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Propagation de K7RA

31 January, 2009
ARLP005

In last week's Propagation Forecast Bulletin ARLP004, we did not have the solar flux values resolved down to a tenth of a point like we always do. Really, resolving the solar flux down to that resolution is probably not very useful, but for those who use the WA4TTK solar plotting program to suck up the data and who are compulsive enough, here are the values for January 15-21, so you can correct your data: 71.1, 70.8, 71.9, 71.1, 70.8, 70.4, 69.4, with the mean value at 70.8.

On Tuesday, January 27 we saw another one of those "almost-a-sunspot" emerge in the Sun's low latitude, so it was probably an old Cycle 23 spot. The next day it was gone.

Geomagnetic conditions continue to be very quiet, although a bit unsettled on January 26. The forecast is for more of the same.

Planetary A index should stay around five, and solar flux around 70. Geophysical Institute Prague predicts unsettled conditions for January 30, quiet to unsettled January 31, and quiet February 1-5.

This week we received one report about last weekend's CQ WW 160 Meter CW contest. Rod Swiderski, NU2M of Watermill, New York, reported that band conditions were outstanding. He writes, "I worked 13 countries, 47 states, my first Alaskan station KL7RA (on 160) and 320 contacts. All with a mere 100 watts and a 160 dipole at 35 feet. I find it simply amazing how that band only appears 'open' during a contest."

Floyd Chowning, K5LA of El Paso, Texas wrote about excellent conditions on 6 meters on Sunday, January 25. He had just put up a new 5-element antenna, and said, "This morning I was running JT6M contacts with K7JIZ (DN40) and W6OUU (DN22) around 1541 UTC and signals were strong and steady. It must be sporadic-E skip. From then on the band opened up to California, Arizona, New Mexico, Texas, Louisiana, Missouri, Florida and Iowa. Also, I heard a KP4 in Puerto Rico this morning but missed his call. This afternoon I worked several stations in Mexico in EK09, DK89 and DL90 beginning around 2040 UTC. I also worked TI7/N5NEK (EK70), TI8II (EJ01) and YN2N (EK71). I worked all the stations on USB. What a day for DX on 6 Meters. I also heard HP1AC on CW but did not work him. I heard stations as close as Albuquerque, Phoenix, and Odessa, Texas, less than 300 hundred miles. I had my radio on 144.2 MHz but nothing broke my squelch."

Floyd mentioned JT6M, which is a tool for running meteor scatter communications. For more about JT6M, see http://www.jt6m.org/.

This week I received a copy of a remarkable old letter, sent by Jim Mast, W8HOM, of Fort Wayne, Indiana. It was written on the last day of 1975 by Ed Tilton, W1HDQ, the ham who originated the ARRL Propagation Bulletin and wrote it until 1991. This letter was addressed to Jim back when his call was K9UNM. The letter talks about 10 meter propagation via meteor scatter and the recent 1975 ARRL 10 Meter contest. It mentions W4IWZ, the call sign that belonged to Francis Harper, of Nokesville, Virginia. The letter was typed on an old manual typewriter.

Here is what the letter said.

Dear Jim:

We certainly have heard of 10-meter meteor propagation. The date of the contest was chosen with the Geminids shower in mind. This best of the winter showers has been a factor in the contest results for all three runnings of the affair in "modern" times.

I think the 1975 contest may have hit the shower at the most opportune time, as the effects seemed very apparent almost continually during the whole weekend. The Geminids show more night-time activity than any other shower, but there seemed to be a considerable amount of meteor burst propagation right through the whole period this year. There is always a tendency to have E propagation in mid-December, and this was also a factor in the date selection. I hope that the propaganda some people have generated for a change of season does not prevail. To my mind, this is an excellent choice.

For some reason I didn't get to work W4IWZ in this contest. He and I used to be in touch almost daily, when I was at home every day, in 1973 and early 1974. I guess we've worked by means of about every form of propagation there is, at one time or another, and have seen the effects of several meteor showers. At slightly over 300 miles, he is at a very interesting distance from me. We have found that we always have a basic tropo-scatter signal, and can recognize each other on CW at almost any time. He has at least a 10-dB advantage in power, but somehow he manages to hear me every time I call him.

Needless to say, I read him better than he reads me, with my 4O watts output, maximum, we have had many good QSOs, by back-scatter and short sporadic-E skip. His signal is mildly affected by tropospheric bending, too, though I'm sure we'd get more of that on higher frequencies. We see every kind of ionospheric effect on this path, at one time or another, and have had many backscatter QSOs, from many different directions.

Meteor ionization, being an E-region phenomenon, is very common on 28 MHz. The only reason why I can account for the unawareness of it on the part of many 10-meter buffs is that most of them tend to disregard weak signals, or they expect the band to be dead for 3 or 4 years out of every 10. You can hear meteor bursts any morning, 365 mornings per year, on 10. Keep morning skeds for a while, with people at distances where the direct signal is weak, and you'll hear them much better than on 144 or even 50 MHz. During major showers they even give the impression that that band is 'open'-- which it always is, anyway. Ask Harper - he'll tell you that!

vy 73

Ed Tilton, W1HDQ

I thought this letter was so interesting and timely, considering recent discussions about meteor scatter propagation on HF, that it should run here in its entirety. Thanks, Jim, for hanging on to it for 33 years, and sharing it with us.

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 web page 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 January 22 through 28 were 0, 0, 0, 0, 0, 0, and 0 with a mean of 0. 10.7 cm flux was 69, 70, 68.8, 69.8, 69.9, 69.7, and 69.5 with a mean of 69.5. Estimated planetary A indices were 1, 1, 1, 1, 10, 4 and 2 with a mean of 2.9. Estimated mid-latitude A indices were 0, 1, 1, 1, 9, 2 and 1 with a mean of 2.1.

Source: The American Radio Relay League

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