Hamclock for Raspberry Pi ... the easy way!

In January 2026, Elwood Downey WB0OEW sadly passed away. As the developer, this signalled an impending end to his beloved ClearSkyInstitute HamClock project that had run for many years. Not wishing to lose such a valuable resource in the ham community, Dave N9DK has developed open-hamclock-backend. Your pre-installed Hamclock, or new installation, will seamlessly continue as before.

There are now several Hamclock variations. If you want accuracy of data, only OHB fits the bill. Same Hamclock frontend, the ultimate backend. Being Linux, the tendency for programmers is to be ambiguous in their explanations. Even OHB suffers from this with not just the OHB GitHub page but also two associated websites proffering complex scripts and commands when actually there exists the easy way.

If you need a new or fresh install, use Raspberry Pi Imager from https://www.raspberrypi.com/software/ and because I recommend that you have Hamclock start automatically on the Pi at boot, avoid selecting the latest Trixie. In this distribution some important functions have been removed or are handled differently. Select instead Bookworm 64-bit with Desktop. After installing the OS, bring it up to date by opening Terminal and using the command sudo apt update && sudo apt upgrade. Now reboot your Pi. Then amend your host file so that it points to open-hamclock-backend instead of ClearSkyInstitute. Use sudo nano /etc/hosts to open the file in the nano editor. Add 44.32.64.64 clearskyinstitute.com on a single new line and when finished press CTRL-X, Y, enter which will save the change.

As at April 2026, the source code appears to no longer be available at ClearSkyInstitute. Fortunately, I have it in my Dropbox: https://www.dropbox.com/scl/fi/qt270dddqyo5kcjtxaldi/hamclock-main.zip?rlkey=mplgegz413yebfiwso6unui4s&st=wqfdfci6&dl=0

You do not need to login, instead click ‘continue with download’ and the zip file will transfer to your Downloads folder. Extract it and open a Terminal window at the ESPHamClock folder. Enter each of these commands in turn:

make help

make hamclock-1600x960

or whatever your preferred size is from the presented list

sudo make install

Hamclock will be installed - try in Terminal the command /usr/local/bin/hamclock & If you amended your host file, OHB will be your server. If not, set it in the properties of a desktop icon.

To get a desktop icon, open the ESPHamClock folder in the Pi file manager and copy the HamClock file to the desktop (copy & paste). Without the host file change, you can set the server in the icon by right clicking and opening properties. Go to the Desktop Entry tab. In the command box, change the command to /usr/local/bin/hamclock -b ohb.hamclock.app:80 and press OK.

Autostart if you want Hamclock to start on Pi launch: open a Terminal window then

mkdir -p ~/.config/autostart (if it does not already exist, otherwise go to it)

nano ~/.config/autostart/hamclock.desktop

[Desktop Entry]

Name=HamClock

Exec=/usr/local/bin/hamclock

Icon=/home/pi/.hamclock/hamclock.png

Terminal=false

Type=Application

Save and exit with Ctrl+O, Enter, Ctrl+X .

With Hamclock directed to OHB, using the external server, reboot your Pi.

All done. You have done it the easy way!

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Accuracy of the Kp solar index value.

The Space Weather Prediction Center updates the estimated Kp value every 3 hours starting at midnight UTC. The exact timing can vary from 1 minute past the hour to as much as 8 minutes past. OHB therefore pulls data at 10 minutes past the hour to ensure the update is grabbed. The Hamclock application refreshes from its server, originally CSI but now OHB, every 45 minutes. Conceivably it could have taken up to 45 minutes for Hamclock to show the latest value. But if you downloaded from my DropBox, the KP_INTERVAL has been edited from 2500 seconds to 600 seconds. When OHB pulls the new Kp value from SWPC, your Hamclock will update between 1 and 10 minutes later. Therefore, at the latest, Kp will be up to date within 20 minutes of SWPC posting the new value.

With this amendment, open-hamclock-backend is the most accurate of all the Hamclock variants with not just Kp being up to date but also the other solar data indices having precision presentation. OHB is actually a step forward from the original CSI Hamclock.

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Want to run your own local open-hamclock-backend server?

OHB can be deployed on a host OS. But there are many distributions out there and potentially the OHB dependencies can cause issues with your system, especially when updating. The generally accepted method of managing this is to run the service in a Docker container.

Docker is easily installed. Follow the short instructions at: https://pimylifeup.com/raspberry-pi-docker/#installing-docker-to-the-raspberry-pi

Next, install OHB using these commands, after first checking for the latest version number at https://github.com/komacke/open-hamclock-backend/releases

curl -sLO https://github.com/komacke/open-hamclock-backend/releases/download/v1.0.7/manage-ohb-docker-v1.0.7.sh (assuming version 1.0.7 is the latest)

mv manage-ohb-docker-v1.0.7.sh manage-ohb-docker.sh (plug in the latest version, same as above)

chmod +x manage-ohb-docker.sh

./manage-ohb-docker.sh install -t <insert version here> so for example your command might be

./manage-ohb-docker.sh install -t v1.0.7

Next, remove any hosts file change so that Hamclock does not connect externally. Open the properties of the Hamclock desktop icon and go to the Desktop Entry tab. In the command box, change the command to /usr/local/bin/hamclock -b localhost:80 and press OK. Your Hamclock will, on the next reboot, connect to your own OHB server. There is no real advantage to having a local OHB server but anyway the possibility is there and the above sets it up for you.

When there are OHB updates, seen on the releases page as above, open Terminal and execute the three commands listed under the section “versions starting with v0.24” except that the final command should include the update version like this: ./manage-ohb-docker.sh upgrade -t v1.0.7 or whatever the version currently happens to be.

With Hamclock directed to your own OHB server, reboot your Pi.

All done. You have done it the easy way!

About

The creators of this website are long time Hamclock users who, faced with needing to find a method of keeping our displays from going dark in June '26, looked for alternative sources but were bamboozled by Linux commands, scripts and other unnecessary complications. We decided to find out how to do it the easy way.