May 2021 – N4MI Ham Radio

SOTABeams WSPRlite and ZachTek WSPR Desktop

WSPR (pronounced “whisper), which stands for “Weak Signal Propagation Reporter,” is a fantastic digital signal for assessing band conditions and evaluating antenna performance. It’s also great for detecting band openings. WSPR mode implements a protocol designed for probing potential propagation paths with low-power transmissions. The protocol was designed, and a program written initially, by Joe Taylor, K1JT. WSPR is included in the WSJT-X software, along with several other weak signal digital modes (FT8, FT4, etc.) for amateur radio. WSJT-X can be used to transmit and receive WSPR signals.

WSJT-X v.2.3.1 receiving and decoding WSPR on 20m.

There may be times when you don’t want to tie up your HF transceiver for WSPR signals, and you really don’t need the power that’s available in most HF transceivers for WSPR. With a decent antenna, you can transmit and decode signals over very long distances with very low power. Because of the encoding of the WSPR signal, a 200 mW signal has the same DX capability as a 1 KW SSB transmitter, or CW at 80W.

You can search the Internet for information on how to build your own transmitter, and there are also some kits for sale. There are also a couple of relatively inexpensive and small WSPR transmitters that are easy to configure and use. I have been using the WSPRlite Classic, made by SOTABEAMS, and two WSPR Desktop Transmitters, made by ZachTek. There are some common features between the two, but there are also quite a few differences. Both transmit a 200 mW signal using 5V (USB) input for power, and both use software for configuring your callsign, location, etc. They can also be powered from a USB power bank.

The WSPRlite and WSPR Desktop transmitter require 5V power and programming through a USB input (micro USB). Both have a SMA connector for the antenna, so a SMA male to PL-259 adapter may be useful for connecting to your antenna.

SOTABEAMS WSPRlite

The first WSPR transmitter I started using is the WSPRlite, which costs around $140. It is very small and light, and therefore great for portable operations. The unit contains internal filters for 20m and 30m, but SOTABEAMS also sells filter kits to expand the capability to include 630m, 160m, 80m, 60m, and 40m. I have not purchased or used any of the filter kits.

A unique feature from SOTABEAMS that comes with the WSPRlite is the DXplorer web site.

The WSPRlite instructions, configuration app, USB drivers, and firmware updates are available on DXplorer. Following the detailed instructions from the website, configuring the WSPRlite is a relatively easy process that involves installing USB drivers and configuration software, connecting to the computer through a USB port, selecting the appropriate COM port, entering data for a few settings, and saving the settings to the device. Once configured, the WSPRlite is ready to transmit. The trickiest part to begin transmitting is pressing a button 2 seconds after the start of an even numbered minute (i.e. 14:58:02, 10:20:02, etc.) to begin transmission. The time must be set accurately for the transmitted signals to be decoded.

Windows Device Manager will display the COM port. The WSPRlite is on COM14.

The WSPRlite configuration software is very easy to understand. Enter the callsign, Maidenhed grid locator, band, desired power level (5 mW – 200 mW). There is also a link to the DXplorer site to view statistical analysis of the WSPR signals you transmit.

The configuration application also provides a link to dxplorer.net, where you can view statistics and maps depicting the WSPR signals transmitted from the WSPRlite. There are several different ways to view the data, including a metric call DX10. According to SOTABEAMS:

We use the WSPR data to generate a special metric, DX10. We recalculate your DX10 range (km) every two minutes. DX10 is a great system performance indicator. The best HF system will give the longest DX10 ranges. … Within seconds of your two-minute WSPR transmit period ending, you can see where you have been heard.
https://www.sotabeams.co.uk/wsprlite-antenna-tester/

The main page for my callsign in DXplorer, with links to view maps, tables, and graphs. You can also change the band and callsign.

You will probably want to view the Spots Map first, for a visual representation of where your WSPR signal is being received. It is a zoomable Great Circle map centered on your QTH. WSPR only uses the first part of your locator so your exact QTH could be some tens of kilometers from your actual location. The map shows the location of stations that have received your signal over the selected period. The colors relate to signal levels. You can “mouse-over” the spots to see additional data.

The Spots Table provides more details about the stations that decoded your signal. It shows the raw WSPR data for your selected time period. This is useful as it allows you to see all the stations who spot you not just the DX10 list.

The DX10 table gives you a snapshot of your system performance. However it does more as it identifies the time ranges for the spots so that you can identify the best times for DX openings. At the bottom of the table is a “DX10 mean” for your 10 spots. If there are less than 10 spots the missing ones are assumed to have a range of 0 km.

