NCDXF/IARU Beacon Network

NCDXF/IARU Beacon Network

The NCDXF, in cooperation with the IARU, constructed and operates a worldwide network of high-frequency radio beacons on 14.100, 18.110, 21.150, 24.930, and 28.200 megaHertz. These beacons help both amateur and commercial high-frequency radio users assess the current condition of the ionosphere. The entire system is designed, built and operated by volunteers at no cost except for the actual price of hardware components, shipping costs, and so on.
Three articles about the beacons have appeared in QST within the past few years and these articles are now available online at the IARU web site at These articles have a lot of interesting details about the beacons. Most of the hardware used in the beacons is regular commercial equipment, but the controller is specially designed and is described in detail in Beacon Controller.
Stan Huntting, KW7KW, wrote, “There are at least two possible explanations for an apparently dead band: 1) propagation is poor, or 2) no one is transmitting. The NCDXF/IARU International Beacon Network addresses the second of these possibilities by insuring that reliable signals are always on the air, around the clock, from fixed locations worldwide.” With three minutes of listening for the beacons, one can find out either where a particular band is open or which band has the best propagation to a particular part of the world.
In principle, one can simply listen on the beacon frequencies and copy the CW callsigns of the various beacons to figure out where the band is open, but in practice, not every ham operator can copy calls at twenty-two words per minute and some beacons may be heard at too low a signal strength to catch the call. Because the beacons transmit at known times, it is easy to know which beacon one is hearing without actually copying the CW callsign. Since the beacons are running one hundred watts to a vertical, even a weak beacon signal may indicate a path with excellent propagation for stations using higher power and directive antennas.
In order to know which beacon is transmitting at any particular time, one can either refer to the Beacon Transmission Schedule or use your computer and one of the Programs to Help Beacon Listeners. If you want to know where to point your antenna or decide which beacons are the most interesting to you, you can refer to the Beacon Locations. If you have a computer and a computer-compatible radio and would like a record of when various beacons can be heard at your QTH, you will want to learn about Automated Beacon Monitoring.
In time, we hope to have many automated receiving stations around the world which post a record of what beacons they have heard on the internet for all to use. Such a setup raises many interesting questions about how to effectively display such massive amounts of information.
If you like the beacons, we hope you will support those who provide Support for the Beacons and you will surely want to keep up with beacon developments by reading the latest Beacon News and the Early Beacon History. If you are bothered by interference from other stations when you listen to the beacons, you may want to read about Beacon Interference.

