ARRL Propagation Bulletin ARLP043 (2006)

ARLP043 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 43  ARLP043
From Tad Cook, K7RA
Seattle, WA  October 20, 2006
To all radio amateurs 

ARLP043 Propagation de K7RA

Sunspot numbers this week were 0 on every day. In fact, 0 was the
sunspot number for eight days in a row, from October 11 through 18.
On October 19 a single sunspot appeared, sunspot 917, in the center
of the solar disc as seen from Earth, and this resulted in a sunspot
number of 14. Due to the way sunspot numbers are calculated, there
are no sunspot numbers from 1 through 10, only 0 for the minimum and
then 11 for the next number. Judging from numbers ten years ago at
the last solar minimum, we should observe longer periods of no
sunspots, several weeks in a row, or perhaps over a month.

In late 1995 we began to see short stretches of time with no spots.
Then there were 12 days in a row, February 3-14, 1996 that were
spotless. We began to observe one to two week stretches with 0
spots, except for one or two days in the middle. May 18-21, 1996 had
no spots, then the next two days recorded 11 and 12, then May 24-31
had no spots. In fall 1996 we saw a really long stretch, September 9
through October 24 1996, with only two days in that period with
recorded sunspots. September 13 through October 20 had no spots at

After this, the spotless days were less and less common, with some
strings of 7-10 spotless days in early 1997. By the fall of 1997,
things were jumping again. October 1996 had an average daily sunspot
number of only 2.3, October 1997 was 33.5, October 1998 was 77,
October 1999 was 167.7, October 2000 was 138.9, and the average
daily sunspot number in October 2001 was 197.4. So far October 2006
has an average daily sunspot number of 13.1, so we have a bit to go
before we see the typical bottom-of-the-cycle month of no sunspots.
The predicted sunspot minimum is still about 6 months away.

Just because there are no sunspots, does that mean HF radio is dead?
No, in fact it is better for 160 and 80 meters. But even higher
frequencies will have openings to somewhere, although not as
frequently as during periods of higher sunspot activity.

John Plenderleith, 9M6XRO of Eastern Malaysia wrote to say that last
Friday October 13, the third day in a row with 0 sunspots, he worked
OM3EY in the Slovak Republic on 12 meter CW, and they moved the QSO
to 10 meters. Conditions weren't very good, but signals were
copyable, and then, in John's own words, "Suddenly - bam - the band
was wide open and in the next 2-1/2 hours I worked 283 stations from
all over Europe, a few in the Middle East, J28JA and a solitary JA.
For much of the time I had 18db attenuation in on my FT-1000MP and
signals were still S9 on the meter - a solid wall of stations! The
opening ended at 8:35 PM local time - whereas local sunset was at
6pm. It brought back memories of 1957/58 when I was an SWL and 10
meters was wide open every day!"

8:30 PM local time was 1235z. Local sunset was around 1000z. John
continues, "Just goes to show, even at this point in the cycle, it
pays to go on the bands and fill up those empty frequencies - you
never know what might happen!"

Rick Fleeter, K8VK of Reston, Virginia has been a ham since he was 9
years old, in 1963. He likes the quiet conditions that come with
lower sunspot activity. He writes, "I've been a ham since the mid
'60s so have survived several cycles now. I find low sunspot cycles
the best times for radio work in HF. I'm not just talking about the
top bands. There is not much difference between sunspot activity and
simple every daytime solar excitation of the ionosphere. Except that
at near 0 sunspots, the progression of propagation during the day is
completely rhythmic with the daily clock, and predictable."

Rick continues, "The longer wavelength bands are much quieter at
night when the sun is quiet, and even with no sunspots, 20, 15, even
10 meter openings are quite regular during the day. Plus it seems
like a less opaque ionosphere eliminates QRM from nearer stations
(QRN as well does not propagate so well from nearby sources, which
is most of it), so the DX which is there, is easier to hear."

This weekend we could have more days with 0 sunspots, or at a
maximum, sunspot numbers from 11-15. A solar wind stream is expected
to cause active geomagnetic conditions today, October 20, with the
October 20-23 planetary A index predicted at 20, 13, 8 and 5.
Geophysical Institute Prague predicts declining geomagnetic
activity, with active conditions on October 20, unsettled to active
on October 21, unsettled October 22, quiet to unsettled October 23,
unsettled October 24, and quiet conditions on October 25-26.

Eric Hall, K9GY of Lansing, Illinois wrote to ask readers to
participate in the Illinois QSO party and the Worked All Germany
contest this weekend. Details are at for the German activity
and for Illinois.

In a week many hams will begin the CQ World Wide DX Phone contest
weekend. Current predictions show planetary A index for October
27-29 of 12, 25 and 8. The Saturday number of 25 looks a little

If you work the German contest this weekend, what are some good
times to check the different bands? It depends on your location, but
from Boston, 80 meters looks promising from 2030-0800z, with best
bets around 0000-0530z, 40 meters 1900-0200z and 0430-0930z. 20
meters looks good 1200-1900z, and 15 meters could possibly be open
1230-1800z, with the best bet around 1500-1630z. All of this assumes
a sunspot number of 11, which may be a bit optimistic.

From Atlanta to Germany, 80 meters looks good 2130-0730z, with best
signals around 0000-0600z. Try 40 meters 2130-0330z, or 0600-0930z,
with best signals around 2200-0200z. 20 meters looks good
1330-1830z. Slim chance of any 15 meter opening, but best chance is
around 1430-1700z.

From the center of the continental United States, Germany looks best
on 80 meters 0030-0700z, and 40 meters 2230-0330z and 0700-0930z.
20 meters is most promising 1430-1900z and 15 meters possibly, but
not likely, 1600-1730z.

From North Texas, 80 meters 0100-0630z, 40 meters 2300-0930z, 20
meters 1330-1730z, with signals declining over that period, and
possibly again around 1930z. Unlikely but possible is 15 meters

From Chicago, 80 meters 2330-0700z, 40 meters 2130-0230z and
0700-0800z. Check 20 meters 1500-1800z.

Salt Lake City, 80 meters 0100-0700z, 40 meters 0700-1000z and
2300-0500z. Check 20 meters 1530-1900z.

From Los Angeles, 80 meters 0100-0800z, best around 0330-0500z. 40
meters 0030-0800z and 20 meters 1500-1630z.

From Seattle, 0000-0730z on 80 meters, and on 40 meters, 2200-1030z,
1200-1300z and 1430-1630z. Check 20 meters 1630-1800z.

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 a detailed
explanation of the numbers used in this bulletin, see An archive of past
propagation bulletins is at .

Sunspot numbers for October 12 through 18 were 0, 0, 0, 0, 0, 0 and
0 with a mean of 0. 10.7 cm flux was 73.6, 73.3, 72.4, 71.1, 69.5,
69.6, and 69.5, with a mean of 71.3. Estimated planetary A indices
were 5, 24, 18, 10, 8, 2 and 4 with a mean of 10.1. Estimated
mid-latitude A indices were 3, 15, 12, 9, 7, 2 and 2, with a mean of