For Joe Craig, VO1NA, in Torbay, Newfoundland, things have been pretty exciting lately on VLF (very low frequency). He’s among the early MF, LF, and VLF experimenters in North America — active even before Canada allocated Amateur Radio bands in that part of the spectrum. He believes he accomplished a “first” for a Canadian radio amateur on October 22, when his very VLF, very QRP signal on 8.27 kHz (that would be the 36-kilometer band) was copied in the UK.
“After much effort on both sides of the pond, SWL Paul Nicholson in Todmorden finally copied a three-letter message,” he told ARRL. “It’s the lowest-frequency transatlantic message, made possible because of Paul’s EbNaut coherent BPSK mode and DL4YHF’s Spectrum Lab spectrum analyzer.” Even more amazing: The power was 10 µW ERP. Craig is permitted to run 10 mW by regulator ISED Canada (formerly Industry Canada). The transmission path was more than 3,500 kilometers (approximately 2,170 miles).
VLF signals have been copied across the Atlantic in the past. In March 2014, a very slow-speed (QRSS) CW signal on 29.499 kHz, transmitted by Bob Raide, W2ZM, a New York Experimental licensee, initially was detected in the UK by Nicholson. In June 2014, Dex McIntyre, W4DEX, in North Carolina, transmitted an EbNaut signal on 8.971 kHz, while running on the order of 150 µW effective radiated power. Nicholson detected that signal too. McIntyre needed no FCC license to transmit on 8.971 kHz, because the Commission has not designated any allocations below 9 kHz, dubbed “the Dreamers’ Band.”
Craig’s transmission from Newfoundland began at 2300 UTC on October 22 and ended 7 hours later. “Paul replied by e-mail the following day with the correct message,” Craig said, “and there was much rejoicing across the pond and in the Marconi Radio Club of Newfoundland!”
Craig said that Nicholson had detected a carrier from VO1NA this past spring, but it was not stable enough to send a message.
DL4YHF’s Spectrum Lab, with a GPS module output signal used to calibrate the computer and help from DF6NM and DK7FC, worked much better, Craig said. “Paul measured the phase for a few days before the message was sent. With the new high-stability carrier, Paul got me on the first call.”
The final stage of his VLF transmitter is what Craig described as “the very Canadian Traynor Group One/SC stage amplifier” from the 1970s. He says his is “the only known VLF transmitter in Newfoundland and Labrador.” His antenna, by the way, is approximately 100 meters (approximately 328 feet) of #12 copper wire, about 12 meters high on average.
Craig’s blog offers more information.