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ARRL Propagation Bulletin ARLP007 (2007)

ARLP007 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 7  ARLP007
From Tad Cook, K7RA
Seattle, WA  February 15, 2007
To all radio amateurs 

ARLP007 Propagation de K7RA

This bulletin is out a day early. Look for the next bulletin on
Friday, February 23.

The sunspot number is currently 0, and the sun appears spotless, at
least from this side. A week ago, helioseismic holography detected a
spot on the far side of the sun, but whether it will fade away
before reaching our side is unknown. Currently a solar wind is
causing geomagnetic instability here on Earth, and the mid-latitude
K index is 5 at 0600z on February 15.

This week brought a couple of messages about propagation software.
Both noted that this bulletin frequently mentions W6ELprop. This is
because it is easy to use and free, as well as being easily
available. Each mentioned their favorite propagation software, and
wondered why it hasn't been mentioned here.

Steve Hammer, K6SGH of Santa Barbara, California suggested VOAProp
from Julian Moss, G4ILO. This is Windows freeware and serves as a
front end or shell for the free VOACAP software. To run VOAProp, you
download the setup file from, As
you install VOAProp, it directs the user to the VOACAP download
site. When executing the VOACAP setup file, it is best to let it
install in its default installation directory right at the root of
the hard drive (C:\).

The web site has instructions for using VOAProp, and the first thing
you'll want to do is set it up with your own latitude and longitude.
Then you click on the Solar Data button, and let it download the
predicted smoothed sunspot number for the month, in addition to
current data from WWV. Then you can set up the month and year, and
if you want, you can easily reset it for sunspot numbers higher or
lower than the current one, to try out different scenarios.

The program has a nice map display, and above it are buttons for
each of the 9 HF amateur bands, plus 160 meters. Yes, it does
include 160 meters, as well as 60 meters and the so-called WARC
bands at 12, 17 and 30 meters. Click a band-button, and it displays
a contour map showing what signals should be like in all directions
from your location. These are similar to contour maps showing
elevation for terrain, or weather maps that display contoured areas
for temperature or barometric pressure.

You can also see a 24-hour graph of probable signal levels between
you and any particular location. Just click on the map to draw a
line from you to any spot. You then click on Show Chart to bring up
the graph.

K6SGH has his own useful resources on the web. Go to, and look for a link to the Moxon Antenna
Project, where you can find plans for simple but effective homebrew
gain antennas based on designs by the late Les Moxon, G6XN.

Thomas Otterbein, DG8FBV was the other person who wrote, and he
suggested WinCap Wizard from Jim Tabor, KU5S, which is also based on
VOACAP. We'll try to get to that soon, but in the meantime check out
the KU5S software at,

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

Sunspot numbers for February 8 through 14 were 22, 11, 11, 0, 0, 0
and 0 with a mean of 6.3. 10.7 cm flux was 78.4, 76.7, 75.9, 74.7,
73.6, 72.7, and 72.7, with a mean of 75. Estimated planetary A
indices were 7, 4, 3, 2, 7, 17 and 18 with a mean of 8.3. Estimated
mid-latitude A indices were 6, 3, 2, 1, 4, 13 and 16, with a mean of


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