ARRL Propagation Bulletin ARLP035 (2009)

ARLP035 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 35  ARLP035
From Tad Cook, K7RA
Seattle, WA  August 28, 2009
To all radio amateurs 

ARLP035 Propagation de K7RA

Last week's Propagation Forecast Bulletin ARLP034 reported that the
sporadic-E season was probably over, but then we heard from Mark
Bell, K3MSB of Airville, Pennsylvania (FM19ut).  He reports that
nine days ago on August 19 he worked KG4NL in Guantanamo Bay (FK29)
on 6 meter CW at 2208z.

KG4NL was weak in Pennsylvania with significant QSB, where Mark was
running 100 watts into a five element Yagi at 20 feet.

Bill Rinker, NE9Z in Moran, Wyoming wrote in to ask how the Solar
Flux Index is measured.  Bill is in the Teton National Forest, about
20 miles south of Yellowstone National Park.

The solar flux readings are done at an observatory in Penticton,
British Columbia, three times per day.  The one we use for the
official solar flux is the noon reading.  The other readings are
done in the morning and afternoon.

You can see all of those readings for the past few years at  The ones to pay attention to are the
readings at 2000z (which are shown in the table as 200000 in the
second column) and the observed flux values are in the fifth column.
The sixth column shows adjusted flux values, which are corrected for
variations in the distance from Earth to Sun.  The adjusted values
may be useful for measuring what the Sun is doing, but the observed
flux gives an indicator of the relative amount of 2.8 GHz energy
that is reaching Earth.  10.7 cm is the approximate wavelength at
2.8 GHz.

The page at has more detailed
information about the solar flux under "Information about the

Mark Lunday, WD4ELG of Hillsborough, North Carolina notes that as
the Summer season slowly wanes, static on the lower frequencies is
subsiding.  Mark recently worked VQ9LA on 80 meters CW with 100
watts and a modest vertical.

Jeff Lackey, K8CQ of St. Simons Island, Georgia has written to us
before with his observations on the number of zero sunspot days
between cycles.  This time he sent a graphic showing how this
minimum is similar to the one prior to Cycle 19 (the big one) and
earlier cycles, rather than more recent cycles after 19.

Currently we have had 48 continuous days of zero sunspots.  Jeff
said if this continues for the next couple of days, it will be the
only cycle minimum since 1855 with two greater than 50 day runs of
zero spots.  Back then it was the transition to Cycle 10.  It is
happening right now, and it happened in 2008 also.

He notes, "There is still DX to be worked.  You just have to be very
patient.  I heard the V73NF station on 40m CW earlier this week (Aug
24) about 1100 UTC but they didn't seem to be coming back to anyone
in NA.  So I'm not sure they were hearing very well.  They finally
went QRT and left a lot of us exasperated.  This morning the
KH2/K7BV operation was quite strong but the QRM for me was too much
to be heard.  They worked several NA stations from 1230 to 1300 UTC
but I never could crack the pile up.  I've got both DXCC entities
before in previous operations; so I wasn't totally bummed out."

Jeff works all his DX with a flagpole antenna and by loading up his
rain gutter.

Geophysical Institute Prague predicts quiet to unsettled conditions
August 28, quiet August 29-30, quiet to unsettled August 31,
September 1 quiet, quiet to unsettled September 2, and active
conditions on September 3.

NOAA and the U.S. Air Force predict planetary A index for August 28
through September 6 at 5, 7, 10, 7, 5, 12, 7, 5, 8 and 6.

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

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

Instructions for starting or ending email distribution of this
bulletin are at

Sunspot numbers for August 20 through 26 were 0, 0, 0, 0, 0, 0, and
0 with a mean of 0.  10.7 cm flux was 67.6, 66.4, 66.6, 67.3, 67.6,
67.1, and 67.3 with a mean of 67.1.  Estimated planetary A indices
were 11, 8, 5, 5, 3, 3 and 4 with a mean of 5.6.  Estimated
mid-latitude A indices were 8, 6, 3, 3, 1, 2 and 4 with a mean of