9. Picoballoon Launch 6

   After the dissappointing results from the last balloon, we decided to respin the boards to try and fix this GPS self-interference problem. We also decided to add a low-pass filter to try and keep the WSPR transmitter harmonics out of the GPS band. The new boards did not arrive in time for the Memorial Day weekend, so we decided to launch anyways.

   After a day delay due to strong winds and high altitude clouds, we launched on the morning of Sunday May 30th 2021. The weather was beautiful. The launch party was Martin W6MRR, Robert K6RGG, and myself KF6ZEO. We launched again from the northwest corner of the Berkeley Marina.

   

   

   The winds were gusting to 5 knots or so, and ...

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10. Picoballoon Launch 5

    After the fourth launch, Martin W6MRR respun the tracker board to try and fix some GPS lock errors. Unfortunately, the new layout did not fix the self-interference, but we decided to launch the new tracker board anyways on Saturday May 22nd, 2021. The launch party was Rob NZ6J, Martin W6MRR, Robert K6RGG, and myself KF6ZEO.

    This time, Rob NZ6J brought a 20m receiver and speaker so we could actually verify the tracker was transmitting before letting it float away. While we didn't have any software to actually decode the packets, we were able to see that the transmitter on the radio S-meter. This is more of a nice-to-have, as the tracker board also has an LED that lights up when ...

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11. Picoballoon Launch 4

    The next Saturday after the third launch, Martin W6MRR, Robert K6RGG, and Rob NZ6J got together at the Berkeley Marina and launched another picoballoon. I was away on a much-needed vacation.

    Since the last launch didn't get above 9000 meters, Martin spent extra time measuring the payload and lift of the balloon. To go around the world, it's important that the balloon has enough lift to rise above weather that may push the balloon down, or coat it with water or ice.

    Here's the mass breakdown of this balloon, with the same tracker electronics as the previous launch:

    Item	Mass
    2 solar cells & carbon fiber stick	5 g
    Beacon PCB w/supercaps	7 g
    Upper wire	1.5 g
    Lower ...

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12. Picoballoon Launch 3

    On the morning of Saturday April 10, 2021, members of the San Francisco High Altitude Balloon group launched another picoballoon from the Berkeley Marina. Launch location was the south tip of Shorebird Park, and the launch party was Martin W6MRR, Robert K6RGG, Peter W6DEI, and myself.

    Balloon Hardware

    The hardware was very similar to the previous launch. The one big change this time was that the APRS 144.39 MHz transmitter was removed. This 500 mW transmitter took a lot of power, and sometimes RFI would lock the processor up bad enough that the balloon needed to power off completely before it would reset. The only transmitter on this balloon was WSPR on 14.0956 MHz.

    

    Output power of WSPR ...

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13. March 2021 Berkeley Picoballoon Launches

    As part of the San Francisco High Altitude Balloon group, Martin W6MRR has been experimenting with picoballoons. Picoballoons are different than regular amateur radio balloons in that are designed to be neutrally buoyant at around 40k feet. This requires payloads that are much lighter than traditional balloons, and different balloon materials that won't stretch or break. This altitude was picked because it is above airplanes and weather, but still in the jetstream, where they can float around the world in a matter of weeks. Our goal is to circumnavigate the globe at least once.

    Picoballoons use either Mylar or plastic material in their construction. More traditional Amateur radio balloons, like from our previous launch use latex, which expand dramatically at ...

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14. High-Altitude Balloon Launch from Davis

    The SF-HAB group got together in the beginning of August to do another high-altitude balloon launch. The purpose was to test out a new 3D GoPro camera to see how well it would perform at altitude. We also had a LoRA transciever onboard, which we are thinking about using as a remote cutdown device that we would fly on future launches.

    The jet stream in July was really unsettled, so we delayed for a few weeks while the winds picked up a bit and shifted heading. Watching the predictions from HABHUB gave us a good idea when to launch. This was one of our predictions before launch.

    

    Unfortunately, I really goofed up when doing the launch predictions. As you can ...

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15. High-Altitude Balloon Launch from the Berkeley Marina

    After the success of the KD4STH launch in September, we decided to do it again! A new group formed for San Francisco High Altitude Balloons (SF-HAB), and we started scheming. The hardware and time stars finally aligned on Sunday March 8th, and we decided to launch from the Berkeley Marina. Unbeknownst to us, this was only a few days before the whole world shut down due to COVID-19. Great timing!

    

    

    The balloon was a Kaymont 3kg balloon, and we used an entire K-sized tank of hydrogen for lift. Unlike some previous launches, we didn't use weights to carefully measure/specify the ascent rate, we just used the whole tank. During the chase, we calculated our ascent rate at about 1400 ...

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