HamBONE-04A

"Micro-beacon" test flight

You might call this flight a "return to the good old days" of expendable lightweight payloads. But this time, we are pushing the lightweight aspect of the design, minimizing weight wherever possible. The balloon was launched from a school about 30 miles south of my home QTH, by a 6th grade class currently studying meteorology. I was not present at the launch, but copied the CW telemetry from home and fed the results to the classroom through a network connection.

UPDATE 02/06/2004: The lithium "coin cells" I had planned to use turned out to be too weak for the task. They have a rated capacity of 110 mAh, and the beacon draws less than 20 mA, but the internal resistance of the cells drops them down to about half voltage at this load -- meaning no voltage regulation. So I had to fall back on the tried and true "Ultralife" lithium 9V battery, adding a lot of weight. This should still come in as the lightest ham payload with telemetry capability.

UPDATE 02/09/2004 2030Z: The launch went smoothly despite fairly strong surface winds. The balloon was released at 1955Z, five minutes ahead of schedule, since there was a lull in the wind and all systems were ready. Telemetry was nominal for almost 28 minutes, at which time the outside air temperature of -32C indicated an altitude of 23,000 feet. Then the signal abruptly stopped. Battery voltage was holding up fine so that was not the problem. My initial theory is that a solder connection in the beacon cracked with the low temperature, or one of the components got too cold; however, we may never know the real cause of the failure.

The payload package included:

lithium "Ultralife" 9V battery providing system power

8-bit microcontroller (PIC 12F675 SO-8)

outside temperature sensor (DS1721S)

battery voltage sensor

CW Beacon on 28.636 MHz (clock oscillator)

Vertically polarized 10m antenna

The completed payload package

On the weighing scale

Angus readies the beacon

Final preparations...

Telemetry from launch site recording:

de ka2qpg/bln 04a f003 oat     06c bat 8r7v pse qsl AR
de ka2qpg/bln 04a f004 oat     04c bat 8r9v pse qsl AR
de ka2qpg/bln 04a f005 oat     02c bat 8r4v pse qsl AR
de ka2qpg/bln 04a f006 oat     00c bat 8r5v pse qsl AR
de ka2qpg/bln 04a f007 oat neg 01c bat 8r5v pse qsl AR
de ka2qpg/bln 04a f008 oat neg 02c bat 8r2v pse qsl AR
de ka2qpg/bln 04a f009 oat neg 04c bat 8r4v pse qsl AR
de ka2qpg/bln 04a f010 oat neg 03c bat 8r1v pse qsl AR
de ka2qpg/bln 04a f011 oat     00c bat 8r1v pse qsl AR
de ka2qpg/bln 04a f012 oat neg 02c bat 8r0v pse qsl AR
de ka2qpg/bln 04a f013 oat neg 03c bat 8r0v pse qsl AR
de ka2qpg/bln 04a f014 oat neg 04c bat 8r1v pse qsl AR
de ka2qpg/bln 04a f015 oat neg 05c bat 8r0v pse qsl AR
de ka2qpg/bln 04a f016 oat neg 06c bat 7r9v pse qsl AR
de ka2qpg/bln 04a f017 oat neg 08c bat 8r3v pse qsl AR
de ka2qpg/bln 04a f018 oat neg 10c bat 8r0v pse qsl AR
de ka2qpg/bln 04a f019 oat neg 13c bat 7r9v pse qsl AR
de ka2qpg/bln 04a f020 oat neg 15c bat 8r1v pse qsl AR
de ka2qpg/bln 04a f021 oat neg 18c bat 7r8v pse qsl AR
de ka2qpg/bln 04a f022 oat neg 20c bat 7r9v pse qsl AR
de ka2qpg/bln 04a f023 oat neg 22c bat 7r7v pse qsl AR
de ka2qpg/bln 04a f024 oat neg 24c bat 7r7v pse qsl AR
de ka2qpg/bln 04a f025 oat neg 26c bat 7r6v pse qsl AR
de ka2qpg/bln 04a f026 oat neg 28c bat 7r8v pse qsl AR
de ka2qpg/bln 04a f027 oat neg 30c bat 7r5v pse qsl AR
de ka2qpg/bln 04a f028 oat neg 32

Specs of the HamBONE-04A balloon:

Envelope: 300g latex sounding balloon inflated to 1.4 pounds free lift
Target rise rate: 1000 ft/min
Expected burst altitude: 90,000 feet
Downlink: 28.636 MHz CW, 50 mW "fireball"
Battery life expectancy: 40 hours

Telemetry format is as follows:

DE KA2QPG/BLN 04A F016 OAT NEG 20C BAT 8R2V PSE QSL AR

F 016 - Frame counter, increments on each data frame.
OAT NEG 20C - Outside air temperature, degrees Celcius.
BAT 8R2V - battery voltage in volts and tenths

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Page updated February 14, 2004