ARRL

ARRL Propagation Bulletin ARLP029 (2009)

SB PROP @ ARL $ARLP029
ARLP029 Propagation de K7RA

ZCZC AP29
QST de W1AW  
Propagation Forecast Bulletin 29  ARLP029
From Tad Cook, K7RA
Seattle, WA  July 17, 2009
To all radio amateurs 

SB PROP ARL ARLP029
ARLP029 Propagation de K7RA

We saw a nice run of eight days with a large sunspot, but none have
emerged in the six days since.  Unlike other recent spots, this one
did not appear just for one or two days, then vanish.

Check the data at http://www.swpc.noaa.gov/ftpdir/indices/DSD.txt
and note the Sunspot Area, expressed in millionths of a solar
hemisphere, which kept growing after the daily Sunspot Number peaked
at 26.

The solar flux dropped below 70 on July 9, two days before the
disappearance of this latest spot, and it has stayed there since.
Solar flux is expected to rise to 70 or above July 25 through August
5.  The same 45-day forecast at
http://www.swpc.noaa.gov/ftpmenu/forecasts/45DF.html (I am looking
at the July 16 forecast) predicts continued quiet and mild
geomagnetic conditions, with planetary A index of 5.  The only
predicted larger values we see for the next few weeks are 10 on July
21, 8 on July 28-29, and 8 and 7 on August 5-6.  This is a wonderful
aspect of the weak solar wind, which does not play havoc with
propagation as it does during stormier times.

Geophysical Institute Prague predicts quiet conditions for July
17-20, unsettled July 21, quiet to unsettled July 22, and back to
quiet on July 23.

Many of us have been longing for the days of daily sunspot numbers
above 100, but there was a downside, and that was from heightened
geomagnetic activity.  While this could be nice for VHF operators
wishing to aim their beams north and refract their signals off of
aurora, for everyone else, especially those at higher latitudes, the
effect on HF was not a good one.

I was looking in old issues of our propagation bulletin for
examples, but found that our archive online only goes back to
January of 1995, and we didn't begin recording any geomagnetic
numbers until October 1996 when it was suggested by Robert Wood,
WB5CRG (now W5AJ).  It began with just the planetary A index in
ARLP042 on October 11 (see
http://www.arrl.org/w1aw/prop/1996-arlp042.html).

But looking back in bulletins from 1997 and especially 1998, we can
see geomagnetic indicators that could wipe out HF communications for
days at a time, causing some operators to believe that their radio
was broken or feedline was cut.

Go to http://www.arrl.org/w1aw/prop/ and click on the ''Show older
bulletins'' link toward the upper center of the page.

Any time the A index is above 15, conditions may begin to get rough.
For 1997, check the bulletins numbered 40, 42, 44, 46 and 48.  Note
that on some days, the planetary A index could get into the mid or
high twenties, or even worse, the forties or sixties.  ARLP048 from
1997 describes a severe geomagnetic storm.

Conditions became tougher in 1998.  For that year, check out
bulletins 13, 18, 19, 27, 30-33, 35, 36, 40, 43, 46 and 47.  Some
days had planetary A index readings of 48, 52, 60, 69, 78, 96, 112
and even 121.  This made HF conditions tough all over, but talk to
someone who was trying to operate from Alaska in 1998.  Ketchikan is
above 55 degrees North latitude, and Juneau above 58, but Anchorage
is above 61 degrees, and Fairbanks, nearly 65 degrees north
latitude, about 120 miles south of the Arctic Circle.  The further
north you are, the more pronounced are the effects of geomagnetic
disturbances.

So enjoy this weak solar wind.  It wasn't always like this.

Bob Leo, W7LR of Bozeman, Montana has worked with radios for many
years.  He is 88 now, and you can see his bio at
http://www.qrz.com/w7lr.  Bob reports a personal first on July 9
when he heard Europe on 6 meters, which he says is new and exciting.
At 1356z on 6 meter CW he spent a half hour working CT1HZE
(Portugal) with strong signals.  Bob was running 100 watts into a
7-element Yagi at 45 feet.

