Transmitter hunt: NFARC pico-balloon

[VA7TD]

On Thursday Sept 7, Scott VA7SL called me via telephone, and said he needed my transmitter-hunting expertise.

He told me that the North Fraser Amateur Radio Club (NFARC) had launched a pico-balloon from Albion in Maple Ridge on Monday Sept 4. It was beaconing WSPR on 20m, with a power output of 20mW, powered by solar cells. It resembled a large elongated clear plastic bag.

After a series of successful launches, they had decided to experiment with this balloon. Filling a pico-balloon to capacity means when the gas expands at high elevations, the balloon will burst, so they only partially-filled this balloon in an attempt to allow it to gain a higher altitude. However, the partially-filled balloon didn't gain sufficient altitude, and it was only aloft for 2 hours before either going down or, more-likely, getting snagged by a tree on a high point. Scott said the GPS they had used wasn't overly accurate, and they were only able to locate it to the grid square (CN89 TE), which put it in the Silverdale area of Mission. The GPS figured it was at the 1100' elevation. It was only beaconing between 10:00am and 2:00pm, so it had a limited view of the sun. Scott said he wanted to meet up at the Silverdale Starbucks at 10:00am on Saturday. The day was supposed to be sunny, so we should be able to copy some solid signals. Coordination was to be on 146.5200 MHz.

I texted Lloyd VE7LGP, my old transmitter-hunt partner, to see if he was interested in coming out. Of course he said yes. Neither of us had a mobile or portable HF station prepared, so we quickly put something together with spare equipment. I had a TS-440SAT on the shelf, I dug out a Kenwood power cord equipped with PowerPoles, and wired up a PowerPole to cigarette-lighter plug adapter. Lloyd had a Comet UHV-6 mobile antenna with a 20m coil and a large mag-mount base, as well as a smaller 20m antenna for when we got very close, and a step attenuator. He installed WSJT-X onto his Toughbook.

I got up at 6:30am on Saturday morning, and headed out to Lloyd's. Lloyd tossed a drone into his SUV as a last-minute consideration. We proceeded to the rendezvous point in Silverdale. Neither of us had eaten breakfast, so we went into the Triple-O's and ordered Sunny Start's. I texted Scott to let him know we were at the Triple-O's, and he replied that he was just leaving his house.

Scott arrived in short order, and informed us that Dragos VA7MOV would be joining us later on with a drone. Scott then provided us with maps and area-info. According to the map, there are only 2 locations with that elevation in the direction of the balloon's flight-path on launch day, and Silverhill was the more-likely location. This was the first NFARC balloon that had continued to beacon after it had ceased flight. Interestingly, it was monitorable in Ontario and Hawaii from it's current location. Not bad for 20mW!

Lloyd and I set up our mobile station. The front seat of his SUV folds flat, so I sat in the back seat and used the flat front seat as a table for the radio and laptop. We took Lougheed Hwy west to Silvermere Lake, pulled over and and waited for the balloon to beacon. Our first reading was -18dB.

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Scott was unable to pull out a signal with his SDR and longwire setup.

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We left the highway, headed up Silverhill, and took some readings along the way. The signal improved to -9dB then -2dB. On a little loop road, we got +12dB and then +14dB. At that point, we pulled over to visually search the surrounding woods. On the return-side of the loop, we got +16dB, so we stopped for another search.

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Lloyd attempted to deploy his drone, but the batteries were dead (if he had thought about bringing it earlier, he would have charged the batteries). Scott headed down the hill to meet up with Dragos who was calling on VHF, while Lloyd and I relocated and attempted to get higher readings.

When Scott and Dragos arrived back to the loop, Lloyd and I had driven down a dirt road to get some readings and to visually search the trees. At one point, we spotted a shiny surface through the trees and up the hill, and informed Scott on VHF. Scott walked down the road towards us as we continued further down the road. At this point, the next beacon strength was lower, so we turned around and headed back towards Scott. Scott had the height advantage, and informed us that the shiny surface we had seen appeared to be the roof of a building.

Back at the loop road, Scott deployed his longwire setup again, and successfully received the beacon.

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Dragos deployed his drone. The idea was to search the trees from above, with sun behind it, which in theory would have the drone looking directly at the solar panels if it could see it. He a little difficulty getting a GPS lock, but got it into the air. He did not spot the balloon.

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While this was going on, Lloyd and I drove down the road a bit and waited for another beacon. This one was +18dB, our highest reading so far.

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We moved 10 feet forward, and got a +19dB reading. Moving further forward to where the road curved, we got a +16dB reading, so we moved back up to where we got the +19dB. At this location, with we noted that we had a hill on one side, and a valley on the other, with another hill after the valley, about 1km away. We wondered if maybe the balloon was actually on the next hill. Scott and Dragos had come down the road back to the vehicles, so we informed them that we were going to check out the next hill.

Of course, there was no direct route to the other hill, but we were eventually able to get to where we wanted to be. We took a few readings when the balloon was beaconing, and the signal was noticably lower over there (below 0dB). We informed Scott via VHF of our findings, noting that we were only about 1km away across the valley.

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At this point, we collectively concluded that the balloon was located near the loop, close to the location where we got the +19dB reading, and there wasn't a lot more we could do that day, with the limited road access in the area. Lloyd and I felt that we had gotten pretty close to the balloon, so we decided to charge the drone batteries and come back. Scott and Dragos headed for their respective homes. Lloyd and I went to his place, plugged the drone batteries into the charger, then went for lunch.

During lunch, we discussed how much fun we were having, and then the conversation turned to the equipment we were using. The TS-440SAT performed admirably as expected, but it was a little large for mobile/portable work. The UHV-6 worked well, although it was a little tall for the overgrown dirt road.

After lunch, we retrieved the batteries and headed back to the loop. Lloyd successfully deployed his drone, and spent about 45 minutes searching the terrain on both sides of the road and all around the top of the hill. Unfortunately, we were not able to locate the balloon.

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The next day (today, as I'm writing this), Adrian VE7NZ headed out to look for the balloon. Hopefully he'll find it!

Greg