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Propagation Forecast Bulletin #29 de K7RA:

from W1AW Bulletin via the ARRL on July 23, 2010
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Propagation Forecast Bulletin #29 de K7RA:

Propagation Forecast Bulletin 29 ARLP029
>From Tad Cook, K7RA
Seattle, WA July 23, 2010
To all radio amateurs

ARLP029 Propagation de K7RA

Sunspot activity increased recently, although it is foolish to call this a trend because solar activity has great variability. Sunspot group 1087 was visible for 13 days over July 9-21. In millionths of a solar hemisphere, its size was 30, 100, 120, 130, 70, 100, 60, 50, 20, 10, 10, 10, and 10. On July 19 new sunspot group 1089 appeared over the eastern horizon, with a relative size of 130, 150, 310 and 240 for July 19-22.

Predicted solar flux for July 23-25 is 88, 85 on July 26-30, and 83 on July 31. This is fairly strong, considering that the average daily solar flux for each of the past four weeks was 73.9, 72.8, 79.2 and 80.6. There is a small predicted rise in geomagnetic activity, with a predicted planetary A index from July 23-31 of 10, 10, 8, 8, 10, 7, 7, 5 and 5.

Geophysical Institute Prague predicts unsettled conditions on July 23, quiet to unsettled July 24, unsettled July 25-26, unsettled to active July 27, and unsettled July 28-29.

Perhaps another sign of a quiet sun, which includes a weakening solar wind, is the collapse of the Earth's thermosphere. Marcia Stockton, NU6N, who lives off the grid on a wilderness ranch northeast of Bakersfield, California at elevation 4,500 feet, shared with us an interesting article from NASA. Titled "A Puzzling Collapse of Earth's Upper Atmosphere", you can read it at

Kurt Kochendarfer, KE7KUS of Phoenix, Arizona sent in a report last week just a few hours late for bulletin ARLP028. He reports, "The evenings of 11 and 12 July I was working 20m PSK-31 around 14.070 and saw strong openings into central European Russia from my QTH in Phoenix, AZ which began around 0330Z and lasted approximately an hour on each night. With a minimal antenna setup (275 foot long horizontal loop mounted on top a block fence up about 6 feet) and 50W I worked UR8MH, UA3PT, RZ3DC, and RA3FO in a period of 20 minutes beginning at 0340Z on 11 July. Numerous other Russian and Ukrainian stations were heard, but I was unsuccessful breaking through the mini-pileups. This was a real treat, as I usually have a hard time working that far east in Europe with my antenna setup".

"I suspect the gray-line may have had something to do with the propagation, and it made for an enjoyable couple of hours to add some new European DX to the logbook. Summer evening DX on 20m has been relatively good here in Phoenix, of late as well. In the last month I've had success working FO8RZ in Tahiti, and heard a number of South Pacific stations from New Caledonia all the way to central Australia".

"While the solar numbers aren't anything remarkable, the relatively quiet conditions combined with my loop antenna have made for lots of new contacts in the logbook".

Thanks, Kurt. That low antenna sounds like a good NVIS aerial for 75-80 meters. NVIS, for those who don't know, stands for Near Vertical Incidence Skywave. The concept involves an antenna close to the ground with a high angle of radiation. That is supposed to provide better regional coverage on the low bands than a low-angle radiator does because the radiation going up refracts back to a more immediate area. Assuming that 1005 divided by MHz is a good formula for calculating dimensions of a full-wave loop, then the reciprocal suggests a frequency of 3.655 MHz.

Mike Majority, N4VBV of Sumter, South Carolina mentions that beacons on the ten meter band are useful for detecting openings, even when no live hams are on the air. His page at gives some beacon info and resources, and he suggests W5JO as a good source of data. W5JO has a beacon list for 10 meters at It is also worth mentioning the Northern California DX Foundation and their sophisticated networks of beacons on 20, 17, 15, 12 and 10 meters. See info on their web site at

Jim Fenstermaker, K9JF lives in the Ballard neighborhood in Seattle, but has a station in Vancouver, Washington (not to be confused with the VE7 Vancouver) near Portland, Oregon. He writes, "The opening on 20 on Saturday evening and Sunday morning was fantastic during the IARU Contest, the best I have seen for many years. By 0000Z on Saturday, I worked one (1) WRTC station and in the evening I was able to add another 37 or so. Overall, my low power entry totaled 953 Q's. I operated from the Vancouver QTH which allowed for the antennas to play and the neighbors to be spared from large amounts of RF in their stereos. But, all the locals worked stations over me as they were high power entries. I now have the view that both QRP and Low Power is not for sissies. And, I have not sat in the chair for 24 straight hours for years either".

Robert Elek, W3HKK of Johnstown, Ohio writes this about six meter signals last weekend: "During this weekend's VHF Test, I noticed numerous bursts of signals in the S-5 range, about a half syllable long, and then the signal was gone or just tickling the noise level at S1. It happened a few dozen times. Am I hearing meteor burst propagation or momentary ducting, or??"

"I also heard numerous weak signals from 100-500 miles out that would slowly build up to S2 (Q5) for a few minutes and then fade down into the noise. This happened over and over with the same station, typically around 8-10 am. What is the most likely cause of that?"

"Test conditions were punk with only a couple of signals from CO, TX, etc, and a few from around 300-400 miles out but very weak. Most were from Ohio about 50-150 miles away".

Don't forget to check the latest issue of WorldRadio magazine, free online on the twentieth of each month. Each issue has a propagation column from Carl Luetzelschwab, K9LA, and this month Carl also has an article noting the passing of Bob Brown, NM7M. Read it at In Carl's column in the current issue (August 2010) he reviews the N6BV Propagation Predictions.

If you would like to make a comment or have a tip for our readers, email the author at,

For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of the numbers used in this bulletin, see An archive of past propagation bulletins is at Find more good information and tutorials on propagation at

Monthly propagation charts between four USA regions and twelve overseas locations are at

Sunspot numbers for July 15 through 21 were 15, 17, 13, 12, 25, 32, and 38 with a mean of 21.7. 10.7 cm flux was 75.9, 76.6, 78.7, 76.9, 79.8, 87 and 89.1 with a mean of 80.6. Estimated planetary A indices were 10, 4, 2, 3, 4, 5 and 5 with a mean of 4.7. Estimated mid-latitude A indices were 10, 2, 1, 2, 2, 3 and 3 with a mean of 3.3.

Source: W1AW Bulletin via the ARRL.

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