For the DX10 graph, each data point is calculated from all your spots in the previous hour. The best 10 spots (in terms of range) are used to calculate a DX10 mean. The mean is displayed on a graph which is updated every 2 minutes. The DX10 graph gives a good indication of your system performance and band conditions. You can “mouse-over” the graph to see additional data.

The DXplorer website is where the WSPRlite really shines. It’s easy to use and provides lots of useful informaton.

WSPR Desktop Transmitter

The WSPR Desktop Transmitter from ZachTek also costs $140, and is slightly larger and heavier than the WSPRlite, but has several additional features. The unit includes a GPS receiver and antenna, which can automatically set the location (grid) and control the timing of the transmissions. Once initially configured, this makes operation nearly automatic. Additionally, the latest firmware and software supports Type 3 WSPR Messages. A Type 3 message can transmit a more exact location using six figure Maidenhead reports instead of the regular four figure report, which is especially useful if you use the transmitter in a mobile or portable application with it functioning as tracker.

I am using two transmitters, each designed for operation on different bands. The “Mid” model transmits on 40m, 30m, 20m and 17m. The “High” model transmits 15m, 12m, 10m and 6m.

Note: ZachTek now sells three updated models for this transmitter:
– “Low” for 2190m and 630m
– “Mid-Plus” for 160m, 80m, 40m, 30m, and 20m
– “High-Plus” for 17m,15m, 12m, 10m and 6m
You can purchase multiple units at a discount ($254 for a Mid-Plus and High Plus, or $359 for all three models).

WSPT Desktop Transmitter with the GPS antenna.

The WSPR Desktop Transmitter also uses an app for configuration. The documentation web page has links to the configuration software, a quick start guide, and lots of additional details about the transmitter. A USB driver might be required to connect to the computer, and there is a link on ZachTek’s download page. Similar to the WSPRlite, once the device connected to the computer with the micro USB cable, you can determine COM port using Windows Device Manager. You set the serial port (for my computer, COM13) on the Serial Port tab, and click open. After a moment the software will be connected to the device.

The Serial Port tab on the WSPR Transmitter Configuration application.

After the connection is open, the next tab to click is WSPR Beacon. This is where you will enter your callsign, and select the bands. With the GPS antenna connected and placed near a window, you should start seeing the GPS signal quality and a position lock. Once the position is locked, the Maidenhead grid information will fill in automatically. When initially powered up, it might take several minutes to start seeing the satellite positions and get a position lock.

Beacon configuration for the “Mid’ model, to transmit on 40m, 30m, 20m and 17m.

Beacon configuration for the “High” model, to transmit on 15m, 12m, 10m, and 6m.

Once the WSPR configuration is complete, click on the Save Settings button, then click on the Boot Configuration tab. In this tab, you can configure the transmitter to start up in WSPR beacon mode. When power is applied, once it achieves a GPS position lock, the unit will automatically start transmitting WSPR beacons, cycling through the bands that were set in the WSPR Beacon tab.

The Boot Configuration tab is for setting up the transmitter to automatically obtain a GPS lock and begin transmitting WSPR when it is powered up.

There is also a Signal Generator mode so the transmitter can be used as a piece of test equipment in your shack. It can output a 23dBm sine wave from 2kHz to 50MHz, depending on model. I have not tested or used this feature.

The WSPR Desktop Transmitter includes a Signal Generator mode

The WSPR Desktop Transmitter does not include access the DXplorer website like the WSPRlite, but you could still use DXplorer standard mode to view statistics for signals transmitted from either device. You can also view maps and data for WSPR signal on the WSPRnet.org website. You can get a free account to access all of the features on WSPRnet.

The Weak Signal Propagation Reporter Network is a group of amateur radio operators using K1JT’s MEPT_JT digital mode to probe radio frequency propagation conditions using very low power (QRP/QRPp) transmissions. The software is open source, and the data collected are available to the public through this site.
http://wsprnet.org/drupal/

The Map tab opens a configurable map for a visual representation of where your WSPR signals are being decoded.

Scroll down in the map to configure the view. There are several settings that you can use to tailor the information displayed on the map.

Map view configured to show spots for callsign N4MI on 30m over a period of 12 hours.

Click on the Database tab at the top of the web page to display a sorted list of spots. This view can also be configured.

The Database view can also be configured to filter the data and how the the details are presented.

Final Thoughts

The WSPRlite and WSPR Desktop Transmitter both performed very well. There are some difference in features and operation. For the price, the WSPR Desktop Transmitter offers a few more features and once configured it operates automatically every time it’s powered up. The WSPRlite is very small and easy to carry, and the DXplorer website offers excellent statistics for those tracking propagation conditions or comparing antennas. You can’t go wrong with either option, and your choice would depend upon your operating preferences.

