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ARRL Propagation Bulletin ARLP017 (2011)

ARLP017 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 17  ARLP017
From Tad Cook, K7RA
Seattle, WA  April 29, 2011
To all radio amateurs 

ARLP017 Propagation de K7RA

Geomagnetic conditions are quiet this week, but may become slightly
unsettled over this weekend.  Average daily sunspot numbers were
down over 18 points to 74.9, while average daily solar flux was off
less than four points to 113.4.

Predicted solar flux values for today and tomorrow, April 29-30 are
110, May 1-8 is 105, 110 on May 9 and 115 on May 10.  The next peak
in solar flux is May 11-13 with a value of 120.  This is actually
higher than the flux values over the last month, except for one day,
April 15, at 129.  Over the last three days five new sunspot groups
emerged. Daily sunspot numbers fell over April 22-27, then rose to
71 on April 28.

Predicted planetary A index for April 29 to May 3 is 5, 10, 12, 10
and 8, then 5 on May 4-7, then 8, 15, 15, 7 and 5 on May 8-12.  So
the two periods in the short term with unsettled to active
geomagnetic conditions are May 1 and May 9-10.

Geophysical Institute Prague predicts quiet conditions on April 29,
unsettled to active on April 30, unsettled May 1-2, quiet to
unsettled May 3, and quiet May 4-5.

Angel Santana, WP3GW of Trujillo Alto, Puerto Rico feels that the
good old days are back for twenty meters.  He wrote, "On World
Amateur Radio Day at 0304-0630 UTC on 20 meters, worked 22 stations
from Europe and the Pacific, including VK, ZL, FO and NH7 all on SSB
(and so on to get my WARD Award). When working Europe it looked like
it was 3-4pm local time, something I have not experienced for a long
time! Then on this past holiday weekend I deliberately lost sleep to
see how the band was, and it worked the same way: worked a P29, SV1
and a few more Europeans, and also looking at PSK31, wow, seeing the
same activity, something not seen two months ago. Propagation is
really turning on, making 20 meters the 24 hour band again. Plus on
Easter Day at 0845 UTC worked T31A in 40 meters, a new DXCC country
for me! Right now at 0850 UTC April 26th I am hearing ON4UN working
lots of VKs."

Rol Anders, K3RA of Elkridge, Maryland (southwest of Baltimore) also
likes 20 meters lately.  He wrote, "On Easter Sunday morning (April
24), there was an excellent long path opening on 12 meters to VR2
and BV from 1200-1230z. I worked VR2XMT on phone with my antenna on
the long path, then tuned down to CW and heard BU2AQ working Asiatic
Russians and Eastern Europeans. He was moderately strong and very
solid. I could not hear the stations he was working, but they were
all given 599 reports by BU2AQ. I heard no other USA stations
calling him for the first 10 minutes or so. A PY was trying,
unsuccessfully, but neither he nor I could break the Asia/Europe
'wall.' Eventually several other stations in the US heard him, but
we all failed to break through. He started to fade at 1225z in
Maryland. However, around 1230z, some W8s and W4s got through, and
he worked a number of them, but by that time he was very weak in

"Also, I am hearing a return of the LP on 20 to SE Africa around
1200z. I haven't heard that opening for years.

"Isn't it great to have 20 meters being an all-day DX band again?"

Rich Dowty, W7EET of St. Paul, Oregon sent info on an interesting
tool called "PSK Reporter."  See the web site at and also their map utility at The map displays stations using
digital modes on HF who are tied into the reporting network. The
user can click on any of the balloons to display a callsign for a
monitor at that location, then enter that call in a query above the
map to display all the stations that it could hear over a specified
period of time. You can also click in the balloon on "Show all seen
by" link.  With the ability to check links on different bands and
over different time periods, this is an interesting and useful tool
for observing HF propagation.

There are some interesting videos showing use of this tool at,, and

Last week's Propagation Forecast Bulletin ARLP016 mentioned Bud
Trench, AA3B of Boyertown, Pennsylvania.  At you can see some detail on his radios and
antenna system.

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 April 21 through 27 were 100, 103, 80, 78, 67,
57, and 39, with a mean of 74.9. 10.7 cm flux was 113, 114.8, 119.1,
117.2, 112.1, 109.4, and 107.9, with a mean of 113.4. Estimated
planetary A indices were 5, 6, 6, 6, 6, 3, and 3, with a mean of 5.
Estimated mid-latitude A indices were 4, 3, 4, 6, 2, 1, and 0, with
a mean of 2.9.


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