The Early History of the NCDXF/IARU Beacons

by John Troster, W6ISQ

Shortly after the formation of the Northern California DX Foundation (NCDXF) in October 1972, the newly formed Board of Directors decided that the organization should expand its horizons to include something of a scientific nature in which all amateurs, DXers and non-DXers alike, could participate. NCDXF support for DXpeditions and overseas operations would be a priority because DXers of the world would be the major contributors to the Foundation. But we hoped to do more than just send radios and DXpeditions and print QSL cards.
We consulted our Scientific Advisor, Dr. O.G. “Mike”. Villard, Jr., W6QYT, Professor of Electrical Engineering at Stanford University and Senior Research Scientist at Stanford Research Institute (now SRI International). Mike had an idea. He was concerned about the disappearance of fishing and other boats in Alaskan waters every year. He believed that if the circulation of the Arctic currents were better understood, searching rescue ships would have a clearer idea where to look, thus increasing the chance for finding small lost boats. To help solve this problem, Mike suggested the possibility that a floating beacon be dropped into these Alaskan currents. This could be tracked by amateurs around the world to monitor the drifting course of the beacons.
Mike had a friend with just such a drifting beacon which would transmit on 20 meters with 1 watt or 25 watts, and it was being tested in Washington, D.C. Mike arranged for his friend to turn on the beacon one Saturday morning, and we organized a listening group on 20 meters via the Northern California DX Club 2-meter network. The beacon was easily readable with 25 watts, and pretty good with just one watt. So even the 1-watt QRP transmission could be monitored and useful to amateurs some distance away.
There was One Big Problem with the drifting beacons: their cost of $25,000 each was about 25 times greater than NCDXF had in the treasury. In addition, the beacons were non-recoverable. The idea of a beacon remained appealing, however, and with further thought, the development of a series of relatively low-cost stationary beacons world-wide appeared possible. It would be much cheaper and would still work!
We set up a series of brown bag lunch meetings at SRI to explore possibilities. To do the heavy thinking, we recruited some of the fellows who had worked on Oscar I-IV: Chuck Towns, K6LFH, who was president of Project Oscar at the time; Lance Ginner; and Board Member Jim Maxwell, W6CF, who was always full of imagination and creative thoughts.
After a month or so of meetings, we agreed it would be possible to develop a world-wide beacon network. It would feature all beacons transmitting the same message, each about one minute in length, all on the same frequency, one after the other, and going around the world. At Mike’s suggestion, we also planned to step down the power output of the beacons in 10 dB steps, beginning at 100 watts. The beacon would come on the air with 100 watts, sign the beacon callsign, then step down to each of four power levels, 100, 10, 1, 0.1 watt, and finally back to 100 watts for the sign-off call. Each power level would last about 10 seconds before automatically switching to the next level.
All this planning and daydreaming was just fine, but who was going to design and build this thing? We turned to Chuck Towns and he looked deep into the engineering talent of Project Oscar and came up with an enthusiastic, knowledgeable designer and builder, Jim Ouimet, K6OPO.
One seemingly small matter had to be addressed now, but it was potentially the biggest hurdle. We would need an FCC license! So we wrote a letter to Mr. A. Prose Walker, W4BW, then Chief of the Amateur Branch of the FCC. We received a prompt answer from him saying, essentially, he thought this was a good idea. The plan showed the creative ingenuity that amateurs had used in creating Oscar-1. It was a program that would be for the benefit and interest of all amateurs world-wide, and thus of interest to the WARC-79 planners (he expressed this sentiment personally later). He invited us to join as a member of the WARC-79 group which was beginning to develop the amateur agenda for that important international conference. The NCDXF/IARU World-Wide Beacon Network owes its existence to the early encouragement of Mr. A. Prose Walker.
