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ARRL Propagation Bulletin ARLP045 (2008)

ARLP045 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 45  ARLP045
From Tad Cook, K7RA
Seattle, WA  October 31, 2008
To all radio amateurs 

ARLP045 Propagation de K7RA

K7RA is on the road for a few days, and this bulletin comes to you
via a very weak Wi-Fi signal in Atlanta, Georgia.

Cycle 24 slowly builds momentum.  We saw sunspots for eight days in
a row, from October 10-17, then twelve days of no spots.  Now on
October 30 another sunspot appeared, numbered 1007 and from cycle
24.  It is a high latitude sunspot, and may provide some fun for
this weekend's ARRL CW Sweepstakes.  After a calendar year of very
few sunspots, this is the fourth time during October that sunspots
have emerged, and all from the new solar cycle 24.

Of course Sweepstakes is a domestic North American contest, but it
would be nice to have some propagation on 15 and 10 meters.

For a comparison, we look at W6ELprop (
to compare zero sunspots over this weekend to several days of two
sunspot groups (a sunspot number of 24, for example).  We will look
at two paths, the first from Beaverton, Oregon to Savannah, Georgia,
and the second, from Cleveland, Ohio to Central California.  Because
this is a contest weekend, we will only consider the five bands used
in most contests, 80, 40, 20, 15 and 10 meters.

From Oregon to Georgia, with zero sunspots we see little or no
likely 10 or 15 meter propagation.  20 meters looks good from

40 meter propagation is best from 2230-0130z, fair from 0900-1100z,
signals may disappear around 1330-1430z, and there is propagation
building throughout the day from 1500-0130z, with the weakest
daylight signals around 1730-1900z.

80 meters looks strong 0200-1130z, from after sunset in Oregon until
prior to sunrise in Georgia.

With a sunspot number of 24 for several days, 15 meters has a
possible opening 1830-1930z, 20 meters 1600-2200z, and 40 meters
looks good 2200-0430z, then with excellent signals 0800-1300z, and
weakest 1630-2000z.  80 meter propagation should be about the same
as with no sunspots.

From Ohio to California, with zero sunspots 15 meters might open
1600-2130z, with a better chance 1730-1930z.  20 meters should be
good 1430-1500z, then 1700-2000z, and 2200-2330z. 40 meters should
be open nearly around the clock, with weak signals around 1300z,
strongest signals 0100-1230z, and strong again at 1400z and again at
2300z.  80 meters should open after 2200z, with strongest signals
0300-1200z, and weak or no signals during daylight from 1500-2200z.

With a sunspot number of 24 sustained for several days, from Ohio to
California 15 meters comes alive with excellent signals for most of
the day, 1630-2130z.  20 meters opens 1400-0030z with weak spots at
1530z and 2100z.  40 meters should be open 24 hours a day, with
strongest signals 0100-1230z, then again around 1400z and 2300z,
weakest 1700-2000z.  80 meters looks about the same, but opening
slightly later than with zero sunspots.

Propagation programs give us some general guides to openings, based
on statistical models using smoothed sunspot numbers.

G3REP, Bob Parkes of West Sussex UK, sends along an interesting link
about visualizing the ionosphere, a subject not mentioned in this
bulletin for some time.  This bulletin first covered the subject
earlier this year on May 2 in ARLP019, which you can find in the
archive at

Bob is now semi-retired, but his telecom engineering work over the
past few decades has taken him all over the world.  In 1979-1981 he
was VS5RP in Brunei, P29PR in Papua New Guinea in 1983-1987, A45XF
in Oman from 1992 to 1993, and 4S7RPG in Sri Lanka, 1993-1997.  You
can read his bio and find a link to his photo at

Joaquin Montoya, EA2CCG wrote this week about conditions last
Friday, October 24.  He turned on his mobile rig to check conditions
before the CQ World Wide DX contest, and found everything dead in
the dead of night.  Conditions were also poor through the weekend
from his location in Spain.  But on October 29, perhaps around the
time our new sunspot 1004 appeared, he worked WH2P (Guam) on 15
meters.  He didn't say what time that was, but I might wager that it
was during his morning hours from 0700-1100z, perhaps around 0900z.