Assembling a New HF Go-Box

This afternoon I finally got around to building a go-box for HF. I’ve had all of the components for a long time, but just never got around to the build. I would like to thank my friend Rusty, KG4HIR, who did most of the work on this build. This go-box is now ready to operate, but I hesitate to say it has been completed because there is still some empty space in the box to work with!

Here is a list of the primary materials used for this go-box:

Icom IC-7300
MFJ 4230MVP 30A Switching Power Supply with PowerPole Connectors
MFJ 939I Autotuner
Icom SP-35 External Speaker
West Mountain Radio Epic PWRgate
West Mountain Radio RIGrunner 4004 USB
Mounting Brackets for IC-7300 and Power Supply
Heavy Duty Hook and Loop Fastener Roll
Gator Case Molded 4U Rack Case
Two 1U Rack Mount Shelves
2U Rack Mount Panel Spacer with Venting
NEMA 5-15R Plug Adapter with Mounting Holes
3 ft. USB Cable B to B – F/M – Panel Mount USB Extension
M6 Terminal Binding Post
10 AWG Red/Black Zip Cord
45A Anderson PowerPole Connectors
RG-8X Coax Jumper Cables
UHF F-F Bulkhead Adapter
Heavy Duty Velcro Strips

This is not intended to be a step-by-step tutorial for the build, but we did capture lots of images to give you an idea of how the go-box was assembled.

Rusty, KG4HIR, did the hard work on this project! Here we have the materials gathered. We had mounting brackets for the radio and power supply, but not for the MFJ autotuner. Rusty is preparing to secure it with heavy duty hook and loop fastener strips.

The 4U rack mount case before installing the components.

More components used for the go-box: 10 gauge zip cord, zip ties, HF4 to PowerPole adapter, RIGrunner, and Epic PWRgate.

Preparing the hook and loop fasteners to secure the MFJ autotuner. In the future, we may create some brackets to secure it better, but the hook and loop fasteners are secure and very strong.

The MFJ autotuner and power supply attached to the top of the shelf. The mounting bracket for the IC-7300 is attached to the bottom side of the shelf.

The IC-7300 mounting bracket was secured to the bottom of the shelf that also holds the autotuner and power supply.

After looking at several configurations, we determined that mounting the PWRgate and RIGrunner upright would be more practical for adding and removing cables. They are secured to a piece of square aluminum tubing that is attached to the rack mount shelf at the back of the case.

All of the primary components are secured to the shelves inside the case.

For convenience, the primary connections into the go-box (AC power, ground terminal, USB cable to radio, and bulkhead connector for coax) are fitted to a vented panel spacer that is mounted at the top on the back of the case.

Beginning the process of making DC power and RF connections inside the go-box.

All of the connectors are attached to the vented panel spacer, and it is ready to be secured.

Completing all connections for power, tuner, USB, and coax.

The back of the (nearly) finished go-box. There is still some available space in the back and front of the case. Some of it will be left for airflow and ventilation, but we are considering whether some additional components could be added.

The front of the (nearly) finished go-box. You can see the external speaker and the open space at the center top and right side bottom shelf. We may put a meter in the top space, and create a storage compartment at the bottom.

I was told that a go-box is never really finished, and that there will be changes and additions. The Epic PWRgate in this go-box makes it very versatile. It can be powered by AC via the power supply, as well as by a battery and/or a solar panel.

This build took a little over four hours. Much of that time was spent measuring, aligning, drilling and cutting to attach the components to the shelves and spacer. I still need to add some ferrite beads on several wires and cables. The next step after that is a field test to ensure everything is working properly. (That will be a topic for another post.) Once the testing is complete and it is confirmed to be fully operational, I will use the go-box at club operating events and for casual operating from the tailgate or patio.

Balloon Launch with APRS & WSPR Tracker

On May 5th, I had the opportunity to participate as part of a team that launched and tracked two high-altitude balloons. This was part of an educational outreach with Savannah River Academy, a school in my community. Members from my club, the Amateur Radio Club of Columbia County (ARCCC), and two meteorologists from the National Weather Service assisted the school with the balloon launch. This was part of a series of activities with the school to teach students about radio, weather and space, in preparation for a ham radio contact later this year with an astronaut aboard the International Space Station! Savannah River Academy was one of only a handful of schools in the U.S. selected to contact the ISS through the Amateur Radio on the International Space Station (ARISS) program.

The balloon launches were covered by two local TV stations and the local newspaper:
Columbia County students launch weather balloon
Students at Savannah River Academy participate in weather balloon launch
Sky is NOT the limit: Radio club partners with Grovetown students for weather balloon launch
Weather balloon camera captures breathtaking views above CSRA

The first balloon, which carried a payload with a SPOT Trace GPS tracker and a GoPro camera, was designed climb to an altitude of 70,000 – 100, 000 feet before bursting and falling back to earth. A parachute was attached to the payload so it could return to ground intact for retrieval by a chase crew. We expected the payload to land approximately 50 miles east of the launch site, but the balloon traveled much farther than anticipated. The chase teams scrambled and the payload was successfully retrieved approximately 150 miles from the launch site. The camera captured some amazing images while the balloon was in the stratosphere. Some of the best pictures are featured in the linked news stories.