Attending WARC-79 meetings in Washington offered the all-important opportunity to discuss with the FCC Amateur Branch engineers what requirements we would have to meet before submitting the proper application for an unmanned, automatic beacon on 14 MHz. One requirement was that we submit a contour map showing the beacon location, as well as the location of all amateur station operators in the San Francisco Bay Area who would be monitoring the beacon 24 hours a day. This was a precaution in case the beacon drifted off frequency, the keying mechanism failed, or anything else went wrong (the map requirement was the same as for early 2-meter repeaters). A lot of Northern California DX Club members did not realize they were now expected to have a receiver on 14.1 MHz day and night, and listen to it…continuously!
Meanwhile, back in Palo Alto, CA, Jim Ouimet was busy designing and building the beacon. He became so busy at work that he had to turn beacon construction over to a colleague. But the work proceeded and, on bench tests, did exactly what it was supposed to do.
The license arrived and we were assigned the call WB6ZNL, not exactly a nice, crisp, short beacon-type call, but it was a license and we were elated and grateful!
In 1979, the beacon was put in operation from a trailer on a low hill overlooking the Stanford University campus. It worked remarkably well, transmitting a one-minute message every 10 minutes for about two years. We received reports from all over the world telling of its reception. So the beacon was doing what it was supposed to do.
Now all we needed was to build eight or nine beacons and distribute them around the world. But there was another problem. Our beacon transmitter was very complicated to build and, we had to admit it, a real boat anchor. Also, Jim Ouimet was being sent world-wide by his company for extended periods. We definitely had a problem in manufacturing those other beacons.
About this time, Dave Leeson, W6QHS, came on the Board of Directors of NCDXF. We described the problem to Dave and he went to work in his lab. He came up with a solution: use a Kenwood TS-120 as the beacon transmitter and build a black box to control the entire system. Dave built the control unit and hooked it up to the TS-120 and, Voila!, we had a beacon transmitter that an amateur with an average build and strength could lift.
We now needed eight more beacons. Who was going to build them? Fortunately, the late Cam Pierce, K6RU, another NCDXF Board Member, took on the project with great enthusiasm. He had the control circuit boards designed and built, cabinets designed and made, cables fabricated, and the units tested. He turned on a real engineering production line.
The new beacons worked beautifully. We put up two quad loops at right angles, complete with a phasing box, designed by Mike Stahl, K6MYC, then at KLM Electronics. At about the same time, we received the call W6WX/B for the beacon. NCDXF had acquired the call after the untimely death of a well-known local DXer, Dave Baker, W6WX. That beacon was on the air almost continuously until 1990, when it was stolen from the trailer!
As Cam Pierce was building beacons, we began to contact potential beacon station operators spaced around the world. At the United Nations, we talked to Dr. Max de Hensler, HB9RS, “Mr. U.N. Amateur Radio.” Max immediately said yes, he would like to operate a beacon there. Martti Laine, OH2BH, arranged for a beacon at the University of Helsinki and also in Madeira. Local DX Club friend Bruno Bienenfeld, AA6AD, introduced us to an astronomy professor, Dr. Ahron Slonim, 4X4FQ, at his alma mater, Tel Aviv University. Kan Mizoguchi, JA1BK, introduced the beacon idea to the JARL. We also contacted old DX friend ZS6DN for a good location in the Southern Hemisphere. And at Honolulu City College, we spoke with Professor Bob Jones, KH6O. Later we received approval from Radio Club Argentina to put a beacon in Buenos Aires. Here were eight groups ready to operate a beacon and join W6WX/B at Stanford to complete the first World-Wide Beacon Network.
These new beacons were unique. Each would transmit the same one-minute message in sequence one after the other on 14.1 MHz. The message was the same as before: callsign at 100 watts, then four 9-second dashes at power levels descending from 100 watts to 10 watts, to 1 watt, to 0.1 watt, then back to 100 watts to sign-off. This same message has been transmitted on 14.1 MHz by beacons for almost 14 years.
Beacons were distributed to the operators as they were completed and tested. They have all been in almost continuous operation since being put on the air. We have had two thefts, one at W6WX/B, the other at JA2IGY. Lightning struck a tree which crashed into the antenna at ZS6DN/B. A hurricane flattened the vertical at KH6O/B. Once in a great while something did go wrong with the beacon or power supply, but was repaired locally. But the TS-120s, in general, were remarkably free of problems. This is a very good record, considering that they were on the air continuously for between 10 to 12 years each.
