Building and controlling the Pi Pico RX

Some time ago I was handed a free Pi Pico WH processor board.
To test what it could do, I made a simple webserver with it, and it worked ... but I got bored, what would I use it for ? I had no direct application for it.

Somewhat later, I found this online article : https://101-things.readthedocs.io/en/latest/radio_receiver.html  , by Jon Dawson.

Aha! This looked more interesting.
The article describes an HF receiver with minimal hardware and some nice features. Read the full article if you want to find out how it works.

The receiver needs no WiFi, so I ordered a couple of basic Pi Pico boards without WiFi.
The software for the Pi Pico can be found on Jasons' Github page and is very simple to program, just drag the correct file to the Pico like you would do to copy it on a flash drive.

There are versions on Github for the basic Pico (2040 CPU) and for the Pico2 (2350 CPU), see Releases

Still later, there was an article in the Belgian ham magazine CQ-QSO (January 2025, pages 11-13), by a French ham : Anthony, F4GOH. It described a ready made PCB to facilitate building this receiver.

All info is on his Github page , it contains two projects : a simple board for a QSD Detector (Tayloe detector), and the full Pi Pico board I am using.

My good friend Gil, ONL12523 (you may know him from our OST Morse Box and Forty-Niner PLL projects) was prepared to have the circuit boards made in China, and prepare them with the SMD components.

From there, it was only a little work to build a couple of these receivers. The first one was built for a friend, and looked like this:

It was built on a U-shaped chassis made from pieces of PCB. It includes a built-in Li-Ion cell (1800 mAh) with a charger board. There is no filtering at all at the receiver input, so for best results, external bandpass filters can be added.

When everything worked,  I bent a piece of metal (from an old instrument case) to close the box. It is attached with 4 Parker screws in the sides.

This receiver changed owner, so I had to build a second one for myself. 
This time I took  a slightly different approach.

I built a flat box out of PCB pieces, put the encoder on the side, and since everyone always asks "Can we see what's inside?" ... I made a clear cover out of an old CD jewel case.

The cover is press-fit between the left and right sides, so opening it is also very easy.

This also saved me the tedious work to drill and file a rectangular hole for the OLED display.

The two buttons for MENU and EXIT, which are on the PCB were extended with two plastic spacers, where I drilled a fitting hole in the bottom. This way I can reach the buttons through the plastic cover. The rotary encoder is soldered between two small pieces of PCB, which are in turn soldered to the chassis.

Here some pictures of the sides of the box.

Right side with encoder and antenna input (BNC).

Back side with ON/OFF switch and USB-C connector for charging the 1800 mAh Li-Ion cell.

Left side with USB-C connector of the Pi Pico, and the audio output for headphone or external amplified speaker.

Using the Pi Pico Receiver

Even without any filtering , it's amazing what you can do with this receiver. See the user manual and check all the possibilities here

Using my long wire antenna, I get good results on longwave, medium wave and shortwave. 
The only strange effect I noticed, is a kind of "motorboating" noise when no signal is present.
But once a station is tuned in, the noise disappears, so it's not a big problem. 
The results still exceed my expectations, for a receiver that costs less than 20€.

Control Software - Work in progress ... 

Remembering all the combinations of buttons to control this receiver is rather cumbersome, so again we got the help of goood friend Gil ... He has made a basic CAT control program.
It's still in its' beta version, but it's already looking good !

At the moment, it contains a few favourite fixed frequencies, and it can set any frequency via the input box. The small rectangle at the right shows the CAT commands being sent.
Next to the frequency display, the MODE can be set.

At the bottom, the COM port can be selected and the connection can be opened or closed.

You'll have to come back later if you want this program, I'll publish it on my Github page when it's ready.

73,

Luc ON7DQ

ON7DQ Teeth Key for SKCC Weekend Sprint

As a member of the SKCC, I try to be active each month for the "WES", the SKCC Weekend Sprint.
Weekends are often busy with other activities or family visits, but I always try to get at least a few contacts in the log.

