DX Alarm Clock Part 2 – Hardware

The DX Alarm Clock

The DX Alarm Clock

I recently wrote a blog article about the DX Alarm Clock software – here is Part 2 of the Series on the how I built the hardware for the DX Alarm Clock.

DX Alarm Clock Hardware Components

The DX Alarm Clock is based on a Raspberry Pi 3 computer and an Adafruit Pi-TFT Touch Screen Display.  The list of components, along with links is below.  Since I built the Raspberry Pi almost a year ago and technology is always advancing, some of the parts are no longer available or have better replacements available.  I’ll provide information on what I used and a recommended replacement.  Approximate prices are included.


Rapberry Pi 3

Rapberry Pi 3


Motherboard: Raspberry Pi 3 ($35) – includes a 1.2 GHz 64-bit quad-core ARM CPU, Build in WiFi, Ethernet, 4 USB Ports, an HDMI port and audio port (3.5″) and Bluetooth.

Also you will need a power adapter  ($10) and Class 10 Micro SD card ($15) for the Raspberry Pi.  Ours is a SanDisk Ultra 64GB Micro SD Card.

Pi-TFT Touch Screen Display

Pi-TFT Touch Screen Display

Display: Adafruit Pi-TFT 2.8″ Display with Capacitive Touch Screen ($45).  A slightly larger, 3.5″ display is now available.

PiBow Case

PiBow Case for Raspberry Pi and Touch Screen Display

Case: Pimoroni PiBow Case for Raspberry Pi and Pi-TFT Display($20)

Kinivo Speaker

Kinivo Portable Speaker

Portable Speaker:  Any small portable/rechargeable speaker will do.  Mine is a Kinivo, but it is no longer available.  Any small speaker will do as long as it is Bluetooth or has a 3.5″ stereo connector.


Raspberry Pi Development Environment

Raspberry Pi Development Environment

Raspberry Pi Development Environment

After constructing the Raspberry Pi, case and TFT Display, the next step was to connect it to a monitor via the HDMI port, a mouse via one of the USB ports and to a Bluetooth keyboard.   Then I loaded the Raspbian Operating System onto the Raspberry Pi via the micro SD card.  I first copied the OS to the Micro SD card using a PC or Mac and then inserted the card into the Raspberry Pi and booted from it.  You can find a good tutorial on how to do this at https://www.raspberrypi.org/learning/software-guide/quickstart/

Once Raspbian is installed, you will have a windows like GUI (Graphical User Interface) environment with a web browser, and a number of additional applications included.

This gave me a development environment that I could use to build and test the DX Alarm Clock software.  I used the Python language to develop the software.  I used the Python IDLE development environment, which is included in the Raspbian OS.

Interested in Raspberry Pi Amateur Radio Projects?  See the article on a Raspberry Pi Satellite Rotator Interface.

Raspberry Pi Satellite Rotator Interface

MacDoppler and GHTracker

MacDoppler and GHTracker

We’ve been using our Portable Satellite Station 2.0 for some time now and it works great. One area that can be improved is the interface between the MacDoppler Satellite Tracking program we use and the GHTracker application which controls the Green Heron Engineering RT-21 Az/El Rotator Controller in our setup. Our initial approach was to run the GHTracker app under Windows/VMWare on the same MacBook Air laptop that runs MacDoppler. While this approach works ok, it was more complex and less reliable than we had hoped.

Fortunately, the interface between MacDoppler and GHTracker uses a UDP-based interface which will run over an IP network.

GHTracker Running On A Raspberry Pi 3

GHTracker Running On A Raspberry Pi 3

Anita, AB1QB got great results using a Raspberry Pi 2 with a Touch Screen for her DX Alarm Clock Project so I decided to do something similar with GHTracker. The new Raspberry Pi 3 Model B boards feature a built-in WiFi networking interface and four USB ports which made the RPi 3 a perfect platform for this project. An email exchange with Jeff at Green Heron Engineering confirmed that GHTracker could be made to run under Linux on the Raspberry Pi (RPi).

We wanted a compact package that did not require anything but a power supply to run the final project. There are lots of great choices of parts to build a Raspberry Pi system. Here’s what we used:

Total cost for all of the parts was $120.

