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The K7RA Solar Update


The Autumnal Equinox is next Thursday, September 22, 2016 at 1421 UTC. This indicates a transition from summer to fall, and the associated improved HF propagation.

Over our reporting week (September 8-14) average daily sunspot numbers rose from 46.4 to 50.1, and average daily solar flux declined from 95.1 to 88.9.

This is the opposite of what occurred the previous week, when sunspot numbers declined and solar flux rose. Normally we expect solar flux and sunspot numbers to track together.

Geomagnetic indicators were very quiet, with average daily planetary A index declining from 26.6 to 6.7, and mid-latitude A index from 18.1 to 6.1.

The latest NOAA/USAF forecast has solar flux at 85 on September 16-17, 80 on September 18-19, 75 on September 20, 80 on September 21-22, 75 on September 23-24, then 72, 78 and 80 on September 25-27, 78 on September 28-30, 82 on October 1-2, 80 on October 3-7, then 82, 86 and 82 on October 8-10, 80 on October 11-12, 75 on October 13-14, 70 on October 15-16, and 75 on October 17-21, then 72, 78 and 80 on October 22-24.

Predicted planetary A index is 8 on September 16-17, then 5, 18, 20, 12 and 8 on September 18-22, 5 on September 23-25, then 15, 8, 38, 40 and 42 on September 26-30, then 30, 18, 15, 12 and 10 on October 1-5, then 5 on October 6-8, 15 on October 9, 8 on October 10-11, 5 on October 12-13, 12 on October 14-16, then 15 and 10 on October 17-18 and 5 on October 18-22.


“Geomagnetic activity forecast from OK1HH for the period September 16 to October 12, 2016

Geomagnetic field will be:

Quiet on September 18, 23-24, October 4-7, 11-12

Mostly quiet on September 16-17, 22, 25, October 3, 8

Quiet to unsettled on September 21, 26-27, October 2, 9-10

Quiet to active on September 19-20, October 1

Active to disturbed on September 28-30

Increases in solar wind from coronal holes are expected on September (18,) 22, 26-28, October 1.


- Parenthesis means lower probability of activity enhancement.

F.K. Janda, OK1HH

Czech Propagation Interest Group”


A note here from K7RA about minor changes to this weekly Czech geomagnetic bulletin, which I edit in an effort to put the translation in more standard English. Where it reads “increases in solar wind” the actual original text is “amplifications of solar wind.” Also where it reads, “Czech Propagation Interest Group”, the original text reads, “Czech Propagation Interested Group.”


Jeff Hartley, N8II, in Shepherdstown, West Virginia wrote on September 9:

“I have not been very active this week, but can report generally poor conditions except fairly good paths to mid and southern Europe on 20 meters, excluding Russia. The nearly constant disturbances had their effect during the weekdays and over the weekend when I took part in the Colorado and Tennessee QSO parties. Twenty meters was poor to Colorado until about 1900Z Saturday, but there were some booming signals on 20 in the evening and I made two QSOs with W0ETT/M (mobile) on 40 over an all-daylight path. Sunday was good to Tennessee on 40 meters and below, but 20 meters was very poor with only weak backscatter. 

“I worked TY2AC in Benin, Africa on 15 meters CW around 2030Z Thursday when he was S 2-3; today he was S9 around 1530Z and some southern Europeans were also coming through when the K index finally reached 1. All week the K index seems to have varied between 3 and 5 with rare 2s.”


Ken Roth, KX6X, in Sierra Vista, Arizona wrote:

“There have been a number of guys and gals warning that even when a band appears to be ‘dead’, that it may not be dead; it's just that no one is transmitting. That was proved last evening (September 9) when I turned on my rig around 0415 UTC and tuned through 20 meters. There was not a single signal to be heard. No SSB, no digital, no CW. Nothing. Zero. Nada.

“I then called CQ at 14.055 MHz with no responses. Then, at 0420 UTC, I tuned down to 14.020 MHz and heard JA7NUT calling "CQ" with a solid 569.

“I called him and he gave me a 579. And guess what? When I told him that he was the only signal on the band, he said that this was exactly the case for him in Japan as well.

“Think about it. In both Japan and the US, neither of us could hear any signals, and yet we ended up discovering that the propagation path between us was in very good shape! Proof once again, that the bands are not dead, it's just that we're not transmitting!”


This reminds me of something I read 50 years ago (many times in ARRL publications), when I was a young teenaged ham. There was an emphasis on instructing new hams to listen, above all else. Maybe this was an effort to encourage new radio operators to listen first before transmitting, but my impression at the time was that they were encouraging us to listen much more often than calling CQ. But if everyone is listening instead of calling, how likely would it be that they will discover paths over radio?


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 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 September 8 through 14 were 49, 65, 66, 63, 57, 27, and 24, with a mean of 50.1. 10.7 cm flux was 94.5, 91, 93, 86.4, 86.5, 86, and 85.2, with a mean of 88.9. Estimated planetary A indices were 14, 5, 5, 4, 6, 5, and 8, with a mean of 6.7. Estimated mid-latitude A indices were 12, 6, 4, 3, 6, 4, and 8, with a mean of 6.1.