What is the Weekend Sprint ? From the SKCC website:

The SKCC WES aims to bring together operators with different skill levels in a regularly scheduled, informal operating event lasting 36 hours. The event starts at 1200 UTC on the 2nd Saturday of each month and ends at 2359 UTC on Sunday. Participants can operate for the full 36 hours.

Of course, all contacts are made with a mechanical key, be it a Straight Key, Bug or Sideswiper (Cootie).

The August edition favours the use of a home built key, giving 5 bonus points for each QSO made with that key. So I had to think of a new key ...

After building a few Cootie designs in the past, I decided to build a new straight key, using my own teeth !

My own teeth, huh ?
Well ,not my actual teeth, but a 3D printed replica I got from my dentist. It was made at the occasion of a dental implant a few years ago.

I did have a varnished plank, that was a first test object when I aquired a router some time ago.

[ Sidenote: I used the router to make a Christmas decoration with 3 LED candles that used 3 AAA batteries EACH. I got rid of all the batteries by connecting all three candles to a 5V adapter, or it can also work on a powerbank. This was the result: ]

Now, how to make a straight key with that set of teeth. I took a few pieces of wood in my garage and started tinkering ... this is the result:

Two bolts (through top and bottom) touching each other do the keying. The spacing is adjustable with the top bolt. Keying force can be adjusted by removing some wood from the top plank, but I think it's just right as it is now. 

The teeth were simply glued to top and bottom with hot melt glue.

No springs attached !

A groove in the bottom houses the wires,  and the wire is fixed with two rubber pads, pressed into the groove.

ON7DQ Friedrichshafen 2025 - Day 11

From Yutz (FR) to Ostend (B), 374 km

To split the ride in two and have some rest, I chose a POTA Park near Brussels

POTA BE-0508 Laarbeekbos

I parked here , pos 50.884172, 4.302819
First I had my lunch, and to quickly set up, I put up my 5.6m Chinese vertical on the fence, the top of the antenna resting between the leaves of the trees. The 4m counterpoise was weaved along the fence.

After 10 QSO's and 1 P2P, it was time to get on the road again ... 

I arrived home at 16:00 local time, and that was the end of a wonderful 11-day SOTA/POTA trip.

I hope you enjoyed the report, and found the information useful.
See you on another trip soon!

73 de Luc, ON7DQ

Go back to overview HERE

 

ON7DQ Friedrichshafen 2025 - Day 10

 From Karlsruhe to Yutz (Thionville), 225 km

DM/RP-411, Hohe Derst - 561m, 4 points

I got some good info from Ingo, DH5ST, about how to get to a nice operating spot for this summit.

Parking is here 49.087561, 7.925953, it is shown on the maps as Wanderparkplatz "Drei Eichen", and can be reached via a narrow forest road, drive carefully and hope that nobody comes from the other direction, hi.

The forest road starts here 49.097757, 7.941459, along the L492 in Böllenborn.

From the parking, follow the paved road upward, but after a big bend in the road it gets a bit tricky : you come at  a point where you can choose from 7 different tracks ! See map below.

The paved road (white line) will take you to the real sumit, near a transmitting tower. But Ingo advised me to take the narrow track just left of this road, it is steep and overgrown in some places, but it takes you via the "Ritterstein" , and finally to a nice  spot in the activation zone, where you will see two benches.

Ritterstein

The choice was not difficult, one bench was in plain sunshine, the other was partly in the shade.

From there, you also have a nice view of the area.

I stayed QRV for 45 minutes, and made 31 QSO's, with 5 S2S.

On the way to the next summit, I stopped for some shopping at the Zweibrücken Fashion Outlet. Parking position is 49.232226, 7.402977 if you're interested.

