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ARRL Propagation Bulletin ARLP007 (2013)

ARLP007 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 7  ARLP007
From Tad Cook, K7RA
Seattle, WA  February 15, 2013
To all radio amateurs 

ARLP007 Propagation de K7RA

Low levels of solar activity continue, the same as the past few
weeks. Sunspot numbers remain remarkably consistent, with average
daily numbers for the four reporting weeks since January 17 at 56.4,
55.7, 50.7 and finally 51.3 for the past week. As you can see,
average daily sunspot numbers rose less than a point from the
previous week to the past week.  Average daily solar flux receded
2.4 points to 104. Geomagnetic conditions remain calm.

The ARRL International DX CW Contest is this weekend. Conditions
will probably be about the same as last year, because solar activity
is about the same as this time in 2012. See for contest details.

The latest prediction for solar flux shows values of 100 for
February 15-16, 105 on February 17-19, 100 on February 20-22, 115 on
February 23-24, 110 and 105 on February 25-26, 100 on February 27
through March 3, 95 on March 4-9,115 on March 10 and 120 on March

The predicted planetary A index is 5 on February 15-20, 9 on
February 21-22, 8 on February 23, 5 on February 24-28, then 10 and 8
on March 1-2, and 5 on March 3-17.

Every week F.K. Janda, OK1HH gives us his thoughts on geomagnetic
conditions over the next few weeks. Generally for HF propagation,
particularly for the higher bands (10-20 meters) we would like to
see very little geomagnetic activity, but with as many sunspots and
as much solar flux as possible. We have seen a lot of quiet
geomagnetic conditions over the past few years, but not much in the
way of sunspots or high solar flux values.

OK1HH suggests the geomagnetic field will be quiet to unsettled on
February 15-16, quiet on February 17-21, quiet to active February
22, active to disturbed February 23, mostly quiet February 24-25,
quiet February 26-28, quiet to unsettled March 1, quiet to active
March 2, mostly quiet March 3, quiet to unsettled March 4, quiet
March 5-6, mostly quiet March 7-8, quiet March 9, and quiet to
active on March 10.

Don't miss the article in the March issue of QST, by Carl
Luetzelschwab, K9LA titled "The Sun and the Ionosphere." It begins
on page 48, gives an update on Cycle 24, and discusses measuring the
Sun and ionosphere and relating solar flux to MUF, or Maximum Usable

Neil Shapiro, W2NLS of Bethpage, which is on New York's Long Island,
asked about relating the information in these bulletins to practical
on-the-air results.

I suggested checking out the resources listed at the bottom of each
bulletin, from the ARRL Technical Information Service and also the
resources from the K9LA website.

One useful tool is to download the free program W6ELprop (which
works on the Windows operating system) from

You will need to enter your latitude and longitude for your default
station location, and a useful tool for converting street addresses
to geographical coordinates is at

You can use an average of the previous 5 days sunspot numbers from

For the K index, either use the latest Middle Latitude numbers from

Or use the planetary number from WWV:

I ran the numbers for Neil on February 15, from his QTH to the Czech
Republic. It looks like 15 meters is a good bet from 1430-1700z, 17
meters 1330-1800z, and 20 meters over the same period as 17 meters,
but stronger signals on 17 meters (assuming power levels and
antennas are equal).  It looks like 30 meters should open up around
1800z, and have strongest signals 2130-0100z, and 40 meters
2000-1000z, with best signals around 2230-0630z.

An alternative to sunspot numbers would be to use solar flux.  You
can set W6ELprop to default to either type, or change it on the fly
by entering F103 (for example) as solar flux of 103, or S66 as
sunspot number of 66.

The engine used for driving W6ELprop was originally designed to work
with the predicted smoothed sunspot number for the month, and it
doesn't really work well to try to use the latest day's numbers.  So
an average for the past 5 days is a compromise.

Another useful tool is a new one from Stu Phillips, K6TU of
Woodside, California:

This one is interesting.  You subscribe to this service (but I think
there is a free trial) and tell it what kind of prediction you want
to run, then after making the calculations, it emails a link that
you use to display them.  For each band, you can step through
hour-by-hour to see maps showing where your signals will be
strongest, with different colors used to express different signal
levels. It is interesting to see how the coverage areas shift,

We heard from Peter Thulesen, OX3XR in Nuuk, Greenland. He wrote,
"Just to report my observations on 28 MHz propagation from Greenland
(grid GP44) to North America, US and VE in the evenings after sunset
here in Greenland. Around 2000-2200 UTC I very often have worked
several/many stations on 28 MHz CW from all US and VE. This has been
the situation January 2013. In the weekends where I have the
possibility to monitor the bands during the day 28 MHz seems to be
more dead towards W and VE than in the evening just after sunset.

"In the evening after sunset 28 MHz seems dead listening on the
band. However, after calling CQ a few times around 28.025 MHz W and
VE stations start to answer my call. The signal strength is good up
to 599 and stable signals with only little QSB.

"When conditions have dropped for CW contacts I can normally
continue working JT65 stations on 28 MHz, maybe another 30-45
minutes. I'm using a sloping dipole toward Europe and 100 watts."

Jeff, N8II of West Virginia wrote: "The seasonal changes we expect
on the bands are occurring. Long path propagation has disappeared on
30 meters into SE Asia and the evening openings much improved on 12
thru 20 meters into East Asia. We get JAs some nights in the 2200Z
hour on 12, 15 is better and on 20 CW the JTs, JT1AA/3 and JT1E, are
much louder around 0100Z along with good openings to UA0U area which
were almost nil in mid January.

"Conditions have been quite good at times into central Asia on the
low bands. 4S7NE was logged around 0125Z on 40 meters CW on the
February 8, T6LG continues to be active on 80 CW and EY8MM was also
heard around their sunrise.

"I had quite a struggle completing a QSO with K7EKD near Seattle for
his last state on 160 meters due to high noise on his end, but we
made it at 0200Z on the February 7."

When Jeff mentioned K7EKD, I thought the call sounded eerily
familiar. K7EKD taught electronics in my high school. I spoke with
him a few times, but unfortunately was expelled from school (hey, it
was the late 1960s!) before I got around to taking any of his
classes. At that point I was WA7CSK and had been on the air four
years. It was certainly an interesting time to be a teenager.

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 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 February 7 through 13 were 58, 57, 58, 45, 60,
55, and 26, with a mean of 51.3. 10.7 cm flux was 102.8, 104.2,
107.6, 105.9, 105.2, 101.8, and 100.3, with a mean of 104. Estimated
planetary A indices were 6, 7, 3, 4, 4, 4, and 11, with a mean of
5.6. Estimated mid-latitude A indices were 7, 8, 3, 3, 3, 3, and 9,
with a mean of 5.1.


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