Register Account

Login Help

ARRL Propagation Bulletin ARLP003 (2010)

ARLP003 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 3  ARLP003
From Tad Cook, K7RA
Seattle, WA  January 22, 2010
To all radio amateurs 

ARLP003 Propagation de K7RA

A steady stream of sunspot activity continues to dot the Sun.  We
had just one day with a daily sunspot number of zero this week,
January 19 (Tuesday) when sunspot group 1040 moved over the horizon.
But the next day old sunspot group 1039 re-emerged as 1041, and it
now graces the Sun's southeast (lower left, relative to our view
from Earth) quadrant.  In fact, now that we have a view of most of
the Sun (87.35% as of 2359z today, because of advanced orbiting
instruments) it appears that the sunspot group that just left is
nearly antipodal to the current visible spot, just exiting the Sun's
northwest quadrant.  If they stay strong, when the current one
leaves, the other should return.

The current prediction from USAF/NOAA has the solar flux rising from
Friday, January 22 through Tuesday, January 26, at 84, 85, 85, 86
and 87.  Barring any unforeseen flares, planetary A index is seen as
steady and quiet at five.  Geophysical Institute Prague predicts
quiet geomagnetic conditions January 22-23, quite to unsettled
January 24, and quiet again January 25-28.

A Sudden Ionospheric Disturbance (SID) occurred on Wednesday after a
solar flare.  The IMF (Interplanetary Magnetic Field) between Earth
and the Sun was pointing south.  When it points north, the Earth is
less vulnerable.  You can see a detailed graph of the latest
orientation of the IMF at  See the
graph labeled "Direction of the IMF."  It took me a while to figure
out what the Y axis was for.  I expected it to represent time, but
it seemed to show "meters."  Then I realized it was minutes, and
this record covers the previous two hours.  When that graph goes
above zero, the Earth is protected from the effects of solar flares.
Thanks to Beth Katz of the Space Weather Discussion Forum at for that resource.

A SID will often cause a complete HF radio blackout, the duration
varying with the intensity of the energy from the flare as it (the
energy, not the flare!) reaches Earth.

You can monitor SID events yourself with homemade equipment shown on
a Stanford University web site at,  Note the useful
links provided, which lead to other pages and links, many quite
useful.  Check out and  Thanks to for this tip.

Kermit Lehman, AB1J of Waltham, Massachusetts commented on last
week's Propagation Forecast Bulletin ARLP002: "I have stayed on the
air, refusing to let the good be the enemy of the bad, but it hasn't
been easy.  Since every cloud is reputed to have a silver lining,
even this valley of the shadow of the dearth of Sun spots has been
good for me in some ways.  I was forced to figure out how to get on
40 and 80 on a postage stamp-sized piece of real estate and as a
result worked 5BDXCC, something I would never have tried if there
had been any propagation at all on 15, 12 and 10."

Thanks, Kermit!

Check out K9LA's Propagation column in the current issue of
WorldRadio, available free online at,  Click on the WorldRadio Online
logo on the left side, and see the Propagation column on pages
25-26.  To find the obscure unnamed article he refers to under "Is
there DXing on 4 MHz?," just enter a part of any phrase he quotes
into your favorite web search engine.  When I did it, I got a couple
of hits, but when I clicked the link for "repeat the search with
omitted results included" I saw many more.  Apparently that article
was circulated widely, starting around ten years ago.

In the current February issue of QST in the Up Front section is a
piece about ham radio in the Linux Journal.  What the short item
doesn't mention and isn't in the Linux Journal is the fact that the
founder and publisher is a ham, Phil Hughes, WA6SWR. Phil generously
gave me my first internet access via his company back in the 1980s,
years before the worldwide web.

There is a letter in the same issue of QST from KD4SKB telling about
finding some QSL cards from his Novice days back in 1971.  He
checked on various callsign sites on the internet, and found that
three were from hams who are still licensed, and had email
addresses.  He attempted contact, and got a response from one who
agreed to meet him on 40 meters for a reunion QSO.  He mentioned
that the other fellow was 14 years old when they made contact 38
years earlier.

That reminded me of 1966, when I was 14, and brought my receiver and
DX-20 CW transmitter with me on a Summer visit to my grandparents in
Topeka, Kansas.  I strung up a wire antenna and did a little
operating, and ended up exchanging cards with a fellow in Illinois,
about 300 miles away after a QSO on the 40 meter Novice band.

When I returned to Seattle, after the QSL cards we began exchanging
letters.  He was two years older than me, and for a couple of years
as we passed through those fast-changing stages of adolescence, we
exchanged many letters, sharing the good and the bad, the terrors
and the triumphs of boyhood in the late 1960s.  As I recall, we
shared many things that we likely might not even tell our closest
friends in our home communities.  We talked about radio, girls,
popular music, girls, school and, did I mention girls?

I had a great memory for events, people and minutia for many years,
but now in my fifties it is fading.  For a number of years I have
tried to recall his name or callsign so I could look him up and see
if he were still a ham.  But I couldn't find the logbook from that
summer, and had misplaced his QSL long ago.  But I waited, knowing
that at some time in the future I would recall or see something that
jogged my memory.

Finally last spring it happened.  I was looking through the June
2009 QST, and there he was, Ed Clink, still WA9PFB, still in New
Berlin, Illinois, in the Silent Keys listing.  I finally remembered,
but a little late.  According to FCC records he had renewed his
license just three years earlier, and still had his General Class

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 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 January 14 through 20 were 34, 26, 24, 16, 14,
0, and 16 with a mean of 18.6. 10.7 cm flux was 89.9, 85.3, 84.2,
82.6, 81.5, 84.2, and 81.7 with a mean of 84.2. Estimated planetary
A indices were 4, 3, 1, 1, 3, 1 and 14 with a mean of 3.9. Estimated
mid-latitude A indices were 3, 2, 1, 1, 2, 2 and 6 with a mean of


Instragram     Facebook     Twitter     YouTube     LinkedIn