U3B27 uses callsign VA3UAL on telemetry channel 4 30meters on minute 6 and 8 and 20meters on minute 0 and 2.
A box was constructed of pink foam and a layer of mylar film was placed on the interior walls.
The 150mah battery was wrapped in plastic and placed on top of the U3B radio. This combination was then wrapped in plastic film.
The box was 1/2 filled with Aerogel insulation and then the radio battery combination inserted about the middle.
Aerogel insulation was put above the radio battery combination then a top sheet of mylar film.
The intent was to use the heat from the radio to keep the battery warm after dark. Later iterations of the U3B will be able to turn on resistance heat as the temperature drops to increase battery warming.
Aerogel is supposed to increase it's insulation values as the atmosphere gets thinner. Wires for solar panel and switch and antenna were placed in tiny grooves in the top of the foam box. The lid containing 8 x 240ma solar cells was glued on top of the box. In flight the solar cell can completely charge the 150 mah battery in 2.5hrs from sunrise while running the transmitter so there is quite a bit of overcapacity on the solar cells and the next step would be to use a larger battery to try for 24hr transmissions. The exterior side walls were painted with a dark colour to hopefully get some thermal gain at sunrise and sunset. The clear balloons are stored flat between 2 sheets of thin plywood. The balloons are pre-stretched before flight. The U3B is transported to the launch site in a shoe box with the antenna rolls.