FL/VO-166, Stromberg - 314m, 1 point

This is an easy drive-up summit. Set your GPS to this position first:  49.454426, 6.347420, and take the Rue Saint Vincent, going in the North-Eastern direction. It becomes a narrow forest road, but continue on until you reach the summit at pos 49.449709, 6.355749.

I arrived there at 15:55 local time, and it was hot hot hot ... 35°C!
Lucky for me, there is a solar installation on the summit, where I could park in the shade, and setup my station a bit further under the shelter. The large grass field is ideal to put up big antennas if you wish.

From the summit you have a wonderful view over the area and the Moselle river. You will also see the nuclear plant of Cattenom to the South-West.

In half an hour, I had 10 QSO's in the log, no S2S but 2 P2P, since this summit is also valid for 2 POTA references. Working EA8ADS was one of the few DX contacts on this trip.

I really wanted to stay the night somewhere in Luxemburg, but couldn't find anything suitable. So I had to make a small detout to Yutz near Thionville, in France.

Tomorrow I'm going home, no more summits but just one POTA activation halfway the road.

Continue reading ... go to DAY 11

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Go back to overview HERE

ON7DQ Friedrichshafen 2025 - Day 9

Trip from Friedrichshafen to Karlsruhe, 297 km

Another hot day was promised!

After I loaded all my stuff from the apartment into my car, I was already sweating like hell, despite it was "only" 24 °C. I left at 09:10 for my first summit.

DM/BW-064, Heersberg - 964m, 10 points

After a 110 km ride through heavy traffic, I arrived at the parking spot at 10:55.
The parking spot is at pos 48.237385, 8.932003, in the village of Burgfelden.

Lots of space, and some trees to let you park in the shade, the temperature was already 27°C.

The walk to a spot in the AZ takes only 15 minutes. I used the same location as suggested by Phil, G4OBK. Only difference ... I couldn't use the nice table to operate, it was simply too hot.

So I found some shade at the small building nearby.

17 QSO's in the log with 5 S2S.

Mystery object

Near the benches and table, I found this strange object. Anyone know what it is ?
Drone launcher, UFO landing platform, SOTA antenna mount ... ?

After the activation, I had a quick picnic near my car, then it was time to start driving to ...

DM/BW-147, Gespaltener Fels - 1000m, 10 points 

This summit is just 20 km to the West from Heersberg.
Being there on a Monday, I could drive up to the parking spot at pos 48.218898, 8.844863, marked on the maps as "Grillplatz".
I'm sure the good shepard would watch over my car ... so I started walking.

The first part is in the woods, but the last part goes over an open grass field, so take sun protection and enough water.
After 30 minutes I reached the summit, and found an old bench to use as an operating spot.

Again , I made 17 QSO's here, with 3 S2S.this time.

After this, it was a 100 km ride to the next one, and then another 66 to my AirBnb in Hagenbach near Karlsruhe. So I better got going ...

DM/BW-054, Hohloh - 984m, 10 points

This is an easy, almost drive up summit.
Best parking is Parking C , at pos 48.707374, 8.427898, I arrived there at 16:40.
Again, being late on a Monday afternoon, the parking was almost deserted, it may be different in a weekend. From there it's only a straight 800m walk with 45m ascent.

At the summit is a hut, which I used to set up my station, the antenna was outside the hut of course.

Several people came by to climb the tower, but nobody paid attention to my operation. 

Here my cosy indoor shack ...

I had to hurry a little, so made it a short activation. In just 15 minutes I had 13 QSO' s in the log, and just 1 S2S, still a good result.

 I left the parking at 17:30 local time, got me some food in a supermarket, and arrived at my AirBnb at  19:00. Temperature had risen to 35°C ... good that I still had that fan 😄

Continue reading on DAY 10

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Go back to overview HERE

ON7DQ Friedrichshafen 2025 - Day 8

The one with the flat tyre and  ... a second Mountain Goat !

