ARRL Propagation Bulletin ARLP006 (2008)

ARLP006 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 6  ARLP006
From Tad Cook, K7RA
Seattle, WA  February 8, 2008
To all radio amateurs 

ARLP006 Propagation de K7RA

After a solid week of sunspots (January 29 to February 4), the
following three days have been blank.  February 2 was an active
geomagnetic day, with a solar wind stream spewing from a coronal
hole near sunspot 982.

Another solar windstream from a coronal hole is expected to strike
Earth on Sunday, February 10, causing unsettled conditions.  The
predicted planetary A index for February 8 through 15 is 8, 12, 15,
10, 10, 10, 10 and 5.  That was from NOAA and the U.S. Air Force,
and Geophysical Institute Prague predicts unsettled conditions
February 8, unsettled to active February 9-10, and unsettled again
on February 11-14.  The Australian Space Forecast Centre's
geomagnetic forecast expects mostly unsettled to active conditions
with storm periods possible at high latitudes on February 9, and
mostly unsettled with isolated active periods and storm levels at
high latitudes on February 10.

Following this weekend, NOAA predicts the next active conditions
around February 28-29. Their prediction for solar flux is flat at 70
for each of the next 45 days, and this probably indicates little or
no sunspot activity.

Bob Leo, W7LR of Bozeman, Montana and IS0/YO3RA (Sardinia) have been
trying for several years to make contact on 160 meters.  Bob claims
228 countries on 160, but says Sardinia seems to be ''a black hole'',
even though both have what he calls ''reasonable stations'' for that
band.  With some acreage for antennas, Bob runs full power, has
various receiving antennas pointed toward different directions, and
even a two-element transmit array toward Europe with 4.5 db gain.

He asked what time would be best to work Sardinia on 160, and
frankly, I didn't know, except I would expect darkness at both ends
of the path when successfully making contact.  The propagation
modeling programs generally don't work below 3 MHz.  I noted that
this weekend darkness should extend over both locations from
0036-0629z, or at least the sunset in Bozeman will be 0036z and
sunrise in Sardinia is at 0629z.  Bob emailed back, and said he
finally heard YO3RA at 0510z.  He hopes to work him this season
before YO3RA departs Sardinia on February 15.

Several readers wrote to ask about the recent sunspot mentioned in
last week's bulletin, hoping it was a cycle 24 spot.  Alas, sunspot
982 had cycle 23 polarity.  Any cycle 24 spots in the near future
will be reported here.

Stan Tacker, N5OHM of Tulsa, Oklahoma writes that the absence of
sunspots and geomagnetic activity is great for 160 meters, but
creates problems for AM broadcast stations.  He operates one in
Northeast Oklahoma on 1.57 MHz (which is 191 meters), and that is a
portion of the AM broadcast band where stations run low power,
sometimes 250 watts during the day, and as little as 6-8 watts at
night.  There is also a Mexican ''border blaster'' station on this
frequency, and his station is experiencing QRM well into mid to late
morning, hours after sunrise.  Stan's station is running 1 KW, and
broadcasting in the daytime only.

Chuck Zabriskie, KE5HPY in Houston, Texas wrote on February 2 that
the 60 meter shortwave broadcast band (4.4-5.1 MHz) was jumping on
January 29-31 from 0300-0500z.  He heard African stations ''that
rarely rise above the noise at this QTH''.  He copied Angola,
Madagascar, Chad, South Africa, Swaziland and Botswana, all as loud
as Midwest AM broadcast stations.

Regarding the 60 meter ham band, check out a web page devoted to
that band 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 January 31 through February 6 were 15, 19, 16,
14, 14, 0 and 0 with a mean of 11.1.  10.7 cm flux was 72, 71.1,
71.8, 71, 71.3, 70.5, and 71.6 with a mean of 71.3.  Estimated
planetary A indices were 5, 18, 19, 12, 6, 3 and 4 with a mean of
9.6.  Estimated mid-latitude A indices were 3, 10, 19, 10, 6, 2 and
2, with a mean of 7.4.