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ARRL Propagation Bulletin ARLP028 (2006)

ARLP028 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 28  ARLP028
From Tad Cook, K7RA
Seattle, WA  July 14, 2006
To all radio amateurs 

ARLP028 Propagation de K7RA

Sunspot numbers and solar flux declined this week.  Average daily
sunspot numbers dropped 10 points to 25.6, and average solar flux
was down nearly 11 points.  There were no remarkable geomagnetic
disturbances.  July 9 saw a weak solar wind from a coronal mass
ejection, followed by another period two days later, but every day
the IMF pointed north, protecting Earth's geomagnetic field.

The latest forecast calls for solar flux around 70 over the next
week, lower than it has been lately.  Sunspot numbers should also be
low.  Predicted planetary A index for July 14 is 8, and then 5 for
the next week.

Eric Hall, K9GY of Lansing, Illinois reminds 6-meter operators (or
anyone with a 6-meter radio for that matter) to operate the CQ World
Wide VHF Contest this weekend.

Six meters continues to amaze.  July 12 saw great openings, with
European stations working North America.  A check of 6-meter DX
spots for the previous 36 hours on July 13 at
showed several thousand entries over a 24-hour period.  EH8BPX in
Canary Islands showed up 35 times in 36 hours, entries either from
or about him.  He seemed to work many stations on the East Coast and
in the Midwest.

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 July 6 through 12 were 34, 35, 34, 33, 18, 13
and 12 with a mean of 25.6. 10.7 cm flux was 85, 79.9, 77.4, 74.6,
72.8, 71.2, and 70.6, with a mean of 75.9. Estimated planetary A
indices were 11, 6, 3, 5, 11, 7 and 12 with a mean of 7.9. Estimated
mid-latitude A indices were 7, 5, 2, 5, 12, 5 and 9, with a mean of


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