AM broadcast band DXing with:
Antenna 1: 6-foot diagonal wooden-frame loop
Antenna 2: 23-foot “fishing rod” vertical with MFJ-1020C amplified pre-selector
Combiner: Quantum Phaser
Receiver: RTL-SDR dongle, Ham It Up upconverter into laptop
Two mornings previous, I picked up decent audio from HLAZ in South Korea. On the 22nd, there was a major opening to Asia, with HLAZ again, but also many other stations with audio or at least carriers.
The thing that makes this possible is that most of the rest of the world divvies up the AM broadcast band in 9 kHz steps, while North and South America use 10 kHz steps. Thus, one part of the world can hear stations from the other part in the interstices between their regular stations. The less landmass between you and the other continent the better, so in Arizona, trans-Pacific (TP) reception generally works better than trans-Atlantic. But, it also requires favorable ionospheric conditions and listening in the hours before sunrise. Thanks to some insomnia, I happened to be listening at the right time, and by all accounts this was one of the best TP openings this fall/winter.
I checked just before 4am and there wasn’t even a carrier at 1566 for HLAZ. However, when I went back at 6am (13UT) things were happening. I checked the low-end of the band several times, but didn’t see anything, so spent nearly all of my time on the high end. I ended up doing some audio recordings, and finally some wideband SDR recordings of the raw data up through just after the 7:34am (1434UT) sunrise when things finally settled down. The best signals were mostly around 10 minutes before sunrise. By that point, I realized that my vertical antenna and phaser weren’t helping and stopped using them. My tuned loop is broadband enough that I was able to get some interesting signals quite a distance away from the nominal ~1550 kHz setting. It’s difficult to look at every single frequency for every single minute, but here’s a sense of roughly what I was getting. Note that my tentative IDs for the stations are probably wrong in some cases, so don’t take them too seriously.
Tentative ID: 1332 JOSF, Nagoya Japan, 50kW; but again could be 100kW out of China
Weak carrier at times; see previous screenshot for 1314 kHz.
Tentative ID: 1422 JORF, Yokahama Japan, 50kW; there’s a 600kW station in China here, but probably too far inland
Produced some very weak audio around 1337UT and 1427UT and maybe other times. The audio from 1337UT isn’t much, but I’ve posted it anyway. You can hear just enough to tell that it’s a woman’s voice:
Tentative ID: Possibly China, but this has been reported as an NHK 2 affiliate out of Japan
Possible carrier at times, but you can see that there is a “birdie” at 1464.5 kHz, and my two local blowtorches are at 1450 and 1490, so this area is fraught with problems. This screenshot is at 1418UT.
Tentative ID: 1503 JOUK, Akita Japan, 10kW; that’s what gets reported on this frequency, my power reference might be wrong, there’s also a Taiwanese 600kW powerhouse on this freq
Fairly strong carrier and this one might have produced audio if it wasn’t right next to my 1kW local on 1490 just 1.2 miles away from me. Screenshot from 1426UT.
Tentative ID: 1521 China Radio Intl, Urumqi China, 500kW; however, this is far inland and the broadcast is supposed to be in Russian so the signal might not be at all pointed this way, my source shows nothing from Japan above 1kW
Medium carrier, but right next to domestic 1520 kHz. See previous screenshot.
Almost certain ID: 1566 HLAZ, Jeju Rep. Korea, 250kW
Had some decent audio at times and here is a recording from 1418-1420UT:
1575 and 1584 kHz
I’m lumping these together because while there may have been weak carriers at both frequencies, there was too much splatter from American and Mexican music on 1580 kHz to really see it well. The apparent carrier detections were based more on persistence than seeing something obvious. But, here is a rather uninspiring screenshot for 1430UT. The 1575 kHz signal would likely be the VOA out of Thailand.
Tentative ID: 1593 China National Radio 1, Changzhou China, 600kW; this ident is fairly secure although I couldn’t prove it from the audio alone.
Had occasional marginal audio, but there was also splatter from 1590 and 1600 kHz. The best audio was at around 1429UT. Note that the Chinese station is the deeper male and female voices buried below the static, while the squelchy male “Donald Duck” voice is splatter:
Tentative ID: My sources do not show anything powerful enough for this, so I’m not sure what to make of it.
This is really a microscopic carrier, but again there was considerable persistence in the face of the domestic signal on 1600. Screenshot for 1423UT:
Tentative ID: Australia dominates this frequency, but at low power. Other people do report this as Australia, but my loop was pointed 90 degrees from there, so I’m sure what I might have picked up.
Medium carrier at times, screenshot for 1418UT: