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ARRL Propagation Bulletin ARLP051 (2004)

ARLP051 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 51  ARLP051
From Tad Cook, K7RA
Seattle, WA  December 10, 2004
To all radio amateurs 

ARLP051 Propagation de K7RA

This weekend is the ARRL 10-Meter Contest. Conditions aren't great
at this point in the solar cycle, but this can be a fun single-band
operating activity. Unfortunately, we may see a recurrence of some
unsettled to active geomagnetic conditions from the last solar
rotation. The predicted planetary A index for December 10-13 is 8,
20, 30 and 12, so that suggests some rough conditions on Sunday.
The predicted solar flux for those same days is 85-90, with the
values rising gradually and peaking around 105 from December 22-25.

Average daily sunspot numbers for this week were 46, down from 55.1
for the previous week. Average daily solar flux dropped nearly 14
points to 97.

We received mail concerning K5SWW's 10-meter observation of
Scandinavian CW signals mentioned in last week's Propagation
Forecast Bulletin, ARLP050.

Joe Clayton, W2REH wrote: "This 'Scandinavian Express' opening is
not unusual at all. There were signals here in South Jersey around
2100z from SM, OH etc on 10 and 15. Some were a little raspy,
suggesting a bit of aurora, I guess. This is a regular opening that
we tend to look for in the contests in the afternoon, particularly
if someone needs a northern multiplier like JW, or is short a
Scandinavian mult on 10 or 15."

Bill Hohnstein, K0HA of Seward Nebraska has been looking at this
propagation for the past couple of months by listening for beacons
from Scandinavian countries. He copied the OH5RAC beacon on 28.231
MHz at 1957z on November 28. He received an email from OH6IY, who
operates the beacon, reporting that Bill's was the first reception
report from outside Europe. The beacon operates at 4.5 watts from a
modified British paging transmitter hooked through 30 meters of
RG-213 to a dipole on a water tower. OH5IY says the radiation toward
the United States is very low due to the dipole orientation and the
low height off the tank roof.

OH5IY wrote: "The propagation is 'post-Auroral,' the Au ended here
some hours ago and I am surprised to note the sigs get to USA. The
antenna is a dipole with ends pointing to AZ 300 degrees, so there
is several minima to east coast, but the skewed Au paths have
allowed the propagation from the northern lobe to you."

Bill thinks the propagation from his end may be a first hop via F2,
with a trans-equatorial-like spread F-hop after that. Check out
Bill's impressive antenna farm on the site by
looking up K0HA.

John Laney, K4BAI has noticed the same loud Scandinavian signals on
both 10 and 15 meters, often after openings to the rest of Europe
have been closed for a couple of hours. He thinks this is more often
observed during major DX contests, because more Scandinavian
stations may be on during those times. Chip Margelli, K7JA wrote,
"That's the usual afternoon OH/SM/LA/UA1Z opening that is more
commonly observed on 21 MHz. Sometimes it does extend up to 28 MHz,
and indeed the Scandinavian side is always in darkness."

Joe Schroeder, W9JUV wrote that he observed the same propagation,
but on both days of the CQ World Wide when he was running QRP. When
European signals started to fade, he worked OH, SM and UA1 stations.

W3DF, W9DY, and N5AW also sent in similar remarks about the late 10
meter propagation to Scandinavia.

Ken Brown, N4SO wrote to remind us that there is a log of current or
recent WWV solar flux and mid-latitude K and A index data on the site.

If you would like to comment or have a tip, email the author at,

For more information concerning propagation and an explanation of
the numbers used in this bulletin see the ARRL Technical Information
Service propagation page at,

Sunspot numbers for December 2 through 8 were 62, 58, 43, 46, 47, 26
and 40 with a mean of 46. 10.7 cm flux was 105.6, 100.8, 97.4, 95.9,
93.2, 89.7 and 96.5, with a mean of 97. Estimated planetary A
indices were 4, 3, 1, 8, 19, 15 and 10 with a mean of 8.6.
Estimated mid-latitude A indices were 4, 1, 0, 7, 11, 9 and 9, with
a mean of 5.9.


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