Bill Gannaway, a reader in Greenville, Texas experienced some
dramatic sporadic-E skip on July 10.  Around 2200z Bill was driving
home from work, and trying to listen to a strong local station when
it was covered over by a station in Tucson.  He tuned up the dial,
and found a number of Phoenix and Tucson stations all up the band.
A useful tool for identifying broadcast stations by frequency,
location and callsign, is http://www.radio-locator.com/.  Click on
Advanced Search.

Robert Forsman, WK5X of Stuart's Draft, Virginia reports an
interesting six meter experience on July 6.

''I've often wondered about what the shortest possible single-hop
distance would be on 6 meter sporadic-E.  Until the opening of July
6 of this year, my personal shortest QSO via 6 meter sporadic-E was
just a bit longer than 300 miles.  During these types of openings, I
work grid squares that are otherwise difficult''.

''Around 2300z on July 6, my XYL informed me (I was in the other end
of the house) that my FT-897D, which I had accidentally left on, and
parked on 50.095 MHz, was ''beeping loudly'' and that I needed to ''go
turn that thing off''.  I thanked her for alerting me to the band
opening''.

''I'm not used to hearing 8's on 6 Meters.  From my QTH in Virginia's
Shenandoah Valley, most of the 8's that I've worked have been either
in the Upper Peninsula of Michigan, or a mountaintop contest station
in nearby West Virginia.  After settling at the rig, the first
station that I worked was KA1VHF, near Columbus, OH.  The second
station that I worked was KA8HOK, Millersport, OH at a distance of
only 234 miles.  This was my shortest ever sporadic-E QSO.  I also
noted that these were some of the strongest non-local signals that
I've ever heard on this band.  A quick look at EA6VQ's estimated MUF
real time map indicated that the estimated E-layer MUF at the
midpoint between KA8HOK and myself was 303 MHz.  I believe that that
is the highest I've ever seen on 'VQ's real time map.  Hopefully
someone was able to take advantage of this on 1.25 Meters''.

''Then, as the MUF over the region began to fall, the band grew
longer.  My next contact was with northern Indiana, and then my next
two were in southern Michigan''.

The EA6VQ tool that Bob refers to is at
http://www.vhfdx.net/spots/map.php.

From July 8, Steve McDonald, VE7SL of Mayne Island, British Columbia
sent this in.

''Just a note to tell you of some truly great propagation this past
week on the magic band.  Early on the morning of July 8 I had been
chatting with Jack, OA4TT (140 km south of Lima Peru) on the ON4KST
50 MHz chat page.  As everyone tends to do when propagation is slow,
we were jokingly describing what it might take to get a signal from
OA to VE7 on multi-hop Es.  I posted that we needed the link to UT
or Southern CA/Arizona, then into Mexico, Oceanic next and finally
another hop down to Lima.  As we mused, I was hearing strong
single-hop into Utah.  I left the shack for about an hour only to
return to see that Jack had decided, just for fun, to send a few CW
CQ's towards the USA on 50.1155.  With little expectation, I moved
the receiver down to Jack's frequency and immediately heard him
calling CQ.  After picking myself up from the floor, I gave him a
short call to which he immediately responded.  Signals were weak
(449) and somewhat watery and fluttery which leads me to think that
this was something other than multi-hop Es.  At something over 5,000
miles, this mid-summer contact demonstrated why the 'magic' band
continues to live-up to its name''.

Check Steve's web page, the VE7SL Radio Notebook:
http://members.shaw.ca/ve7sl/

Martin McCormick, WB5AGZ of Stillwater, Oklahoma offered some very
interesting comments on TV channels 2-6 after the digital TV
transition.

''Central Oklahoma is now devoid of local signals between 54-88 MHz
and the listening is interesting.  Sunday July 12 was the last day
of the ''Nightlight'' service that Congress authorized so that one TV
station in each market could keep an analog transmitter going with a
loop to tell the 1 or 2 people who hadn't figured it out yet what
needed to be done to receive TV over the air.

