Wednesday, October 14, 2026

Kit Building - The Pebble

So I have been busy with family stuff the last 5 or 6 weeks, went to Navarre Beach Florida for a week vacation two weeks before the hurricane hit, among other things. I have not had a successful POTA activation in about six weeks. So I have been enjoying being retired, and staying reasonably healthy these last few months. Today was going to be a good day to go to the parks and setup my station, I had everything ready to go, and it started raining. Here it is the middle of October, we've had no frost yet, no snow yet, and today it was 85 degrees and raining. Supposed to get a lot cooler next week. We'll see. This is Indiana. 

Sometime about mid May I heard about a new radio called The Pebble. This radio is being sold by Mike and Becky, AKA The Ham Radio Duo. This is a single band radio for 20m, designed in collaboration with Barb WB2BCA and Guido PE1NNZ. Barb is the designer of the uSDX radio, he does great work! So I placed my order in May....and I knew there was going to be a waiting list. 

My Pebble kit arrived last Friday! I was tied up with stuff all weekend so I didn't even get a chance to fondle the parts and pieces and dream about all the QSO's I was going to have. Let me tell you a little about this radio, it's been out there a while now so you may already be aware but here goes my impression. 

This is a single band 20m radio, capable of SSB and CW and with the right cables cobbled up, it'll do the FT modes. It can be used with a set of paddles, or a straight key. It puts out a little over 5 watts into my dummy load with a 12v DC power source. It will also run in QRPp mode off a USB-C 5v power feed. It has abuilt in microphone, or you can plug in an external microphone. It has a BUILT IN straight key and can accomodate an external paddle or straight key. There are bandwidth filters you can set for 50, 100, 200, 500, 1800, 2400, and 3000hz. Making the filtering good for CW or SSB. Adjustable tune rates of 1Hz, 10Hz, 100Hz, 500Hz, 1Khz, 10Khz, 100Khz, and 500Khz for quick tuning through the 20m band. Also on the easy to use menu system is RIT, AGC, Noise Reduction, 2 levels of Attenuation, three different S-Meter settings, A CW Decoder, CW Tone adjustment, QSK, Keyer speed, a Practice mode for those learning CW, VOX, and a few more tweaks. My kit is Version 1.0.7, dated June 3, 2026, and I have the v 2.7 PCB. 

The first thing I did was visited the builder website: https://hamradioduo.com/pebblehf-quickstart/ Here the Duo has links to download the assembly manual, and Youtube videos of a building session, plus information on operating The Pebble. All in one place. So I downloaded the assembly manual and put it in a binder so I could read along as I started my build.

This kit is entirely open source as well, so if you are inclined, you can download the source and start working on one from scratch.

I need to explain a couple things...I have not successfully built a kit of any kind in about ten years.  I love building stuff and using it on the air but my eye sight and steadiness of hands has taken a turn for the worse. So I was a little concerned that I was going to solder glob this thing and it would end up in the scrap heap...but it was raining, I was trapped at home, and besides....I had already rounded up all my kit building stuff and had it in one place.  So I decided to go for it, slow and with lots of magnified inspections. 

So here is where I started: 


ALL the surface mount parts are already mounted.  There is HOPE.  

The first parts I had to install were the two toroids.  Yes toroids. I have never been afraid of toroids, but these guys are tiny.  One needed 7 turns of mag wire, the other one got 9 turns. Here they are installed, I took my time stripping the enamel off the wires, you can't do a good enough job on these.


Next came the transistors, all three are the BS170 variety found in so many QRP radios these days. They are close together, side by side. If I had one suggestion, it would be to have these socketed.  The BS170 is a cheap transistor and can be found just about everywhere, but they are easily killed by the builder and operator. 


Next thing to be installed was the Diode. Cathode UP, do not install this backwards. If you do the radio  will no-workie. 


Next I installed the DC power jack, it can only go on one way so I was safe there. 


And then it was time to install the PCB mounted BNC antenna jack.  This jack has four solder points, make sure you get them all and use plenty of solder, this jack will have a heavy antenna attached eventually.


Now we are done putting parts on the back of the PCB, now it's time to attach the LCD screen. The header is 16 pins, on the top, and 16 pins on the bottom.  By now my eyes were getting fatigued, I took a break before starting this section.  My soldering job looks downright amateur...but hey, I ain't getting paid for this. 


When soldering the pins on the bottom of the PCB I accidentally touched the DC power jack housing with the soldering iron.  It's ugly but it's ok. 


Next I added the tuner pot, pushbuttons for the menus, the microphone element, and the little straight key doo hickey. 


Time for the smoke test.  I will admit it did not go well at first.  My display was only showing a row of little black boxes.  The Ham Radio Duo assembly Youtube explained this is caused when the builder slobbed the job of the 32 solder joints to the display.  So I broke out my magnifying glass, and did a close order inspection of my shameful and disgusting solder job and I found two cold solder joints, and two pins I didn't even have soldered.  Did I mention this is the first kit in 10 years?  After I fixed those, I applied power, and quite frankly I would not have been surprised if it burst into flames in front of my eyes.  But it didn't.

SUCCESSFUL SMOKE TEST!!  IT POWERED UP!!

Power was delivered via a 12v lithium battery that I use in my KX-2.  Plus I had a nice old Norcal dummy load attached.  I was beside myself with glee and joy and the birds were singing, and I saw unicorns in the backyard.  It was a special moment....so I yelled to my wife "HONEY!! IT'S ALIVE!!" and her response was "That's nice." 

So the last thing to do was to put it in the 3D printed case that came with it, and verify the power output.  Using my ever trusty but never rusty WM-2 QRP Watt Meter on the 10W setting, and the Norcal dummy load, I keyed it up and saw a smidge over 5 watts.  My day was made. 


I sent out a few CQ's using my Nye Viking Master Key and got no takers. The band was weak as a baby bird...but...The Reverse Beacon Network was hearing me.  My antenna is a 40m half wave in the attic, and using a LDG auto-tuner to make it do something on 20m. Not a great antenna for 20m. 


So tomorrow I will be ready to have my first QSO on the Pebble rig.  I can hardly wait. 

The Pebble is a $50 radio. Capable of being heard around the world....with the right antenna.  

Visit https://pebblehf.com/ to learn more about this cool little radio. 

73 de KB9BVN
Brian


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