ARRL

ARRL Propagation Bulletin ARLP029 (2007)

SB PROP @ ARL $ARLP029
ARLP029 Propagation de K7RA

ZCZC AP29
QST de W1AW  
Propagation Forecast Bulletin 29  ARLP029
From Tad Cook, K7RA
Seattle, WA  July 13, 2007
To all radio amateurs 

SB PROP ARL ARLP029
ARLP029 Propagation de K7RA

The average of daily sunspot numbers for this reporting week, July
5-11, were about the same as the previous seven days, declining
slightly by less than two points.  We've seen no zero sunspot days
since an eleven-day spotless period ended on June 25.  If sunspot
numbers continue at this level and higher, it will become easier to
convince ourselves that the sunspot minimum is already behind us
(see the table of 3-month moving averages in last week's bulletin
ARLP028 at http://www.arrl.org/w1aw/prop/2007-arlp028.html).

On July 11 the Air Force had a prediction for heightened solar flux
(probably indicating more sunspots) from July 13-15 (see
http://tinyurl.com/yonktp).  Alas, by Thursday afternoon the
predicted solar flux had dropped ten points (see
http://tinyurl.com/2ffq9n) from 85 to 75 for the same period.  Using
some very rough approximations plus maybe a fudge-factor or two,
this might be reflected in a slightly greater than thirteen point
difference in the expected daily sunspot number.

Predicted planetary A index for July 13-19 is 8, 10, 8, 8, 8, 15 and
20. For the same period Geophysical Institute Prague predicts quiet
to unsettled conditions for July 13, unsettled July 14, quiet July
15-17, and unsettled July 18-19.

Wade Grimes, K0MHP of Elsberry, Missouri wrote to ask if six meters
is the ''magic band, or invisible band?''  He isn't hearing the
propagation on six reported in this bulletin.  He's having much
better luck on 20 meters, although he is constructing a quad antenna
for six, and he does copy some distant beacon signals.

I should point out that not everyone is hearing DX on six, but still
the reports come in from those who are patient and lucky.  Ken Tata,
K1KT sent in more examples via maps generated at vhfdx.net .  Poke
around this site, and you will find both current real-time maps
showing propagation on 2 and 6 meters for both North America and
Europe, and some fine examples of recent propagation on some
archived maps.

Howard Runyons, W4HLR of Newbern, Tennessee (EM56jb) wrote about he
and N4QWZ (EM66) both working W7CI (DM41) in Sierra Vista, Arizona
on 2 meters on June 27 at 2349z.  Howard ran 50 watts through
hard-line to a 15 element beam at 40 feet.

Mark Roberts, KD5SMF of Fairview, Oklahoma has been enjoying both 6
and 10 meters, and he recently took a trip up Gloss Mountain
(EM06xj) to see what he could work on both bands.  At over 1500 feet
on July 7, he worked 41 stations on 10 meters, nearly all to the
southeast and northeast.  He worked one station in Anaheim,
California.  As the propagation moved, he got many reports of 10 db
over S9, but after moving west, propagation shut down.  You can see
a photo of him and his portable operation at
http://www.qrz.com/kd5smf.

Thanks to David Sumner, K1ZZ of Coventry, Connecticut, who pointed
out that in last week's bulletin the call sign for John Butrovich is
W5UWB, not W6UWB.

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service at
http://www.arrl.org/tis/info/propagation.html. For a detailed
explanation of the numbers used in this bulletin, see
http://www.arrl.org/tis/info/k9la-prop.html. An archive of past
propagation bulletins is at http://www.arrl.org/w1aw/prop/ . Monthly
propagation charts between four USA regions and twelve overseas
locations are at http://www.arrl.org/qst/propcharts/.

Sunspot numbers for June 5 through 11 were 24, 12, 23, 16, 20, 25
and 28 with a mean of 21.1. 10.7 cm flux was 71.5, 71.1, 73.1, 75.1,
77.1, 78.1, and 78.5, with a mean of 74.9. Estimated planetary A
indices were 5, 5, 6, 4, 3, 6 and 23 with a mean of 7.4. Estimated
mid-latitude A indices were 3, 4, 4, 3, 2, 5 and 14, with a mean of
5.
NNNN
/EX