Photo captured from the high altitude weather balloon shortly after launch. This camera captured lots of amazing images during this balloon flight.

One of the many spectacular views captures by the camera on the high-altitude weather balloon.

This post focuses primarily on the second “pico” balloon, which carried only a LightAPRS-W APRS and WSPR tracker as the payload, and was designed to reach an altitude of approximately 50,000 – 60,000 feet and achieve neutral buoyancy to travel for a much longer period of time. The LightAPRS-W, which is very small, was powered by two small PowerFilm 4.8V solar panels with two 5F 3V supercapacitors. With this power source, the tracker transmits APRS on VHF at .5 to 1 Watt, and WSPR on HF at 10 mW (1/100th of a Watt!).

We spent several days configuring and testing the tracker, using the configuration and programming instructions provided by QRP Labs on GitHub, and following some helpful suggestions in the Tips & Tricks for Pico Balloons wiki. The tracker also had two light wire antennas for APRS (19.4 inches) and 20 meter WSPR (16.6 feet), and a counterpoise (16.6 feet) attached.

Assembled LightAPRS-W tracker with two PowerFilm solar panels and super capacitors. It’s really small and light!

Once assembled, the tracker was easy to configure with an Arduino IDE to load the APRS callsign (K4KNS-11), WSPR callsign (K4KNS), and a few other settings. It’s best to pay very close attention to the instructions and comments in the configuration file! After the loading the configuration, we placed the tracker in the sun to test and listen for APRS and WSPR signals. We were able to confirm that the tracker was transmitting good APRS and WSPR signals. Due to the very low power of the VHF and HF transmitters, we could only confirm local reception. With the tracker stationary and in full sunlight, we noted that the LightAPRS-W transmitted an APRS packet approximately every 5 minutes, and a WSPR signal every 4-6 minutes.

Assembled and configured LightAPRS-W in the sun to test the solar panels and monitor APRS and WSPR signals.

APRS received from the LightAPRS-W during testing.

It’s one thing to have a good test under controlled conditions, but quite another to achieve success under field conditions. On the day of the launch, the weather was marginal, but within acceptable parameters for a launch. We double checked to ensure the tracker was powered up and transmitting, and tied it to the balloon.

Good test of the APRS signal on launch day!

We had a good launch. The balloon, with the tracker hanging 16.6 feet below the balloon (to accommodate the counterpoise) and trailing a 16.6 foot HF antenna, quickly rose to an altitude above any potential obstructions and began its journey. Within moments, we saw the first APRS positions appear on aprs.fi. A few moments later, using the WSPR Watch iPad app, we saw that the WSPR signal was being received across the U.S.!

The first APRS track for balloon K4KNS-11!

The 10 mW WSPR signal was received as far west as Oregon!

It was all going so well! We continued to watch the balloon tracking eastward and climbing, following the same track as the high-altitude balloon that had been launched about a half hour earlier. Then, after about an hour of flight, both the APRS and WSPR signal went off the air. At that time the balloon was 55 miles east of the launch site at an altitude of 37,500 feet.

The track and final position received from K4KNS-11.

Location, speed, course, speed, altitude, temperature, pressure and solar cell voltage data from K4KNS-11 exported from aprs.fi.

We’re not sure exactly why the signals were lost, but we do not believe the balloon went down in that location. We are speculating that the tracker may have been damaged due to the high wind speeds on lost power. It is unknown how much farther the balloon might have traveled. Despite the relatively short flight, we did collect some good data for the students at Savannah River Academy to evaluate. We also proved to ourselves that we could successfully launch a balloon and track it with APRS, and that a very weak WSPR signal transmitted from high altitude could be received by stations thousands of miles away!

Map on WSPRnet.org showing stations that received the K4KNS WSPR signal on May 5, 2021.

Spot Database for K4KNS on on May 5, 2021 from WSPRnet.org.

Using aprs.fi’s data export tool, we were able to export a KMZ file with the balloon’s tracking data, and use Google Earth to view the full track and altitude changes.

Google Earth map of the track and altitude changes for pico balloon K4KNS-11 on May 5, 2021.

This was an amazing experience! We captured many lessons learned, and we intend to build another more hardened version of the tracker so we can launch another balloon and hopefully track it over a much longer distance and time.

Additional information about both balloon launches is posted to the Amateur Radio Club of Columbia County Facebook page.