Many thanks for sharing this, Pete! This looks like a brilliant little kit for any skill level of patient kit builder.

The uBITX Transceiver: Pricing and more details

Many thanks to Pete Eaton (WB9FLW) who shares pricing and additional information about the uBITX general coverage QRP transceiver:

Here are the details, if purchased before Christmas $109 delivered!

http://www.hfsignals.com/

From uBITX creator, Ashhar Farhan:

1. The ubitx is now available for sale, for $109 dollars (includes the shipping), but only until Christmas. *After Christmas, the price will increase to $129 dollars. for this initial batch, a few ham volunteers and I pitched in to sort the crystals, test the coils, tune-up and box these initial kits, we won’t be able to do that any more. we will have to hire more people (which is not a bad thing) and get them to do it.

2. The ubitx is on sale at hfsignals.com, not hfsigs.com. it is easier to remember. we will soon point hfsigs.com to the new website as well. The new site is in wordpress, that means that we can have volunteers writing and updating it rather than waiting for me to hand code the content in html and vi editor.

3. We need help with proof reading the web content.* If you find any typos, please mail me on farhanbox@gmail.com address (not the bitx20 list),

These apart, the early buyers must be aware that they are beta users of sorts, the firmware will sure get updated. i hope there won’t be any revisions of the PCB.

Pete adds:

Just as an aside the original price of the Heathkit HW-8 was $139.95 (in 1970 dollars) and it became a QRP Classic. The uBITX may become  one as well and like the HW-8 there will be (and already are) all sorts of mods/additions one will be able to do. The uBITX is 10 dollars cheaper (after 12/25) works 80-10 M, does SSB in addition to CW, and is a Superhet to boot!

Farhan your hit this one out of the Ballpark!

Very cool, Pete!  I am very tempted to purchase the uBITX transceiver before Christmas and have it delivered via DHL service.  The only thing holding me back is simply the amount of projects I have on my table at the moment! $109 is an incredibly low price for a full-fledged QRP transceiver!

I’m absolutely amazed that it is also has a general coverage receiver.  Perhaps the uBITX could serve the SWL as well as the ham radio operator?  I suppose we shall soon find out!

Click here to read our other posts regarding the uBITX transceiver.

Click here to order the uBITX transceiver kit.

Please comment if you plan to or have purchased the uBITX. We’d love your feedback!

Ten-Tec holiday specials include QRP kits

Ten-Tec is discounting their 1380 and 1330 QRP kits for the holiday season. They’ve also extended their discount on the R4030 QRP tranceiver (details below).

(Source: Ten-Tec)

The 1380 and 1330 QRP transceiver kits, which are regularly priced at $124.00, are $99.00 through Christmas.  These are great QRP kits and many are used on the air daily and in QRP contests.   It is great fun to work 80 meter QRP in the winter months,  so order yours today.  http://www.tentec.com/products/80-Meter-QRP-Transceiver-Kit.html

The R4030 transceiver is still at $188.00 from their list of $249.00 and this price will continue through Christmas.  This is a great trail friendly QRP transceiver with lots of features like an LCD frequency readout display, cw memories and much more.  This is a great price for a full-featured QRP rig.  Read more about the R4030 at http://www.tentec.com/products/Sale-Price!-Two-Band-CW-QRP-Transceiver-%252d-40-%252d-30-Meters.html

Hamvention Photos: Hendricks QRP Kits

Doug Hendricks holding a Ft. Tuthill transceiver

Another very active table at the Dayton Hamvention and Four Days in May is that of Hendricks QRP Kits.

Doug Hendricks (pictured right) and his team produce some amazing, affordable QRP kits that fill many a niche in the shack. Below, I have photos of a small selection of their offerings at the Hamvention.  Note that all of these kits are available on the Hendricks QRP Kits website.

Many of Hendrick’s kits are suitable for beginners. If you’re in doubt about your kit building skills, simply contact the folks at Hendricks and they’ll help guide you to the right kit.