Register Account

Login Help


US-to-VK Transpacific Reception on 630 Meters Reported


A radio amateur and medium-frequency (MF) experimenter in Australia has received a 630 meter (475.62 kHz) transmission from a radio amateur and Part 5 Experimental operator in Texas. While the approximately 8710 miles covered is not a distance record nor a “first” for that part of the spectrum, it does represent the sorts of accomplishments that the Amateur Radio community in the US might come to enjoy if a band at 472-479 kHz ever becomes a reality. John Langridge, KB5NJD, in Texas, who holds Experimental license WG2XIQ, told ARRL that having his WSPR signal heard in Australia on August 25 at 0952 UTC by David Isele, VK2DDI, was a “huge surprise.”

“I did not know until I got a text message that morning,” Langridge said. “I am normally checking the band during the overnight hours but went to bed very early on Sunday night and slept until almost 7:45 AM local. I had not seen my e-mails, but the local community as well as the one in Oceania was abuzz. Needless to say I woke up very fast and started looking at data.”

Langridge said he only recently renewed his FCC Part 5 license, requesting a power increase to 10 W in the process. He said the only longer WSPR reception report on 630 meters was in February 2013 and involved a 10,450 mile path from Australia to France. Signals from North America have been heard in Australia on 630 meters using other modes.

“Many of us use WSPR as an effective means of determining band conditions very quickly, which can lead to two-way [communication],” Langridge said. “WSPR has a very well-established listener base, which provides tremendous amounts of data with a 2-minute transmit cycle.” He said WSPR is a good tool to introduce newcomers to 630 meters and MF operation, and that many MF operators, including him, stumbled into the nether ranges of the spectrum by way of monitoring WSPR and, as he put it, “seeing how amazing this band really can be.”

WG2XIQ is equipped with an 80 foot tall asymmetrical T-top vertical, base loaded with a motorized variometer and almost 3 miles of radials. He generates a signal on 630 meters using an MF Solutions transmit downconverter, driving two GW3UEP Class D/E amps in parallel, combining them using a 0° hybrid combiner and filter with a low-pass filter. “I can make 200 W total power output, which at this time of year equates to about 4 or 5 W ERP,” Langridge said. “During the fall and winter, once the trees have lost their leaves and system resistance goes down, that 200 W TPO will look more like 10 W ERP, so things only stand to get better as we move into the 2014 MF season.”

On the Australian end, VK2DDI, who lives in New South Wales, said he was just taking “a quick look on 630 meters” when “up popped WG2XIQ” in a faint trace on his display. He was expecting it to be another Australian operator. “Pleasant surprise for all concerned,” he said in a post to a 630 meter news group.

Isele uses a 30 meter thin, galvanized-iron vertical wire, strung between a ground rod and a high tree branch for receiving on 630 meters. It has no radials and no antenna tuner. “I hear better than most on most bands,” he told Langridge, adding that he lives in a rural area 512 meters above sea level with few noise issues.

“There are so many misconceptions about what goes on below the AM broadcast band,” Langridge told ARRL. “It’s amazing how many people still know nothing about the 630 meter band.” The ARRL is sponsoring the WD2XSH experimental group in the vicinity of 500 kHz.





Instragram     Facebook     Twitter     YouTube     LinkedIn