Assembly of the case and the hardware was straightforward. The folks at Adafruit provide a pre-built Jesse Linux image for the RPi which includes the necessary driver for the Touch Screen Display.

After a bit of configuration work and the creation of a few shell scripts to make it easy to boot the RPi to a HDMI display or to the Touch Display, we were ready to install the GHTracker App. we also enabled the VNC Server on the RPi so that we could use a VNC Client application on our MacBook Air in place of directly connecting a display, keyboard, and mouse to the RPi. Finally, we installed Samba on our RPi to allow files to be moved between our other computers and the RPi.

GHTracker Running on the Raspberry Pi

GHTracker Running on the Raspberry Pi

Jeff at Green Heron Engineering provided a copy of GHTracker V1.23 and the necessary serial interface library to enable its use on the RPi. Jeff is planning to make a tar file available with GHTracker and the library in the near future. We did some configuration work on LXDE (the GUI interface for Linux that runs on the RPi) automatically run GHTracker whenever the RPi is booted up. We also optimized the GUI for the sole purpose of running GHTracker on the Touch Screen Display. Finally, we configured the Ethernet and WiFi interfaces on the RPi to work with our home network and with our LTE Hotspot modem.

RPi GHTracker Test Setup

RPi GHTracker Test Setup

With all of the software work done, it was time to test the combination with our Satellite Rotator System. The setup worked on the first try using a WiFi network connection between the MacBook Air Laptop running MacDoppler and the RPi. The USB-based serial ports which control Azimuth and Elevation direction of the rotators worked as soon as they were plugged into the RPi. Also, the touchscreen interface works well with the GHTracker App making the combination easy to use.

MacDoppler and GHTracker via VNC

MacDoppler and GHTracker via VNC

The VNC Client/Server combination allows us to work with the software on the RPi right form our MacBook Air laptop. It also makes for a nice display for monitoring the GHTracker App’s operation from the Mac.

Other articles in the Portable Satellite Station series include:

You may also be interested in the satellite station at our home QTH. You can read more about that here.

Thanks to the help from Jeff at Green Heron Engineering, this project was very easy to do and worked out well. The Raspberry Pi 3 platform is very powerful and relatively easy to work with. It makes a great start for many Ham Radio projects. Also, there is a wealth of online documentation, how-to information, and open source software for the RPi. I hope that some of our readers will give the RPi a try!

Fred, AB1OC

Why Ham Radio?

Scorpion SA-680 Screwdriver Antenna

Fred’s Truck with Antenna

Every so often, I drive Fred’s truck into work and people ask me what that big antenna on the back of the truck is for. I explain to them that it is for Ham Radio.  But the reply is usually, why ham radio – isn’t that outdated technology?  We have cell phones and IM, etc…what do we need Ham Radio for?  So I thought I would put down my thoughts as a relatively new Ham about why I enjoy spending so much of my time with Ham Radio.


Amateur Radio for Public Service

Public Service

The number one reason we still need Ham Radio along with all the other technology we now have is for public service.  When there is a disaster and cell phones, television, etc are all not working, Ham Radio operators provide the critical communication.

Ham Radio operators help locally to keep hospitals and first responders in contact with each other to help those affected by the disaster.

Hams also use our ability to communicate around the world on HF bands to help family members around the world to get in touch with loved ones affected by a disaster.

Ham Radio operators have been on the scene helping in every disaster from the earthquakes in Nepal to the recent flooding in California.


Amateur Radio Cube Satellites

Technology and the Maker Movement

I only became a Ham 5 years ago but many of my fellow Ham Radio operators got their license when they were in their early teens and used what they learned to launch their careers. Many have had very successful careers in STEM fields, all launched by their interest in Ham Radio at a young age.  As technology advances, so does the technology used in our hobby.   We even have a nobel laureate, Joe Taylor K1JT who is a ham. Joe has developed weak signal digital communication modes that let us communicate by bouncing signals off the moon!