The International Amateur Radio Union (IARU) had been interested in beacons on a world-wide basis for many years. In 1984, at an IARU Advisory Council meeting, Alberto Shaio, HK3DEU, then Secretary of Region 2 of IARU, had an idea. He suggested that a frequency and time-sharing network, as used in the NCDXF system, would be the best way to present beacons on a world-wide basis. We talked it over and have been working together ever since.
Somewhat later, it was decided that the network should be expanded and up-graded to a multiband network. Also, we had ideas about expanding the number of beacons. But back to the old problem — who would do the work?
Quite fortuitously, at a meeting of the Northern California Contest Club in 1988, this writer met Bob Fabry, N6EK, retired Professor of Computer Science at the University of California, Berkeley. Somehow we drifted into a conversation about beacons and Bob said he would be interested in building rather than programming for a while. I suggested he talk to Dave Leeson, W6QHS, who designed the present generation of beacons, and who just happened to be sitting at the next table. They immediately started drawing pictures on the table and closely collaborated over many months until Bob had a prototype. Thus was born the new generation of beacons.
We wanted to shorten the time of each beacon’s transmission so we could increase the number of beacons without stretching listening time beyond listener attention span. So, Bob recorded beacon messages at various speeds, from about 10 to 20 seconds; that is, beacon call, then four short, power-stepping dashes only. He played the tape for the Directors of NCDXF, and we voted unanimously that 12 seconds would be about right. The same tape was played for a meeting of the Executive Committee of IARU Region 2. They agreed that 12-15 seconds was good. However, as a practical matter, Bob used a 10 second transmission for each beacon. This allows six beacons per minute, or 18 per three minutes, which is the number of beacons we wished to use.
Originally it was planned to use the Kenwood TS-140 transceiver for the beacon transmitter. However, various technical factors pointed to the Kenwood TS-50 as the better transmitter to use. It should be stated that Kenwood Corporation donated 16 of these transceivers to the International Beacon Project, for which we are sincerely grateful. Kenwood requested that a plaque be affixed to each TS-50 that states that the unit is dedicated to the memory of Jim Rafferty, N6RJ.
Bob constructed a control unit to control the functions of bandswitching and power stepping the beacon. He also used the Trimble Global Positioning System (GPS) receiver as a time control unit to assure accurate functions. Everything’s state-of-the-art in this new system.
As this new beacon was being crafted, we went to work with the IARU, with their worldwide associations, to secure additional beacon locations, principally in the Southern Hemisphere. As I write this in September 1996, Radio Club of Kenya, Radio Club Peruano, Radio Club Venezuelano, Radio Amateurs of Canada, New Zealand Amateur Radio Transmitters, Wireless Institute of Australia, Chinese Radio Sports Association, and Radio Club of Sri Lanka have accepted our invitation to join the network. One location is being held for Central Russia. These additions will bring the total number of beacons in the network to 18.
Frequencies were chosen for the five new bands after a survey of several months by Bob Knowles, ZL1BAD, and his worldwide crew at the IARU Monitoring Service. Frequencies chosen were 14.100, 18.110, 21.150, 24930, and 28.200 MHz. We are quite aware that 14.100 MHz is in the middle of packet station QRM. However, W6WX is limited to that frequency because of our FCC license. Actually 14.100 has been designated on the IARU band plan as a guarded frequency for the beacon network for many years. We are hopeful that packeteers will give a little up and down to keep 14.100 clear for the network.
Distribution of the new five-band beacons began in the fall of 1995. As of September 1, 1996, twelve of the 18 systems have been built and shipped. Six of the units are on the air and easily copiable. When the entire network is operational, a listener will be able to hear beacons from all parts of the world on a given frequency in a three-minute period. Alternatively, the listener can follow a single beacon through the bands and determine the best band open to that area.
We are grateful to the Universities, National Societies, and individuals who have volunteered to operate the beacons in this expanded network. It will be interesting to monitor the beacons during the increase in HF band activity as the sunspot cycle passes through its minimum and begins its climb back to DX glory!
(Reference: The NCDXF/IARU International Beacon Project, by John Troster, W6ISQ, and Robert Fabry, N6EK, QST, October and November 1994).

