ARRL Propagation Bulletin ARLP038 (2010)

ARLP038 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 38  ARLP038
From Tad Cook, K7RA
Seattle, WA  September 24, 2010
To all radio amateurs 

ARLP038 Propagation de K7RA

The autumnal equinox occurred early yesterday, at 0309 UTC on
September 23.
Conditions were good this week, with sunspots visible every day, and
very little geomagnetic activity.  Average daily sunspot numbers
rose more than 24 points to 40, and average daily solar flux was up
nearly five points to 82.9.  Solar flux was expected to rise to 88
for September 23-27, but instead it was 84.3 on September 23, and
now the forecast for September 24-28 is solar flux three points
lower, 85.  For September 29-October 5 the solar flux forecast is
84, 82, 82, 82, 80, 78 and 76.
Planetary A index for September 24-30 is predicted to be 10, 7, 5,
5, 7, 8 and 5.  Geophysical Institute Prague predicts quiet to
unsettled conditions on September 24, quiet conditions September
25-27, quiet to unsettled September 28, and quiet again on September
Bill Magruder, KD7KST sent in an interesting link showing live
aurora from Yellowknife in Canada's Northwest Territories, which is
at 62.433 degrees north latitude.  Go to
and have a look, after dark, of course.  This weekend sun sets in
Yellowknife around 0125z and sunrise is at 1334z.
Alfio Bonanno, IT9EJW in Italy operates a 10-meter beacon on 28.226
MHz.  He reports that for the first time since the beacon was put on
the air in 2008, it was heard outside Europe.  LW3EX in Buenos
Aires, Argentina copied it at 1647z on September 15.  Information on
the beacon is at
WorldRadio online has a new monthly propagation column from Carl
Luetzelschwab, K9LA, this time with his observations about the rise
time for solar cycles compared to the current cycle 24.  You can
find it at
Dave Ripton, K6SIX of Morris Plains, New Jersey commented about a
recent question concerning TVI on six meters.  Dave wrote, "In this
week's bulletin you mentioned the improvement in 6M TVI.  We have to
thank the cable, satellite, and fiber optics companies for the
reduction in 6M TVI.  In my Northern NJ area, roof top TV antennas
are rare and the ones that are there are rusted-out so I expect they
are no longer used.  With Channel 2 gone even indoor 'rabbit ears'
are no longer a problem.  Also telephone RFI has dropped thanks to
the new wireless phone bands.  With all the new rigs that included
6M it is a great band for newcomers as well as 6M nuts like myself.
Now all we need is some F2 to really bring 6M's back to life".
John Ragle, W1ZI of Hadley, Massachusetts wrote "I run 350 watts
(peak) output on 50 MHz to a 5 element beam about 30 feet up and
about 50 or 60 feet from our house and a neighbor's house.  The TV
and Internet cable come in on underground fiber optic, and cross the
street underground as double-shielded coax.  The run from the sill
junction box on the house to the interior of the house is with
ordinary single-shield coax.  I also run about 350 watts (peak) on 2
meters and 90 watts on 70 cm, as well as 100 watts on HF.  There is
not the slightest hint of TVI in either location...although my
wife's sound system (her computer sound card is hooked to an FM
radio's audio in) picks up some crackle from the modulation peaks in
the 2 meter band".
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 an explanation of
the numbers used in this bulletin, see  An archive of
past propagation bulletins is at  Find more good
information and tutorials on propagation 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 16 through 22 were 46, 41, 42, 50, 38,
37, and 26 with a mean of 40.  10.7 cm flux was 82.5, 82.2, 82.1,
81.2, 82.6, 84.6 and 84.8 with a mean of 82.9.  Estimated planetary
A indices were 6, 8, 4, 4, 4, 6 and 2 with a mean of 3.7.  Estimated
mid-latitude A indices were 5, 7, 2, 2, 3, 5 and 1 with a mean of