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.The Icom IC-7300Preparing 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.
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-WAPRS 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.Good test of WSPR signal from K4KNS!
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.
