The K7RA Solar Update
Sunspot numbers seemed to be in a free-fall this week: The average daily sunspot numbers declined more than 29 points to 87, while the average daily solar flux fell 6.2 points to 126.2. Sunspot numbers for June 14-20 were 114, 113, 110, 96, 66, 64 and 46, with a mean of 87. The 10.7 cm flux was 148.6, 144.9, 134.5, 124, 118, 109.9 and 103.7, with a mean of 126.2. The estimated planetary A indices were 4, 4, 19, 39, 15, 3 and 4, with a mean of 12.6. The estimated mid-latitude A indices were 4, 4, 19, 36, 13, 5 and 4, with a mean of 12.1
The outlook for Field Day weekend -- June 22-23 -- is for low sunspot numbers and quiet geomagnetic conditions. The progression of daily sunspot numbers in the past five days (June 17-21) was 96, 66, 64, 29 and 13. The predicted daily solar flux is just 95 for June 22-29, 125 on June 30-July 7, then 130, 135 and 140 on July 8-10, and then rising to 145 on July 11-12. The predicted planetary A index is 5 on June 22-29, then 8 on June 30, 15 on July 1-3, 8 on July 4-5, 5 on July 6-7, 8 on July 8-9, and back down to 5 on July 10-14
The solar flux forecast improved slightly from June 20-21. On June 20, a flux value of 90 was predicted for June 21-28. Then the next day, June 21, the predicted solar flux was changed to 95, predicted for June 22-29. The sunspot number at 13 on June 21 was the lowest since August 15, 2011. On the same day the solar flux dropped to 98 -- the lowest value since April 13, 2012, 10 weeks ago today.
OK1MGW sent a geomagnetic forecast for July 22-July 9. Mostly quiet, June 22-23, quiet to unsettled, June 24-29, quiet to active June 30, active on July 1-3, quiet to unsettled July 4-7 and quiet to active on July 8-9.
Jim Williams, K5NN, of Wichita, Kansas, wrote in response to last week’s Solar Update: “Some of the comments on the 1950s 10 meter propagation were interesting. I was first licensed as a teenager in 1952. My first equipment was a Command receiver/transmitter, so I could only get on 80 and 40 meter CW. In 1953, I built a 6L6 Heising modulated rig that could run 6 W on 10 meters. I was using a borrowed Hallicrafters S20R receiver with a pre-amp. The antenna was a ground plane made out of military surplus steel rod. I worked the world! I forget my country total, but it was well over 100 by the time I graduated from high school and joined the Air Force. I was not able to return to ham radio till the mid 1960s and 10 meters was still very good then. At that time, I was able to run many scheduled phone patches from Antarctica and the Military installations in the Pacific on 10 meters into West Texas and New Mexico.”
The Command set that Jim mentioned refers to a huge number of radios available on the surplus market for next-to-nothing after World War II. With a little modification, these could be put on the air. If you look in old copies of QST in the 1940s and 1950s, there were many conversion articles based around these radios. I even recall seeing one which converted a Command set transmitter to SSB, which involved gutting the unit and using a few key components. Find an article on these radios, with nice photos at the bottom here. Also check this photo, which I think might be of surplus radios ready to be dumped in the ocean after WWII. There were just too many to haul back to the United States. At this same site, check for many more photos of military radios from that era.
Rob Gregory, KD7H, wrote about Fidalgo Island, also mentioned in last week’s Solar Update. Actually, I noticed that W7LTQ is in Anacortes, Washington, which is separated from the mainland by a very narrow channel. When you drive there, it is not obvious that you are on an island. Rob wrote: “I am a big IOTA fan and I wanted to give you a correction, regarding W7LTQ’s QTH. Fidalgo hasn’t qualified as being part of IOTA NA-065 for quite some time because it doesn’t meet the ‘distance from shore’ requirement (it’s too close to the mainland, of course). The same holds true for Anderson, Camano, Fox and McNeil islands. Regarding propagation, this past week I couldn’t get to sleep, so I was on HF between 1 and 2 AM, and I was very surprised to be able to work into Europe -- including the United Kingdom -- on 20 and 17 meters (both CW and SSB), with New Zealand, Australia and Japan coming through at the same time. I was running about 400 W, but only using a G5RV up about 30 feet in fir trees alongside the house. Oddly, during the daylight hours, the bands seemed pretty dead in my neighborhood. But yesterday (Friday, June 15), OD5NJ had quite an amazing signal on 17 meter CW in the late afternoon and it was well past dark at his house. If I can hear good DX on my wire, then I can determine that the bands are open. At our latitude, that hasn’t happened much since last October. Thankfully, the DX gods smiled.”
All times listed are UTC, unless otherwise noted.
Amateur solar observer Tad Cook, K7RA, of Seattle, Washington, provides this weekly report on solar conditions and propagation. This report also is available via W1AW every Friday, and an abbreviated version appears each Thursday in The ARRL Letter. You can find a guide to articles and programs concerning propagation here. Check here and here for a detailed explanation of the numbers used in this bulletin. An archive of past propagation bulletins can be found here. You can find monthly propagation charts between four USA regions and 12 overseas locations here. Readers may contact the author via e-mail.