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.

• Hardware: PEBBLE 20m HF Transceiver by Barb WB2CBA
• Firmware: usdx-pebblehf by Mike N4FFF and based on uSDX by Guido PE1NNZ
• 3D Case: Print Your Own Pebble HF Case

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. 

UPDATE FOR 10/15/2026

I made my first contacts this morning, the first was to K5DOE, Jeff at Deer Camp in Tate Hills Park near Magnolia Arkansas.  Jeff awarded me with a 599. 

My next contact was with Joey WN4AT, he was at Oak Mountain State Park near Sterrett Alabama.  Joey gave me a 559.  

The band is very mushy today, I switched between my K2 and the Pebble and the receive audio was about the same on both....low and somewhat muffled.  The numbers for right now are not the best, with the A index over 8 it gets hard to hear. 

SSN:124 SFI:123 A:10 K:3

73 de KB9BVN

Brian

I'm back! Took July off!

KB9BVN at US-4183 

Well I took July off from POTA, we just had too many things going on and did not have time to get out and activate any at all. So I have been looking forward to hitting the trail again and getting outdoors with my portable station and making some contacts. Besides, it was pushing 100F most of the month. 

Today I went back to US-4183 Atterbury Fish and Wildlife Area in southern Johnson County between the city of Franklin and Edinburgh.  This was my 49th time to activate from this location.  I can't help it, it's less than 30 minutes from home, so why not? 

I drove around a bit looking for a site with some appreciable shade, I found a nice parking area and setup my station in the shade of a giant Walnut tree.  The temperature was a balmy 83F and the horse flies were thick as peanut butter on a popsicle.  Once setup I decided I would do some hunting before I went to the POTA website and spotted myself.  It took me almost an hour to contact six other parks on 20m, the bands were very muffled, and the speaker in the KX-2 is not super loud.  Next time I will bring headphones, but I hate using them when it is so hot. 

I spotted myself on 10110 Khz at first, this is the 30m band, and when it's good, it's real good.  Today that was not the case.  The column marked SNR is basically a indication of my signal strength being heard in various locations on the map. Usually for me, anything under 11 or 12 db is not going to get me any contacts. I ended up with ONE.  That was it. 

See below: 

Then I decided to give 40m a try, I spotted myself on 7063 Khz and started calling CQ.  This went on for about 15 minutes with no takers then it was like someone turned on a switch in North Carolina.  I got four more contacts in about 5 minutes all from North Carolina!  My SNR rating never did get much above 10-12db.  After I logged contact number 11, I had been at it for almost 90 minutes. I have usually gotten my minimum of 10 contacts in less than 15-20 minutes.  Not today.  

You can see my 40m map below:

I was using the Eagle One telescoping vertical mounted to my hitch on the beloved POTAmobile, which is old enough to vote.  The old 2006 Trailblazer cracked 200,000 miles last month...I think I need to start looking for a replacement soon. I buy used, then drive the wheels off. I have owned this one for the last 12 years. 

One last photo...here's the logbook and my KX-2 in action! 

Until next time, have a great summer, what's left of it.  Only 49 days of summer left...USE THEM WELL!! 

73 de KB9BVN
Brian

Another day at Atterbury Fish and Wildlife Area

 

Another Day in the Great Outdoors at Atterbury

Another beautiful day today, low humidity, and temps in the upper 60's to mid 70's. Bright sun, and a slight breeze. So nice.  So I packed up the gear and headed to the park at about 12:30pm, drove around for a bit looking for a shady spot to erect the POTA station.  I stopped at several familiar places, Beaver Bottom Lake had no shade and about 15 people fishing off the dock.  I did not see any fish being caught but they were having a great time. I then drove over to Stone Arch Lake, and the parking area was also without any shade.  Since it was about 1PM the sun was almost directly overhead. I finally landed at Mink Meadow Marsh, under the shade of a big walnut tree that was hanging over one corner of the parking area. 

Once again at Mink Meadow Marsh

So today I decided I was going to make this a quick one and I would go ahead and use my Alex Loop antenna.  It's very easy to setup and tune, and goes a lot faster than the hitch mounted portable vertical. 

