Launch date/time:

24 June 2001 - 0748 CDT (1248 UTC)

Launch site:

Treynor High School, Treynor IA

Payload frequencies:

Data  - 144.39 MHz (national APRS frequency)
Callsign N9XTN-11
Voice - 446.10 simplex repeater


AX.25 APRS-formatted location and telemetry, other raw text


600g Kaymont balloon

Maximum altitude:

83,625 ft

Payload weights:

6.0 lbs main capsule

Helium used:

190 cu ft (approx.)

Flight duration:

1 hour 58 minutes

Equipment manifest



Basic Stamp 2SX microcontroller
Kantronics KPC-3 v6.0 TNC (modem)
Alinco DJ-190T 2m handheld radio
Garmin GPS-35LVS GPS unit
Homemade J-pole antenna
Custom 7.2V 4000 mAh battery pack
Yaesu VX-1R dual-band mini handheld radio
Radio Shack simplex repeater

We had a successful, low-key launch from the parking lot of Treynor High School in Treynor, Iowa on Field Day Sunday.  At first there was just myself, Paul KC0KXR, and my fiancee Shari (now KC0KZK).  Some high clouds were overhead, but of greater concern were the winds.  They began increasing soon after dawn and were about 10 mph at launch time.  We arrived about 0715 and got everything in place to start filling in about 15 minutes.  Since the winds were continuing to increase, we decided to fill and launch immediately instead of waiting for the scheduled 0800 CDT.  We ended up about 12 minutes early, and I think did well with only three people on hand, some wind, and getting airborne about 30 minutes after arrival.  A grandfather/grandson pair arrived from nearby and watched us launch the balloon. 

Soon after launch we did get some traffic from the simplex repeater, however, we also heard some "ker-chunking" that seemed to be related to the APRS transmitter.  We launched one 6-lb capsule that had both telemetry and repeater equipment - normally they're in separate capsules.  We heard a few Field Day stations, but not as many as hoped.  

We chased south to Silver City which was not far away, and waited for the balloon to burst there.  The winds were very light and the balloon never went faster than 40 mph, making for a leisurely chase.  With the cloud cover we were unable to see the burst, which occurred at 83,625 ft about a mile south of Silver City.


After burst, we proceeded on to Malvern, expecting the landing to be southeast of there.  During that time we heard Steve N0ORU on the repeater and figured we'd all end up meeting at the landing site. We started to notice the simplex repeater audio was distorted, almost sounding like all the users had inhaled some of our helium.  The descent went faster than expected, so after initially going south of Malvern, we tracked back west and then north.  We met N0ORU on US34 and we all were in position about 0.3 miles away to watch the balloon land at 0946 CDT in a soybean field.  We made contact with the landowners and walked out to retrieve the payload.

No damage had occurred to the payload. The load line at the top of the parachute to the balloon partially fouled with the shroud lines - probably because it was too short.  The balloon shredded cleanly at burst and left only the neck and a few small shards attached.  The simplex repeater worked fine when tested later in the day, so I'm not sure of the source of the audio distortion.

Update: The distortion was likely due to weak batteries in the simplex repeater.  Later testing on other batteries showed that a weak set causes a similar distortion to that noted during the flight. We also found that 446.10 MHz is used by some terrestrial stations as a 9600-baud packet frequency - some of the noise heard was probably due to receiving the packet data.

Callsigns heard on the simplex repeater


(More stations probably made it, but my recording quality was too poor)