It was Sunday morning, and I had planned a day trip to Bavaria, to activate two summits that I needed for complete : DL/AL-273, Laubenberg (1 point) and DL/AL-148, Riedholzer Kugel (2 points).
With 3 points, these two summits would have brought my activator score at 1999 points, just one point short of another Mountain Goat.

But my car decided otherwise. 
The evening before I got this warning about a tyre with low pressure, so I first went to check my car.
When I looked around the tyre, I found a screw, which must have caused the drop in pressure, but it was not completely flat.

Since my car no longer has a spare tyre, I phoned the Toyota Assistance number in Belgium, and must admit they provide an excellent service. Around 10:30, a man from German ADAC came by to repair the tyre ... for free ... and on a Sunday morning, GREAT!

OK, I could drive again, but by then, it was too late to start my planned trip, and I decided to go to the nearest summit, trying to keep cool ... it was already 30°C in the shade.

DM/BW-348, Gehrenberg - 754m, 8 Points

I drove to my regular parking spot near the summit at position  47.742628, 9.423206.
I verified again : there is no forbidding sign if you follow the Hinterharresheim farm road, which starts at pos 47.747471, 9.403920 along the Gehrenbergstrasse. The small road becomes a gravel road, called Turmweg.

NOTE : I heard a few activators call CQ SOTA on 2m, telling they were on a lookout tower ...

There is no lookout tower on the summit of Gehrenberg, the tower "Gehrenbergturm" is not in the activation zone. Also the place called Gehrenberg on the maps, at pos 47.7371,9.39977 is NOT the summit. All very confusing, I know.

I found a spot to setup a bit away from the real summit, where often walkers and mountainbikers come by, it can get busy at the top !

Even being hidden somewhat, I got several visitors, hams and non-hams alike, who were interested in my setup. One of those was a mountainbiker AND a HAM, it was Yannick DO9YAN. He was recently licensed, and came to activate the summit on 2m, using an FT70 and a 4-element Anjo logperiodic antenna (the same antenna that I sometimes use).

I made 30 QSO's with an incredible 15 Summit-toSummit contacts, WOW !
That made my day , but wait ...

I hadn't been paying attention to my score, so with the 8 points of this summit, I made it to second Mountain Goat a bit unexpectedly.
The honour should go to Harald, DG1YBN, who was my fourth contact. He called me from his mobile on 2m FM.

Not knowing at the time that I was already there, I didn't make any special pictures, also no champagne ... hi.

After being on the summit for 3 hours, I decided to go to my apartment and take some rest.
It was 32°C when I arrived there. Also, I had some preparation to do for the next day : a trip from Friedrichshafen to Karlsruhe, with more summits of course!

Continue reading on DAY 9

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Go back to overview HERE

ON7DQ Friedrichshafen 2025 - Day 7

I had taken my folding bike, so no car driving today ... only visiting ...

The Ham Radio fair

There is not so much to write about the fair, so I'll leave you with a few pictures.

CW keys for everyone

This was a heartwarming piece of equipment for me, I have been teaching a transmission line course for over 30 years, which includes teaching about the Smith Diagram.
Of course, you can buy a 30$ nanoVNA now, which will show the Smith Diagram as well.

In the afternoon was the SOTA meeting

Lucky that there was also the SOTA booth, where it was all about SOTA

The raflle, where some nice prizes could be won. Joe, OE5JFE is holding his hand above the 4 ON7DQ Clothespeg Paddles that I made for this edition of the raffle.

Nice to see a happy Uli, DC1UH, winning a QMX transceiver from QRP Labs

After a day at the fair, I quickly went across the street to see a Zeppelin take off, always a nice experience. Click the picture to see a short video of the Zeppelin.

And of course some good food and a beer made the day complete !

And I lied at the beginning of this post ... I did use the car to drive to a restaurant, some 10 km outside of Friedrichshafen. When returning, I got an alarming message on my display, that one of my tyres had a too low pressure. Oh boy !

But it was already getting dark, so I decided to look into that the next morning ...

Continue reading on DAY 8

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Go back to overview HERE