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ARRL Propagation Bulletin ARLP040 (2005)

ARLP040 Propagation de K7RA

QST de W1AW  
Propagation Forecast Bulletin 40  ARLP040
From Tad Cook, K7RA
Seattle, WA  September 23, 2005
To all radio amateurs 

ARLP040 Propagation de K7RA

Solar activity quieted down this week after a recent tumultuous
period marked by aurora and geomagnetic storms. Average daily
sunspot numbers were down over 25 points from the previous week to
46. Average daily solar flux declined by over 9 points to 100.3.

Sunspot numbers are expected to stay low, rising again after October
3. Geomagnetic conditions should also stay low, with unsettled
conditions possible around September 27-29. Geophysical Institute
Prague predicts quiet to unsettled conditions September 23-24, quiet
on September 25-26, active conditions September 27, and unsettled
conditions September 28-29. Autumn has now begun, and despite the
low solar activity, conditions are more seasonally favorable for HF
propagation. The lower geomagnetic activity is a plus for HF

We received more mail on 80 meter propagation at the bottom of the
solar cycle. David Beckwith, W2QM of Delray Beach, Florida believes
that "seemingly better conditions during the low point of the cycle
may be due more to more activity because the higher bands are so
poor." Good point! David should know. He's been on the air since
1938--even during World War II, when he was an infantry radio
operator in Europe. According to his bio at he has worked 380 countries,
including all except North Korea on the current DXCC list.

Ed Douglass, AA9OZ wrote in again about 80 meter propagation, this
time mentioning the John Devoldere, ON4UN book, "ON4UN's Low-Band
DXing." Ed writes, "ON4UN's explanation for good propagation on 80
and 160 during sunspot minima is that with less solar UV radiation,
there is less density in the D-layer in the earth's atmosphere.
Furthermore, the formation of the D-layer is slower, particularly
during the winter months in either hemisphere.

He continues, "As you know, it is the D-layer that tends to absorb
lower HF signals, most notably preventing the propagation of signals
during local daylight hours. So, in addition to your explanation
that a less active sun will produce less intense disturbances in the
ionosphere and therefore propagation through the auroral zones will
be better, propagation on East-West paths will be better because
there will be longer periods when there is no D-layer.

Ed goes on to say, "Devoldere goes into this much more thoroughly so
his book is worth understanding and following if one is serious
about DXing on the lower bands. And, as thunderstorm activity drops
in the northern hemisphere as we go into winter, the weaker DX
signals can once again be heard."

John Shannon, K3WWP, wrote, "I run 100% CW and 100% QRP here. My
antenna for 80 and 160 is a random wire in my attic. In the two big
160M contests, ARRL and CQ, with my simple setup it was fairly easy
for me to work around 250 QSOs during the sunspot minimum back in
the 90's. That included working WC USA stations. At sunspot maximum
I had to STRUGGLE to make 50 or 60 QSOs and usually gave up out of
frustration at no one hearing me or having to repeat my info many
times over to virtually every station. I couldn't work anyone west
of the Mississippi River at the maximum. On 80 meters I can usually
work EU near the minimum but it is rough near a maximum.  So based
on personal experience, I would say low band conditions are
definitely better at or near a minimum."

John has a personal web site devoted to his ham radio interests at,

Russell Hunt, WQ3X wrote in to say that he is still working DX on 10
meters. He writes, "Last night (9/15/05) on 10M SSB I worked CN8KD,
CT4GO and EA1CBX starting at 2200Z. Local time over there was 11PM!
Signals were amazingly strong but the opening only lasted about a
half hour. It was incredible! I was able to hear most of the USA
stations working the DX also."

I ran some path projections using a popular propagation program
mentioned in past bulletins, and found that from his location in
Pennsylvania to Spain, Morocco and Portugal there is still good
likelihood of 10 meter openings ending around the time John made his
contacts. On the web, be sure to check out John's web site devoted
to some work he's done refurbishing classic radio gear at,

Last, we hear from Bill Clark, N0MAM. He writes, "I became licensed
in 1996 when many experienced hams were complaining about the bands.
At that time I had the call KB0TNM. I began working 40 meters on the
novice CW band and many experienced hams complained that it was too
noisy a band to work. I was on every night making domestic contacts.
I worked 30 states that summer and winter, mostly eastern and
western states.

He continues, "I worked Hawaii, Alaska, Mexico, and many Canadian
contacts.  It put me well on the way to getting WAS 40 Meter CW. I
didn't know what all the complaints about 40 meters being noisy were
about until 1998 when the bands came up and all the Latin American
AM stations created so much whine that I had to abandon. It was a
lot of fun and good experience for me as a new operator and I didn't
even know that I wasn't supposed to be enjoying myself because the
band was 'down."'

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

For more information concerning radio propagation and an explanation
of the numbers used in this bulletin see the ARRL Technical
Information Service propagation page at, An archive of past
bulletins is found at,

Sunspot numbers for September 15 through 21 were 77, 51, 59, 50, 43,
23 and 19 with a mean of 46. 10.7 cm flux was 119.4, 112, 103.9,
102.2, 91.1, 87.8, and 86, with a mean of 100.3. Estimated planetary
A indices were 43, 18, 12, 12, 8, 6 and 5 with a mean of 14.9.
Estimated mid-latitude A indices were 22, 11, 10, 8, 8, 3 and 3,
with a mean of 9.3.


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