As technology has advanced, so has the use of it in Ham Radio.   Most Ham Radio operators have one or more computers in their shack.  Many also have a software designed radio (SDR), where much of the radio functionality is implemented using Software, we use sound cards to run digital modes, which are a lot like texting over the radio, and we use the internet extensively as part of operating.  We can also make contacts through satellites orbiting the earth and even the International Space Station.

Most hams love do-it-yourself technical projects, including building a station, home brewing an antenna, building a radio or other station component.  In my day job, I am a program manager for software development projects, but its been a while since I have built anything. As a Ham I taught myself how to code in Python and about the Raspberry Pi and I built the DX Alarm Clock.


QSL Card from VK6LC in Western Australia

International Camaraderie

One of the coolest things about being an amateur radio operator is that you can communicate with other hams all over the world. Ham Radio is an international community where we all have something in common to talk about – our stations and why we enjoy ham radio.    The QSL card above is from a memorable QSO with Mal, VK6LC, from Western Australia, who was the last contact that I needed for a Worked All Zones award.  I must have talked to him for 1/2 hour about his town in Australia and his pet kangaroos!


Amateur Radio Map of the World

Geography Lesson

I have learned much about geography from being on the air and trying to contact as many countries as I can.  There are 339 DX Entities, which are countries or other geographical entities and I have learned where each one is in order to understand where propagation will allow me make a contact.  I have learned a great deal about world geography. Through exchanging QSL cards often get to see photos from so many areas of the world.


DXCC Challenge Award Plaque

Achievement – DXing and Contesting

DXing and Contesting provide a sense of achievement and exciting opportunity for competition. Many Hams work toward operating awards. You can get an operating award for contacting all 50 states, contacting 100 or more countries, contacting Islands, cities in Japan, countries in Asia, or anything else you can imagine.  Each of these operating awards provides a sense of accomplishment and helps to build skills.  Contesting builds skills through competition among Hams to see who can make the most contacts with the most places in 24 or 48 hours. Contesting also improves our operating skills and teaches us to copy callsigns and additional data accurately.


Teaching a License Class

Teaching Licensing Classes – Passing it On

Recently I have joined a team of club members who teach license classes to others who want to get licensed or upgrade their existing Amateur Radio licenses.  Teaching provides a way to improve my presentation skills and also helps me to really understand the material that we teach about Amateur Radio.  It is always a thrill at the end of the class to see so many people earn their licenses or upgrades.

There are so many interesting aspects of Ham Radio which is what makes is such a great hobby.  Getting your license can open up a world of possibilities.  Upgrading to a new license class provides more opportunities to communicate over longer distances.  Ham Radio clubs, including our local club, the Nashua Area Radio Club,  provide many resources to help you get your first licenseupgrade to a new license class, and learn about the many aspects of our hobby.

The DX Alarm Clock – Part 1 Software


The DX Alarm Clock

I have been a Ham for 5 years and my favorite thing to do is chase DX. As a new Ham it was always a thrill to work a new DXCC, but now that I have over 280 DXCCs and over 1000 band points, it is a little more difficult to find a new one. Add to that the fact that I am trying to get a DXCC in 80m and 160m., which are usually open when I am asleep. I created the DX Alarm Clock as a way to get notified that there is something new on the air when I am not down in the shack.  This article will talk about how I developed the software for the DX Alarm Clock.  Part 2 will talk about the building the Raspberry Pi based Hardware and loading the OS.

The DX Alarm Clock is a Python software program running on a Raspberry Pi that gathers data online about my log and what is on the spotting network and uses that data to alert me when there is a “new one” on the air.


DX Alarm Clock Architecture

The ClubLog website provides a light DX Cluster website called DXLite, which has an XML Interface. The DX Alarm Clock uses this interface to get the current spots. The software uses the Developer API from ClubLog to get a JSON matrix of all DXCC entities by band indicating whether I have worked, confirmed or verified each band-entity. The software loops through all of the spots returned by DXLite and looks each DXCC up in the JSON ClubLog matrix. I also use the QRZ.com XML Interface to get additional information for each callsign that is spotted, like the state.