NCDXF/IARU Beacon Locations


DX Entity
Grid Sq
1 United Nations 4U1UN New York City 40° 45′ N 73° 58′ W FN3Øas
2 Canada VE8AT Eureka, Nunavut 79° 59′ N 85° 57′ W EQ79ax
3 United States W6WX Mt. Umunhum 37° 09′ N 121° 54′ W CM97bd
4 Hawaii KH6WO Laie 21° 38′ N 157° 55′ W BL11ap
5 New Zealand ZL6B Masterton 41° 03′ S 175° 36′ E RE78tw
6 Australia VK6RBP Rolystone 32° 06′ S 116° 03′ E OF87av
7 Japan JA2IGY Mt. Asama 34° 27′ N 136° 47′ E PM84jk
8 Russia RR9O Novosibirsk 54° 59′ N 82° 54′ E NO14kx
9 Hong Kong VR2B Hong Kong 22° 16′ N 114° 09′ E OL72bg
10 Sri Lanka 4S7B Colombo 6° 6′ N 80° 13′ E NJ06cc
11 South Africa ZS6DN Pretoria 25° 54′ 18.28″ S 28° 15′ 51.86″ E KG44dc
12 Kenya 5Z4B Kariobangi 1° 15′ S 36° 53′ E KI88ks
13 Israel 4X6TU Tel Aviv 32° 03′ N 34° 46′ E KM72jb
14 Finland OH2B Lohja 60° 19′ N 24° 50′ E KP2Ø
15 Madeira CS3B Santo da Serra 32° 43′ N 16° 48′ W IM12or
16 Argentina LU4AA Buenos Aires 34° 37′ S 58° 21′ W GFØ5tj
17 Peru OA4B Lima 12° 04′ S 76° 57′ W FH17mw
18 Venezuela YV5B Caracas 10° 25′ N 66° 51′ W FK6Ønj

NCDXF/IARU Beacon Transmission Schedule

Each beacon transmits every three minutes, day and night. This table gives the minute and second of the start of the first transmission within the hour for each beacon on each frequency. A transmission consists of the callsign of the beacon sent at 22 words per minute followed by four one-second dashes. The callsign and the first dash are sent at 100 watts. The remaining dashes are sent at 10 watts, 1 watt and 100 milliwatts.
Search the DX Summit Database for recent reception reports by callsign.
If you can hear a beacon now, send a report to DX Summit.

Call   Location 14.100 18.110 21.150 24.930 28.200 Operator Status
4U1UN United Nations 00:00 00:10 00:20 00:30 00:40 UNRC OFF3
VE8AT Canada 00:10 00:20 00:30 00:40 00:50 RAC/NARC OK1
W6WX United States 00:20 00:30 00:40 00:50 01:00 NCDXF OK
KH6WO Hawaii 00:30 00:40 00:50 01:00 01:10 KH6BYU OK
ZL6B New Zealand 00:40 00:50 01:00 01:10 01:20 NZART OK
VK6RBP Australia 00:50 01:00 01:10 01:20 01:30 WIA OFF4
JA2IGY Japan 01:00 01:10 01:20 01:30 01:40 JARL OK
RR9O Russia 01:10 01:20 01:30 01:40 01:50 SRR OK
VR2B Hong Kong 01:20 01:30 01:40 01:50 02:00 HARTS OK
4S7B Sri Lanka 01:30 01:40 01:50 02:00 02:10 RSSL OK
ZS6DN South Africa 01:40 01:50 02:00 02:10 02:20 ZS6DN OK
5Z4B Kenya 01:50 02:00 02:10 02:20 02:30 ARSK OFF5
4X6TU Israel 02:00 02:10 02:20 02:30 02:40 IARC OK
OH2B Finland 02:10 02:20 02:30 02:40 02:50 SRAL OK
CS3B Madeira 02:20 02:30 02:40 02:50 00:00 ARRM OK
LU4AA Argentina 02:30 02:40 02:50 00:00 00:10 RCA OFF4
OA4B Peru 02:40 02:50 00:00 00:10 00:20 RCP OK
YV5B Venezuela 02:50 00:00 00:10 00:20 00:30 RCV OFF6

1 – Operation may be intermittent due to local conditions.
2 – There is a problem with the antenna. The operators are working on it.
3 – Off during renovation work on the United Nations building roof.
4 – Off due to hardware failure. The operators are working on repairs.
5 – A lightning strike has caused damage. We are sending replacement hardware.
6 – The beacon hasn’t been heard for a while. We are contacting the operator