PICO Facts


3rd Flight Taking Off

Testing Lift in Garage

Don Giles, KM5XK

Dean Shutt, AL7CR

PICO Balloon Project 

January 2, 2021

PICO Ballooning

In February, 2020, Don attended a ham radio TechFest produced by a local ham radio group, Rocky Mountain Ham Radio-New Mexico.  I say “group” because they are not really a club and instead are simply a group of people with common interests.  They have done some interesting projects and continue to innovate.  The TechFest was composed of 7 sessions about different topics and one that caught my eye was a virtual presentation by Bill Brown of Tennessee.  He has been active in PICO ballooning for a few years and is a recognized authority.  His presentation consisted of a Power Point explanation of PICO ballooning.

PICO means “small” and is used to differentiate a segment of ballooning that is not associated with high altitude or weather balloons.  Also, it is not related to hot air ballooning that most of us are familiar with.  PICO balloons are unmanned craft and barely weigh a couple of ounces.  The payload of these flights usually weighs less than 15 grams or about 1/2 oz.  The balloons are usually 36” Chinese Party balloons and can be purchased quite inexpensively on AliExpress.  Helium is the most popular gas fill for them but some folks are using hydrogen due to the shortage of helium in the U.S.   A  Chinese Party balloon will weigh about 35 grams.  So all together there is not much mass there.

The thing that makes this all possible is a world-wide ham radio tracking system called Weak Single Propagation Reporter or WSPR.  This network of ham radio stations listens for very low powered radio signals and report to some internet based web sites when they detect a signal.  The system was not set up for ballooning but lends itself to tracking balloons around the world quite well.  A PICO balloon carries a small low wattage transmitter and a tiny GPS unit.  As it travels with the air currents around the earth, the solar powered radio transmits its location, identification and power of the transmission.  The transmitters utilize small microchips that are programmed to convert the GPS location to a Maidenhead Grid Square.  The earth is divided into Grid Squares that measure 70 x 100 miles and each has a unique identification name.  It is the grid square location that is transmitted by the small transmitter.  The receiving web site assumes that the balloon is in the center of the grid square and places it there in the tracking database that it builds.  So, as the balloon travels, it is located and tracked by about 4 or 5 different websites which can be referenced by anyone with internet capability.  The owner of the flight cannot send commands to the balloon nor can it receive actual transmissions unless the conditions are just right.  WSPR has made PICO ballooning convenient for ham radio operators to get involved with.  Our radios are currently only transmitting about .010 watts (10 mW) on the 20 meter band at 14.095.60 mHz.  That is the recognized WSPR frequency.  You probably cannot hear us on this frequency but you can surely track our progress using the websites listed below.

My friend, Dean, and I have a weekly schedule when we meet on the airwaves and talk about common interests.  I mentioned the PICO ballooning technical session to him and we immediately set up a partnership between the two of us where we decided to get started in the ballooning effort.  Originally, we were going to launch our first attempts from Oregon but the Covid 19 problem shut down commercial flying and we then decided to split up the construction tasks and to finally launch from our location in New Mexico at 7,000’.  We have, so far, launched 3 flights with pretty good success.  However, the goal is to circumvent the earth at least once so our 4th flight will include some improvements that, hopefully, will make that happen. 

Our first flight ended up near Hudson’s Bay Canada after about 5 days.  The second flight crossed the USA, the Atlantic Ocean, France, Italy and then south across the Mediterranean Sea.  Then it crossed North Africa, the Middle East and we finally lost contact with it near the Iranian/Afghanistan border.  That 18 day flight was encouraging and created lots of interest.  The third flight included some modifications and it had weather problems near Texarkana, TX where we lost contact.  We are now constructing the fourth effort and are planning for the third week in January for a launch.  The sun will be making its way north and we will have more sunlight to power the little transmitter.  Due to weight restrictions we do not have any batteries on board and rely strictly on the solar panels for power.

Dean performs the mechanical/electrical part of the payload construction while I handle the balloon section.  He mails the completed transmitter/antenna package to me and I fit it to the balloon, fill the envelope with helium and when the weather cooperates we send it off.  Once we let go of the balloon we know that we will probably never see the equipment again and the tracking system will be our only contact with it.

There are not a great number of ham radio operators involved in PICO ballooning but there is a dynamic forum on the internet where we exchange ideas and relate our experiences with flights.  The experienced guys are more than happy to share their history and give advice to newbies about these projects.  There is lots to learn about altitudes, jet streams and weather in general.  We get very familiar with the weather websites.   


  1. Radio: Zach Tek Pico transmitter.  10 mW
  2. Antenna:  20 meter half wave dipole.  AWG 30 magnet wire with 6 pound fishing line.
  3. Power:  2 solar panels fastened to the transmitter.
  4. Total weight of payload: 13.6g.
  5. Balloon:  90 cm diameter Chinese Party Balloon.  35.5g.
  6. Gas:  Industrial helium.  99.9% pure.
  7. Flight 1, KM5XK-11.  New Mexico to Hudson’s Bay, Canada.
  8. Flight 2, KM5XK-12.  New Mexico to Iran/Afghanistan border.  18 days.  26,000’.
  9. Flight 3, KM5XK-13.  New Mexico to Texas/Louisiana border.  
  10. Flight 4, KM5XK-14.  Launch scheduled for third week in February, 2021.


If you want to track our progress you can use our callsign, KM5XK, with a 2 digit suffix like -11.  The suffix changes with each flight so I will advise of each one as necessary.

  1. Toma’s blog.  http://tt7hab.blogspot.com                                                           

     A very good, serious overview of PICO ballooning.  Tomas lived in Eastern Europe and recently passed away.  

2. WSPR Net tracking website:  http://wsprnet.org/drupal/wsprnet/map

    The main website for WSPR.org.

3. APRS.fi Tracking website:  https://aprs.fi/#!lat=35.47467&lng=-105.03400

    Website from Finland that tracks vehicles, boats, planes and others using     APRS.

4. VK7JJ Tracking website: http://wspr.vk7jj.com

    Australian website that plots paths of balloons, etc.

5. LU7AA Tracking website: 


    Terrific website from Argentina.  Originally an AMSAT centered site.

6. Zach Tek, a Swedish maker of low powered radios: 

https:  //www.zachtek.com

7. QRP Labs: https://www.qrp-labs.com

Makers of radio kits including PICO transmitters.