KOCO Channel 5 in Oklahoma City was the last full-power analog to go
dark there and Monday July 13 saw a moderate Es opening with Spanish
language TV probably from Mexico fading in briefly around 17:00 UTC
on 81.75 MHz.

A couple of propagation Observations:

We have had several days this year in which Mexican signals reached
as far up as the low end of the FM Broadcast band.  When that
happened, TV Channels 2-6 were full of Spanish and sometimes English
and French from Canada.

In a QST article of a couple of years ago, someone mentioned that it
would be nice to see if we can get the 72-76 MHz band for North
America.  The services there now could move to an equal amount of
space in one of the vacated TV channels and make this an interesting
DX band.

A couple of weeks ago, I had left a receiver tuned to TV Channel 4
at 71.75 MHZ.  We have had very hot summer days and the tropo at
night has been fairly impressive.  Instead of Es, I got literally
hours of a Channel 4 television audio signal from somewhere within
the central US.  It was running the endless loop nightlight service
with no aural ID so I don't know where it was, but it didn't fade
out until after Sunrise at which time it went away fast.  One can
guess that 6 meters and 72 MHZ would have been hot during that
night.

It is strange to spin the dial on a general coverage VHF receiver
now and not hear the buzz of video and FM audio landmarks that were
there since before many of our births, but Canada and Mexico will
provide good propagation beacons for a few more years to come.

I believe it was February QST where I read that 37 US broadcasters
will keep their new digital signals on Channels 2-6. I wonder for
how long and how many Es openings it will take to change their
minds''.

Thanks, Martin.

Jeff Lackey, K8CQ of St. Simons Island, Georgia writes:

''Six meters has been great as you have been commenting in your
weekly solar update.  And I had to tell you that even ''lousy
antennas'' can work, such as my 15 ft flag pole that I use mostly on
HF.  But as a joke I found it would load up on 6 meters a couple of
years ago.  Over the last couple of weeks, I've made about 100
contacts on 6m in 19 states and 6 DX entities.  Yesterday (15 July
2009) at 2050Z I worked CT1HZE.  He was S5 when I worked him, but
later he peaked to S8 working many NA stations.  That was my first
European QSO on 6m.  Earlier around 2000Z I had heard EA8AK (S8)
working into Spain.  He didn't hear me.  I heard several EU stations
but all too weak to make contact.

So I am now up to 37 states and 13 DX entities on 6 meters with my
flag pole antenna.  I encourage others in CC&R situations to get on
and try out this ''magic band.''  It is a lot of fun when Es band
conditions exist.  The beacons below 50.080 are a great help in
knowing if the band is open.  And don't be afraid to call CQ.  I
have done this many times when the band for me seemed dead.  Every
once in awhile I am surprised to get a response''.

Don't forget the CQ World Wide VHF Contest this weekend.

See http://www.cqww-vhf.com/ for details.

If you would like to make a comment or have a tip for our readers,
email the author at, k7ra@arrl.net.

For more information concerning radio propagation, see the ARRL
Technical Information Service at
http://www.arrl.org/tis/info/propagation.html.  For a detailed
explanation of the numbers used in this bulletin, see
http://www.arrl.org/tis/info/k9la-prop.html.  An archive of past
propagation bulletins is at http://www.arrl.org/w1aw/prop/.

Monthly propagation charts between four USA regions and twelve
overseas locations are at http://www.arrl.org/qst/propcharts/.

Instructions for starting or ending email distribution of this
bulletin are at http://www.arrl.org/w1aw.html#email.

Sunspot numbers for July 9 through 15 were 15, 13, 0, 0, 0, 0, and 0
with a mean of 4.  10.7 cm flux was 69.1, 67.8, 68.2, 68, 67.2,
66.6, and 66.5 with a mean of 67.6.  Estimated planetary A indices
were 6, 7, 4, 5, 10, 8 and 5 with a mean of 6.4.  Estimated
mid-latitude A indices were 6, 7, 2, 4, 5, 6 and 3 with a mean of
4.7.
NNNN
/EX