Ivan VK5HS Radio Sonde Hunt

It’s not often Radio Sondes travel as far as the Riverland, but on Friday evening Mr Balloon aka Mark VK5QI sent me a message advising the predictions looked good for us to maybe have a go at retrieving a Sonde. The seed was sown, I quickly hobbled a bit of kit together and prepared for the chase.

After a successful  first chase attempt along with Danny VK5DW on the Saturday morning flight I watched the Saturday evening flight hoping to learn more about the tracking program and flight information.

Observing the data as it was displayed on Habhub,  https://tracker.habhub.org, I took great interest in learning about the speed the balloon travels at and the varying temperatures, balloon height and other variables.

HabHubI watched the Adelaide area reporting stations data as the balloon drifted to the East and after a while the stations of VK5THB and VK5TRM started reporting the data. I also monitored the prediction software, comparing the accuracy of the program and the actual landing location.

The  balloon finally landed very close to the reporting station of VK5THB.  The last heard position of the balloon was at 51m and travelling at 31km/h and 88 degrees.

So with the data in mind I thought I might head out early Sunday morning to try and retrieve the equipment. With the data from the HabHub and APRS, https://aprs.fi, websites I then used google maps satellite view to look at the terrain the balloon had likely landed in. It looked to be cleared scrub land, so I made the decision… I will attempt an early Sunday morning  retrieval.

In preparing the necessary equipment for the retrieval, I mounted a quarter wave 402MHz vertical on the Cruiser roof attached to a Yaesu VX7 handheld. This was to alert me when I was getting close to the landing site. I loaded up my 70cm yagi along with a AOR8000 scanner set to USB, this was to be used while on foot to locate the Radio Sonde. I recorded the location info from HabHub  by means of a photo of the screen on my mobile.

OziExp2I then entered the last known position of Radio Sonde in to the OziExplorer software on my laptop. I also attached my GPS receiver so I could run the moving map function. I also entered the last known position on my hand held GPS unit.

Setting off at 0600hrs Sunday morning I headed of to the last known location. When I got within a couple of Km’s from the site I turned on my VX7 with external antenna attached so I could hear the transmitter. To my dismay… not a peep from the Sonde!  I then pulled up as close as I could to the last known position and put my direction finding gear together. Sweeping around in all directions, still no signals. I hadn’t thought about the battery life of the Sonde.

After a calming coffee and a bit of thought I grabbed my hand held GPS, 402MHz receiver with yagi attached  and started walking in the general direction of the Sondes plotted location. After about a 500m walk I was rewarded with a visual location of the silver radar reflector. I collected all Reflector and GPSthe equipment up and proceed back to the vehicle.

Lessons learnt from my 2 Sonde chases are:

  • Don’t rely on the internet when chasing balloons in remote areas where you may loose phone signals
  • Consider the battery life of the Sonde, I had been told it is approximately 6 hours
  • You do not need expensive tracking antenna’s, mine is home brew the plans are on the   https://rrc.org.au/2018/03/27/tech-night-march-2018/

This Sonde landed not far from Bob VK5FO’s receiving station so I sent Bob a quick early morning text message so he knew I was chasing this Sonde. I didn’t want either of us wasting our time, luckily for me I had it all to myself. Interestingly Bob has setup a site, http://vk5fo.com/553/wx-sonde, so you can enter planned chase. This is to advise other chasers you are out retrieving a particular Sonde so they don’t travel big distances to find the Sonde has been retrieved by another chaser.

Sonde and GPS

My plans for the recovered Sondes are to have them reprogrammed so they can be used for future Riverland Radio Club projects.

I would like to thank Mark VK5QI for all his work in the Sonde tracking programs. All the RX stations need a special mention, without them we wouldn’t be able to have accurate data to retrieve the Sondes. Rob VK5TRM tracked the first Sonde Danny VK5DW and I found down to approx. 150m and Bob VK5THB tracked the second Sonde down to 50m, this assisted in a speedy retrieval of both units.

As Mark VK5QI always mentions the bakeries on his chases, I stopped at the Waikerie Bakery to have a coffee and cake. Have to keep the tradition up, Hi Hi.

Thanks for reading,

Ivan VK5HS


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