Welcome to the Illawarra Amateur Radio Society
All enthusiasts of electronics and Amateur radio are welcome to attend our monthly meetings. We meet at the newly refurbished Coniston Community Hall on Bridge road.
We are next door to Coniston train station and meet at 7:30pm every month on the 2nd Tuesday of that month (Excluding January)
Your next IARS meeting is:
IARS 70th Anniversary Balloon Launch
CALL SIGN: VI2AMW70
Where: Good Hope Resort grounds outside YASS Latitude/longitude -34.9229 / 148.8058
Date and time: 1st July 2018, 07H00 to 08H00 weather permitting
Planned ascent and burst height: 7m/s, 25~30km (82000 ~ 100000ft)
Payload: CW transmitter, APRS transmitter and power systems
Balloon type: Latex 2m Helium filled. Filling to a lifting weight using a spring scale. Parachute to allow a descent of approx 5m/s.
APRS TRACKER
The APRS tracker consists of a 300mW RF module operating on 2m, APRS frequency. The antenna is a fixed single element dipole. The RF module input is connected to an Arduino module which has input from a GPS module. This setup will transmit the balloon ascent rate, GPS location, temperature and status. The Arduino module has analogue inputs for temperature and battery voltage. The transmission spacing’s are approx every 90seconds. The power requirements are 5VDC.
CW TRANSMITTER
The CW transmitter consists of a simple crystal oscillator at 28.636MHz that is fed via a buffer transistor with a impedance matching transformer to the output transistor. This will raise the power output to approximately 200mW. The output of the transistor is fed through a pie filter tuned for 28.636MHz. This is fed to the centre of a wire dipole antenna cut to length for the operating frequency. The crystal oscillator is turned on and off by a small Atmel MCU programmed to generate the call sign and information of the balloon, as well as real time temperature from a temperature sensor and battery voltage as status including health status of the two converters on board. As the temperature and battery voltage changes, the Morse code will tap this new information out at approx 14 words per minute. This cycle will be repeated with a 30 second delay of non-transmission. Power requirements is 5VDC.
BATTERY POWER SYSTEM
There are two sets of series Lithium sulphate batteries installed. Each string give 3VDC at 3Ah.
This allows a redundant backup system. The batteries are individually fed to separate DC to DC boost regulators which will maintain 5VDC for the electronics on board.
The outputs are individually fused with automatically resettable fuses. This maintains integrity for all controls and systems.
MOBILE IGATE
The mobile Igate has been implemented specifically for the recovery team, who will be using the APRS tracker information to locate the balloon when it lands. This important system will allow better coverage of the internet than standard systems. Once the recover team have an approximate location, the CW transmitter will continue to transmit even whilst the balloon is on the ground allowing DF equipment to be used. Test have concluded that even with the 10m dipole on the ground, the beacon could be heard 4 kms away.
Special callsign
We have been allocated a special callsign to mark this special time for the club. VI2AMW70. This callsign is available for use by club members to mark our 70th birthday.
Echo Link Net – Every Saturday Morning!
IARS will host an Echo Link Net every Saturday kicking off at 09:30hrs on VK2RMP on 146.850MHz. Why not jump on and join the conversion!