Alex Loop with my Elecraft KX-2 radio in its handy pouch

After I got the antenna assembled and in place, I broke out the KX-2 and remember to turn off the auto tuner.  When you are using a Magnetic Loop antenna, you tune it by adjusting the variable capacitor in the rectangular box at the bottom of the loop.  This is why you must set the autotnier in the radio to BYPASS.  I started out on 20 meters, 14.058 Mhz to be exact.  I got on the air at 1:13PM EDT and almost immediately started making contacts.  I worked Idaho, Newfoundland, Maine, Oregon, and Nevada in the first ten minutes.  Not bad for a Mag Loop and 10 watts. The band was really working well this afternoon.  At 1:40PM I shut the station down with 12 contacts, enough to qualify as an activation of this park, my 48th time to activate this park.

KX-2 radio and log book, ready to go to work! 

From the looks of my contact mapping, I had the antenna angled so it was radiating East-West. Worked both coasts and a bunch in the middle. 

Weatherman says we have more severe weather on the way, and to expect rain and storms the next three days, with over 3 inches of rain expected in total.  Indiana has logged 71 tornadoes so far this year.  We had one last Friday night the ripped through the Morgan Monroe State Forest, cutting a swath of knocked down trees 1/4 mile wide and about 8 miles long.  I will try to make to MMSF next month to do some POTA work....but I want to give the DNR a few weeks to get things cleaned up a little bit. 

Until next time, 73 es Best DX to you! 

Brian KB9BVN

Beautiful Day to be Outdoors!

 

KB9BVN at the key, ready to POTA!

Gosh what a great day weather wise.  Here in central Indiana it was over 90 degrees every day last week, and every night we had torrential rain and thunderstorms.  One system even spawned about half a dozen tornadoes in the northern third of the state. Fortunately no one was killed. 

Here is it Monday again, or Saturday to those of us that are retired, and the temperature was 65 degrees when I rose this morning.  Sunny, and cool...perfect day for POTA at the park.  So today I headed back to US-4183 Atterbury Fish and Wildlife Area in southern Johnson County.  I used the Eagle One portable vertical, the KX-2 radio, and the KX-2 paddles.  Getting the antenna erected and the operating position setup took about fifteen minutes or so. 

The location I chose today was called "Mallard Marsh".  I think I have operated from here before but it has been a couple years or so since the last visit.  I took a short hike back to the lake and the marsh area, and using the Merlin application on my phone I logged 7 different bird species. Including a rare to find these days, Bob White Quail.  I heard it but I never found the location for a picture.  Maybe next time. 

Mallard Marsh has no restroom, and limited parking 

The sky was really beautiful this morning, and the clouds were rolling but no rain predicted here until maybe Thursday. 

Looking east at the beautiful sky and the slow moving clouds

Before I started operating I took a quick hike down to the pond and by the marsh.  Pictured here at the current state of things, this place is usually crowded with ducks and geese and all kinds of birds in the Spring and early Summer. I heard several bullfrogs but did not see them. 

Here is a shot of my setup with the Eagle One vertical.  It mounts to my trailer hitch, and has a large clamp that clamps on the ground side of the antenna, making my Trailblazer in to a counterpoise, or radial if you prefer.  I also clip on 2 wires made from 18g speaker wire, each about 22-23 feet in length to help the antenna tune up better on 40m.  One of the wires I lay across the top of the vehicle and out over the hood...gives it some elevation.  Does it help? I don't know but I like to think it does.  The other wire I just deploy to the ground and let it lay there. 

Today the bands seemed to be in OK shape.  I started out on 40 meters at about 12:15PM EDT.  It took about 20 minutes to get the first three contacts.  Granted I was only running 10 watts.  I switched to 20 meters (longer distance) and immediately worked California, Florida, and Nebraska.  Then 20 meters seemed to go quiet, so I switched back to 40m.  

After about 90 mins, the DNR showed up with a John Deere mower...and proceeded to mow all around me while I was operating.  The noise being generated by the mower engine was enough to cover up anything I might hear.  The DNR lad was very nice and I showed him what I was doing and how much fun amateur radio is.  So at about ten until two o'clock, I packed it in.  Finished with 13 contacts, all I need is ten for a valid activation.  Done and Done. 