DXCC Configuration Screen

The DX Alarm Clock uses tkinter/ttk for the GUI.  I used the Notebook widget to create a multi-tab GUI.  There is a tab for configuring filters for DX Entity. The user can choose all New DXCCs, as well as specific bands and nodes to provide alerts for.


WAS Configuration Screen

There is another tab for configuring filters for WAS. ClubLog has no log look up capability based on US State so the WAS filter lets you create a list of States and associated bands to provide alerts for.


Notification Configuration Screen

The Notification tab allows configuration of what notifications the user would like to receive. The user can specify a separate email address for New DXCCs, New Band Points, and New US States. This allows alerts to be sent to email accounts or as SMS texts. You can also configure the sounds the the DX Alarm Clock itself makes to “wake you up” when that ATNO or new Band Point is spotted.

The DXAlarm clock wakes up every 5 minutes and gets the latest spots from the DXLite Cluster. It checks each spot against the ClubLog log and if there is a match based on the configure filters, it sounds the alert, and then speaks the alarm, giving you the Callsign, DXCC Entity, Band and Mode.   A simple text to speech package called flite (festival-lite) was used to implement the speech on the Raspberry Pi.



Alert Screen

It also puts a message with these details and the Frequency, UTC Date/Time, Spotter and Comment on the display.


Text Notification to iPhone

Additionally it sends this information as an email to the configured email address, which results in a text or email.



Apple Watch Alert

I can even get the alert on my Apple Watch.


Filtered Spots Display

Once all spots are processed, it keeps a running list of all spots that resulted in alerts on the main screen. Spots are aged out if they do not recur over time.


DX Alarm Clock Hardware

The DX Alarm Clock just alerted me that ZC4SB is on 20m – that’s an ATNO!  Got to go down to the shack and work him!    Stay tuned for Part 2 of this post on the DXAlarm Clock Raspberry Pi based hardware and on setting up the Raspberry Pi OS.

Anita, AB1QB

Giving Back To Amateur Radio

Nashua Area Radio Club - 2016 Year In Review

Nashua Area Radio Club – 2016 Highlights

Anita, AB1QB and I have spent a good deal of time this past year helping the Nashua Area Radio Club here in Nashua, NH USA as a way to give back to the Amateur Radio Service. Our work with the Nashua ARC has produced some of the most enjoyable and memorable times of our Amateur Radio experience.

Teaching Nashua Area Radio Club Hosted License Classes

Teaching Nashua Area Radio Club Hosted License Classes

In particular, our contributions to the work that our club is doing around helping people to earn licenses and introducing young people to the Amateur Radio Service has been most rewarding.

Abby, KC1FFX Operating a GOTA Station During Nashua ARC Youth Day

Abby, KC1FFX Operating our GOTA Station during Nashua ARC Youth Day

We recently produced a 2016 Highlights video about our Club’s activities and the club’s contributions to the Amateur Radio hobby. We thought that some of our readers here might enjoy the video. You can view it on our club’s home page here.


Fred, AB1OC


Building An Amplifier

Elecraft KPA500 Amplifier

Elecraft KPA500 Amplifier

I have been planning to add a medium power HF Amplifier to our station for some time now. The plan was to use an amplifier of this type for two purposes –  as an amplifier for Anita’s (AB1QB’s) position at our home station and to have an amplifier that we could take along on DXpeditions and other portable operations. After doing some research, it looked like the Elecraft KPA500 Amplifier would be ideal for this. It is small in size, can operate using either 120 VAC or 240 VAC power and has a quite reasonable weight of 26 lbs.  After dropping some not so subtle hints, I received a KPA500 kit as a holiday gift.

The Elecraft KPA500 is a no-solder kit and requires 4 – 6 hours to assemble. Just for fun, I decided to make a time-lapse video of the assembly, checkout and an initial QSO with our KPA500.

The assembly of the kit was quite straightforward and I was able to complete it in about 5 hours. The amplifier worked fine after assembly. It  performs well on all of the Amateur Bands from 160m – 6m and delivers its rated output of 500 W with 25-35 watts of drive power. The initial QSO in the video was made using our Elecraft KX3 Transceiver which provides a maximum of 12 watts of drive power to the amplifier. As you can see in the video, the KPA500 produces about 200 w output using the KX3. I have also tested the KPA500 with a 100W transceiver and found that it produces the rated output on all of the bands and runs cool and quiet. Testing with my station monitor as well as on-air reports indicate that the KPA500 produces a clean signal.