Joaquin has a very interesting blog at
which I found along with his photo at by
clicking on ''Detailed info''.

Many of us in the U.S. (myself included) unfortunately only speak
one language, English, and sometimes not that well.  But I used the
language tool at
and pasted the URL into the http:// field
under ''Translate a web page''.  Although the translation is rough,
sometimes laughable, considering that a mere AI machine did this the
result is pretty impressive, and you can definitely understand
Joaquin's fine writing.  Check it out.  This is really a great blog
about amateur radio with impressive photos and other graphic images.

Dave Fisher, KA2CYN of New City, New York, says that during last
week's contest on 10 meters, October 26 with a roof-mounted
rotatable multi-band trap dipole he worked a number of South
American stations, the furthest ''in Brazil and Argentina''.  He
wonders if it could be F2 propagation, but this was probably E-skip.
W7FA (see last week's bulletin ARLP044) reports more 10 meter
propagation from Oregon, on October 22, 2100-2130z, a short opening
to LU and PY, just like KA2CYN a few days later.

So what does the upcoming week hold?  I don't know how long this new
sunspot will remain.  According to the U.S. Air Force and NOAA Space
Weather Prediction Center, planetary A index is predicted at 8 for
October 31, then a nice low index of 5 for November 1-6.  But
November 7, look for a big geomagnetic upset, complete with more
absorption on HF, especially over polar paths, with a planetary A
index of 35.  But this may also give VHF operators some nice auroral

The same forecast does not predict sunspot numbers, but solar flux,
which has been right around 67 since October 26.  They predict solar
flux at 69 for November 1-6, then 70 for November 7-12.

Geophysical Institute Prague predicts ''Relative sunspot number in
the range 0-25'' for October 31-November 6.  They forecast unsettled
geomagnetic conditions for today, October 31, quiet to unsettled
November 1, quiet conditions November 2-5, and quiet to unsettled
November 6.

It is possible that around November 4 we may see a return of sunspot
number 1005.

Just before this bulletin was released, Joaquin EA2CCG wrote: I
worked WH2P at 0937z 29 October''.

''Today 31 October we also have good conditions...and a Surprise. On
this moment at 1647z listening to LU on 15 meters. This morning I
worked VU7NRO on 15 meters, weak but workable. Suddenly 10 meters
were also opened, listening to some European beacons. At 1111z I
caught a sporadic-E opening on 6 meters and worked 8 European
stations from OK, DL, OE and 9A.  What a day.''

So the ''wager'' about 0900z turned out to be not far off.  This was
done looking at W6ELprop, assuming one sunspot.

Also, Jim Henderson, KF7E in Arizona says ''VU4MY was actually
workable on 14.240 MHz this morning.  Good sign.''  Local morning for
Jim might be 1300-1700z.  Jim also reported some 17 meter long path
propagation to a station that turned out to be a fake, so he doesn't
really know where it was.  He wrote, ''Back in early 1972 there was a
guy signing ZK2 something, with the name of 'Back' or 'Bach'. He
would show up every other week or so''.

''In about July of that year I found myself on Niue as ZK2DX (the
original issue of that call). On one of my first nights operating,
there was ZK2?? with a grand pile on 20m.''

''I would have loved to have seen his face when I called him and said
'Please tell me where on the island you are because I would love to
come visit your shack'.

''He vanished forever.''

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

Instructions for starting or ending email distribution of this
bulletin are at

Sunspot numbers for October 23 through 29 were 0, 0, 0, 0, 0, 0, and
0 with a mean of 0.  10.7 cm flux was 67.2, 67.5, 67.5, 66.9, 67,
67.1, and 66.7 with a mean of 67.1.  Estimated planetary A indices
were 3, 2, 1, 4, 1, 4 and 11 with a mean of 3.7.  Estimated
mid-latitude A indices were 3, 0, 1, 3, 1, 5 and 16 with a mean of


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