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The K7RA Solar Update


Conditions were good for Field Day weekend, with no major geomagnetic disruptions, while solar flux and sunspot numbers were relatively high for this part of the solar cycle. On Friday, Saturday and Sunday the sunspot numbers were 41, 34 and 16 while solar flux was 80.3, 77.1 and 74.5.

Planetary A index was 4, 16 and 7 on Friday through Sunday. On Saturday the College A index in Alaska reached 24, so I imagine Field Day stations in Alaska and Canada’s northern latitudes suffered a bit, although I’ve received no reports. College K index was 4 at 0600 UTC, then 2 at 0900 UTC, then 5, 5 and 4 on 1200-1800 UTC.

But the middle-latitude A index (measured in Virginia) was 15 on Saturday, and the K index reached four on only two periods, at 1200 UTC and again at the end of the UTC day 12 hours later. Otherwise the mid-latitude K index varied from 2-3.

No sunspots are visible since Tuesday, June 26. Average daily sunspot number was 22.6 this reporting week (June 21-27), down slightly from the previous week’s average of 25.7.

Average daily solar flux increased this reporting week from 74 to 75.3.

Average planetary A index increased from 6.7 to 9.9.

Predicted solar flux is 70 on June 29, 68 on June 30 through July 6, 72 on July 7-13, 75 on July 14-15, 77 on July 16, 80 on July 17-19, 77 on July 20-21, 75 on July 22, 72 on July 23-24, 70 on July 25-26, 68 on July 27 through August 2, 72 on August 3-9, 75 on August 10-11 and 77 on July 12. 

Predicted planetary A index is 8 on June 29 to July 2, 5 on June 3-14, 15 on July 15, 5 on July 16-19, 15 on July 20, 8 on July 21-22, then 10, 25, 18, 12 and 8 on July 23-27, 5 on July 28 through August 10, 15 on August 11 and 5 on August 12.


Jon Jones, N0JK, reported a 6-meter opening to Asia on Thursday, June 21: “There was a major sporadic-E opening on 50 MHz between Japan, China, Korea and North America. Hundreds of contacts were made, most via FT8. 

“I got off work at 2130 UTC and drove home to Lawrence from Kansas City. I had seen some spots that a good opening to Japan was developing prior to leaving work. I stopped at the I-70 Lawrence rest stop at 2200 check the band. 

“Monitoring FT8 signals at 50.313 MHz with just a 1/4 wavelength mag-mount whip antenna, I decoded JA8XTG, JH8XVH, JP1LRT, JH7DFZ, JE1BMJ, JG3IFX/8, CM2XN, JA1UAV, JE1BMJ, and JA7QVI. 

“I tried to work some of the JAs, but the mobile setup was unable to get through. I went home, got my portable set up with a 2-element Yagi antenna and tried again at 2315 UTC. I was able to work several JAs, including JA7QVI and JA9SJI. I managed to get one decode of BH4IGO. The opening got weaker after 2340, but Japanese stations were still working Cuba, Cayman Island and other islands in the Caribbean. Larry, N0LL, said signals were strong enough he worked a few JAs on CW.” 


On June 28 Mark Lunday, WD4ELG, of Greensboro, North Carolina reported: “Fifteen meters has been almost completely dominated by trans-equatorial propagation for many days, primarily using FT8. Suddenly, at 2200 UTC today, I start picking up 9K2HS (Kuwait) calling CQ! Then I hear SP2HQP (Gdansk, Poland). 

“I have been working Europe on 17 and 20 meters, but this is the first time in a while that 15 has been open in the Europe-to-Southwest Asia path in a while." 

(Trans-equatorial propagation involves signals that seem to be propagating only over a north-south path, across the equator).


Last week, on June 22, Bob German, KG6PJG, of Big Bear Lake, California reported: “I maintain an APRS VHF I-gate from my home, located at an elevation of approximately 7,260 feet. Most packets received are from a localized area with a few from more distant locations. However, on June 19 from 1646 to 1837 UTC, I received some very surprising packets. I believe this was likely due to unusual atmospheric conditions that were reflecting 2-meter, and likely 6-meter, signals much further than normal. These packets were sent from Arkansas, Kansas, and Oklahoma with the most distant being 2,168.3 km. The sending locations can be viewed at: 

My station consists of a Kenwood TMV71A using a Diamond X300A antenna. The APRS software is Direwolf and APRSIS32. 

“I would guess that other amateur services probably experienced these conditions and I thought it might of some value to pass along. I have no experience with VHF DXing but hope to engage in this activity in the future.”

Looks like Bob observed some nice VHF sporadic-E propagation.


Jeff, N8II, of Shepherdstown, West Virginia reported last Sunday, June 24: "It would seem that magical things would happen with such a drastic increase in the Solar Flux Index with low K index, but at times, especially around 1200-1300Z on 20 meters things have seemed pretty unchanged from when the SFI was in high 60s. I did work some European and Asiatic Russians, as well as Finland, Israel, and UN6P in Kazakhstan at around 0200 to 0300 UTC on 20-meter CW on June 22. The next night was not nearly as good. There was almost no sporadic E on any band during Field Day Saturday, followed by tremendous Es on Sunday! 

“I did notice some improvement on 17 meters around 1300Z (signals were still quite weak, however) and some late openings to Europe on 17 meters. Japanese stations have been loud, but very few, on 20 meters 1200Z and probably earlier." 

In the Correspondence section of the July 2018 issue of QST, Bob Kozlarek, WA2SQQ, of Elmwood Park, New Jersey points out that “…85-percent of my best 160-meter activity took place during the low part of the last solar cycle. While 10, 15 and 20 meters were quiet, I was very active on 160, 75 and 40 meters. It’s time to retune and start thinking about making the best of these situations. Days without sunspots can be a great time to explore new or seldom used bands or modes, such as 2-meter SSB and digital mobile radio.”

For more information concerning radio propagation, see the ARRL Technical Information Service at For an explanation of numbers used in this bulletin, see 

An archive of past propagation bulletins is at More good information and tutorials on propagation are at 

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

Instructions for starting or ending email distribution of ARRL bulletins are at 

Sunspot numbers for June 21 to 27, 2018 were 41, 41, 34, 16, 14, 12, and 0, with a mean of 22.6. 10.7 cm flux was 81.5, 80.3, 77.1, 74.5, 72.8, 71.1, and 70, with a mean of 75.3. Estimated planetary A indices were 3, 4, 16, 7, 12, 20, and 7, with a mean of 9.9. Estimated mid-latitude A indices were 4, 4, 15, 8, 10, 17, and 7, with a mean of 9.3.





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