I know that some of you may be wondering how I made the time-lapse video included in this post. I found a very good how-to webpage that explains how this is done and includes links to some good software choices to perform the various steps in the process. The software and hardware that I used are listed in the credits at the end of the video for those who are interested.

Time Lapse Video Setup

Time Lapse Video Setup

The basic setup requires a digital camera on a tripod that can take a series of still images at regular intervals. My video was created using a Nikon D7000 which took a still frame  every 5 seconds. The video required a total of about 3,900 individual photos to produce a 24 fps video that is about 2:40 minutes long. A combination of Batch Photo Editing (Adobe Lightroom), Time-Lapse Assembly, and Video Editing (Apple iMovie) tools were used to complete the project.

The plan is to couple the KPA500 with Anita’s new Flex-3000 Software Defined Radio (I got a not so subtle hint too). More on the Flex-3000 and its operation with the Elecraft KPA500 will be the topic of a future post.

– Fred (AB1OC)

Feedline Breakout System

Feedline Breakout System

Feedline Breakout System

Since Anita (AB1QB) and I both want to operate at the same time, we are planning to put two SteppIR DB36 Yagis on our tower. These antennas will be connected to a DX Engineering Stack Matching System so that they can be operated together as a 4 over 4 array. The DXE Stack Match can select either antenna individually and connect it to the feedline associated with the array but it does not provide breakout of both antennas onto separate feedlines. We designed and built a custom feedline breakout system to enable simultaneous breakout of both antennas to separate feedlines. This project involved the construction of both a tower mounted box to house a part of relays and a control box for the shack.

This device is inserted between the Stack Match and the antennas in line with the two phasing lines to each Yagi. It is critical that the breakout device provide identical impedance and phasing effects on both phasing lines if the array is to function correctly. To accomplish this, we selected a pair of Tohtsu Coaxial Relays (Model CX-800N) that have very low SWR impact in the HF bands. These were installed in an outdoor utility box that we got from DX Engineering. Only one relay is used to breakout the lower antenna to a separate feedline as the Stack Match can break out the upper antenna to the main feedline for the array. The reason that two relays are needed is to ensure that RF performance of both phasing lines to the two antennas is identical.

Coaxial Relay

Coaxial Relay

The relays require a 24V source to energize them. I built a simple control box for the shack to provide the needed control voltage. The controller includes three switches so that it can be used for additional 24V relay applications in the future.

Breakout Control Box

Breakout Control Box

I wanted to be sure that the Breakout System had good isolation characteristics between the two phasing lines so that the device did not allow a transmitter using one antenna to interfere or possibly damage a transceiver using the other antenna.. The relays we choose have good isolation characteristics which is a good start. To ensure that we have good isolation at a system level, I used an ArraySolutions Vector Network Analyzer (VNA) 2180 to measure the isolation between the various input and output connections in the Breakout System. The ArraySolutions VNA 2180 uses a PC and software to control a measurement unit which can perform one and two port SWR, impedance, loss and phase measurements (many other measurements are possible as well). In this case, we are making a port to port loss measurement.

Isolation Measurement Setup

Isolation Measurement Setup using a VNA

The VNA 2180 has a dynamic range of about 100 dB which means that it can measure isolation up to this level. As you can see from the following screen shot taken with the VNA software, the isolation of the Breakout System is very close to the limits that the VNA can measure. The worst case isolation measurement is about -97 dB on the 6m band. We also use Bandpass Filters when we are both operating and these filters provide an additional 55 dB or more of isolation which means we have a total of about 150 dB of isolation through this path. In the real world, the antennas themselves will likely have much less isolation between them than this so the isolation performance of the Breakout System should be more than adequate.

Isolation Measurement Results

Isolation Measurement Results

We are making good progress towards the planned installation of three of our Yagis on the tower next week. I will provide some additional posts over the next several days covering additional aspects of the preparation for next week.

– Fred (AB1OC)