Here's a map of my contacts from today:

It is supposed to be nice again tomorrow, so I may try to run down to the fishery in Martinsville Indiana, or maybe even down to Lake Monroe in Bloomington. 

Until the next one,  may you have the best DX and all the contacts you need! 

73 de KB9BVN

Brian

Tough Sledding!

US-4183 Teal Marsh 

Headed out to Atterbury again on May 7th in hopes of  better conditions, and more contacts.  Did not work out that way though.  Took me almost an hour and a half to make 10 contacts and get this park activation in the books.  Furthest contact was Wyoming, and that was another POTA operator working from Miles Landing BLM Recreation area.  Not too bad.  

I checked with the Reverse Beacon site and found my signal was being heard but it was very weak due to poor propagation characteristics.  This Solar Cycle 25 is beginning to wind down.  Each Solar cycle is about 11 years in length and the current cycle actually started back in December 2019.  It hit the peak about 3 or 4 months ago, and now we are starting the 5 year slide to minimum conditions.  

A signal to noise ratio under 10db is usually pretty hard to copy.   So I was getting out, just not getting out very loud.  

Here is a map of my contacts for this outing.  The antenna I was using was the 33 foot tall, hitch mounted vertical antenna.  I had a couple 16 foot ground wires attached as well, we call these radials. 

Map of 10 contacts from May 7th at US-4183 - Took about 90 minutes

So while I was waiting to make contacts I found this Painted Turtle sunning itself in the bean field, this guy was about 15 inches from nose to tail. 

Painted turtle - Catching a few rays in the bean field!

It was slow going, but at least I had some nice scenery to enjoy, and a plethora of different birds enjoying the marsh. 

Well that's about it from this outing...until next time, may the propagation be with you! 

73 de KB9BVN

So that's an R1 Radio Blackout Event

KB9BVN at US-4183 Atterbury FAWA

Woke up this morning and the birds were chirping and the sun was shining and the day was looking like a beautiful April day....so why not load up the gear and head out for a Parks on the Air outing? 

So normally when I go out for a POTA activation, I usually have my 10 required contacts within 15-20 minutes, sometimes even faster. Today was going to be much different.  I never check atmospheric conditions before I play radio, I don't want to get jinxed.  Well, today is a day I should have looked, but even if I had looked I doubt if it would have stopped me from playing radio in the outdoors today.  

Here is what the conditions report was showing:  SSN:154 SFI:148 A:9 K:1 - what this means is there were 154 sunspots active, and the Solar Flare Index was 148.  With this kind of sunspot activity being this high, this usually means noisy conditions.  Which in and of itself isn't that horrible.  You like to see the A Index 5 or less, mush over 5 and you'll heard a lot more signal fading (up and down).   What I did not know was the earth was in the middle of an R1 Radio Blackout.  

An R1 (Minor) radio blackout is the lowest level of space weather event on the NOAA Space Weather Scale, caused by an M-class solar flare. These flares release X-rays and ultraviolet light, ionizing the lower D-layer of Earth's ionosphere. This ionization causes High Frequency (HF) radio signals to be absorbed or degraded, resulting in weak or brief blackouts, mainly impacting sunlit areas.

This explains why it took me almost 2 hours to make 10 contacts.  None of them outside the United States, and all contacts were made on the 20m band.  

Three of the contacts were not POTA hunters, they were working the Florida QSO Party, but as we say in the POTA world, a contact is a contact.  So they count toward the 10. 

Signals were WAY down, and the fading and noise was ever present.  I'm amazed that my little 10 watts was getting out at all but my reverse beacon logs showed in some places I was booming in and in some places I was not even noticed. 

On the bright side, I enjoyed a few hours in the outdoors, got to watch some blue jays, some squirrels, a big black snake, and some geese.  Plus I had a nice picnic lunch by one of the lakes, it was a peanut butter sandwich and a nice crisp Gala Apple.  Made the trip and the time all worth it! 

Oh and I forgot my metal folding chair.  I had taken it out of the POTA mobile so I had something to sit on during our fish fry a few weeks ago.  So here's my operating position...while I sat on an overturned pickle bucket...not very comfortable! 

Well that's it until next time!  Hoping for better conditions soon! 

de KB9BVN

Brian