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Propagation Forecast Bulletin #10 de K7RA:

from W1AW Bulletin via the ARRL on March 8, 2013
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Propagation Forecast Bulletin #10 de K7RA:

Propagation Forecast Bulletin 10 ARLP010
From Tad Cook, K7RA
Seattle, WA March 8, 2013
To all radio amateurs

ARLP010 Propagation de K7RA

The averages of daily sunspot numbers and solar flux over the reporting week (February 28 through March 6) both rose, with sunspot numbers up nearly 36 points to 93.3 and solar flux up nearly 12 points to 112.6, in comparison to the previous seven days. The most active geomagnetic day was Friday, March 1, when the planetary A index was 27 and the mid-latitude A index was 23. Alaska's high latitude college A index was a whopping 64. The upset was sparked by a stream of high speed solar wind.

The latest forecast from NOAA/USAF puts average solar flux for the next five days (March 9-13) at 118.2, higher than average solar flux for the reporting week, which was 112.6.

Predicted solar flux is 112 and 118 on March 8-9, 120 on March 10-11, 118 on March 12, 115 on March 13-14, 105 on March 15, 95 on March 16-17, 100 on March 18-20, 105 on March 21-24, 110 on March 25 through April 1, and 105 on April 2-5.

The predicted planetary A index is 8 on March 8, 5 on March 9, 8 on March 10-12, 5 on March 13-20, 8 on March 21, 5 on March 22-27, then 18, 10, 5 and 10 on March 28-31 and 8 on April 1-4.

F.K. Janda, OK1HH predicts quiet geomagnetic conditions on March 8-9, mostly quiet March 10-11, quiet to unsettled March 12, quiet to active March 13, quiet on March 14, quiet to unsettled March 15-17, quiet on March 18, mostly quiet March 19-20, active to disturbed March 21-22, quiet March 23-24, mostly quiet March 25, quiet March 26-27, quiet to active March 28-30, and quiet to unsettled March 31.

Have we mentioned recently that for HF propagation, we generally want higher sunspot numbers but low geomagnetic indices at the same time?

At you can see the latest NASA solar cycle prediction. They revised the forecast downward again. Last month they said that the cycle should peak this Fall with a smoothed sunspot number of 69. That was revised down by three points, and now they say it will peak at 66. These are International Sunspot Numbers, which have a lower scale than the Boulder numbers we use in this bulletin, which run about 35% higher.

Many readers wrote in concerning the news about a possible double-peak for the current solar cycle. There seemed to be a peak in activity around the end of 2011, then activity fell off last year. If true that the cycle peaks this Spring or Fall, we don't seem to be trending toward that activity yet.

Check for a video from NASA explaining this. Note you can watch the video in HD and full screen by selecting options at the bottom.

Thanks to John Campbell, K4NFE, Elwood Downey, WB0OEW, Gary Johnson, K5SWW, and David Dary, W5ZAX, for the tips on the story.

If you go to for the latest Preliminary Report and Forecast and turn to page 15, you can check the numbers for the latest prediction from Boulder. It shows a peak in September and October 2013, with levels about 27% higher than solar activity last month, February 2013.

See also that the peak in activity at the end of 2011 is represented by the higher numbers (smoothed, so the peak is not pronounced), then gradually declining. The averaging function seems to have moved that peak out to February and March of 2012. But the predicted peak this year is quite a bit higher than the previous peak. Let's hope that the second peak is indeed much more robust, as predicted.

At the forecast from last month shows higher values for the end of 2012 and the first few months of 2013. These reflect estimated future sunspot numbers, which would drag the average down. The numbers for each month are an average for a year's worth of data, six months forward, and six months back. The estimate for March 2013 went from 77 last month to 73 this month. The latest figure represents one more month of real recorded data than last month's prediction.

Note also on the next page that the solar flux prediction shows the peak for that parameter in August 2013.

Julio Medina, NP3CW of San Juan, Puerto Rico wrote, "Just to let you know that today 01 March 2013 from 1826-1837z I worked VU3WIJ and VU3WII on 20 meter SSB with 5x9 reports both way. I was using a vertical antenna at ten feet above the ground and 100 watts. Both stations had pile ups and they copied my signal very easily."

I replied, "On that day I would expect the band to just begin to open at that time, but signals should reach a peak from 2100-2300z."

Steve Hawkins, NG0G wrote: "On March 5 at 2213Z I had just worked TX5K (Clipperton Island) on 24 MHz CW. I live in Boone Iowa and it was getting on toward late afternoon." (See for the Clipperton DXpedition.)

"After working TX5K I stumbled across XT2TT (Burkina Faso) on the same band. Since by then it had been dark in Africa for hours I was very skeptical and thinking pirate. But I adopted the standard 'Work now, worry later' mode.

"I'll admit it took tweaking everything built into my FT-1000 MKV Field, and listening so hard there may have been arcing inside my skull, but I could hear them. I called and worked them about the 3rd call. At first I thought 'nooooooo, this must be a pirate,' as with my wimpy vertical, and the solar flux as low as it is, 24 MHz should not be open to Africa from Iowa at 2213Z. I was astounded when not only did they answer me, but I quickly showed up in their online log.

"I could almost hear (cue the Twilight Zone theme music.)

"Despite feeling like the guest on a certain late night talk show, I quickly launched into my best post-back surgery version of the 'Happy Dance.'

Talking later with a friend, K0KT, he reminded me that near to the equator, the MUF can be surprisingly high up to midnight."

Actually when running the numbers on W6ELprop, propagation over that path at that time on that band is not unusual. I entered 42.07 degrees North, 93.88 degrees West for Steve's location, and found the XT2TT DXpedition QTH at,

That page shows a grid square location of IK92fi, so I entered this into the AMSAT grid square conversion tool at

This yielded 12.3542 degrees North, 1.54167 degrees West for XT2TT. This turns out to be only 25 miles north of the default Burkina Faso coordinates in W6ELprop.

Based on these coordinates, the station is in the southwest portion of Ouagadougou, Burkina Faso's capitol city. I checked this at 4:17 AM Seattle time today, which is 12:17 PM in Burkina Faso and also 1217z. The temperature was 102 degrees F with humidity of only 11% in Ouagadougou. The annual rainfall there is only 35 inches, and the high temperatures between March and May reach 113 degrees F.

The path length is 5,767 miles (9,281 km), and on March 5 W6ELprop shows an opening beginning with a B rating (available 50-75% of the time) and signal-to-noise ratio of 40 dB at 1330z, changing to an A rating (opening 75-100% of the time) by 1430z. By 1830z the s/n ratio is 43 dB and it gradually increases to a peak of 48 dB at 2300z. Signals stay at that level, but availability degrades to a B rating at 2330-0000z, C rating (25-50% availability) at 0030z and D rating (1-25%) at 0100-0130z.

Sunset at XT2TT was 1812z on March 5, and at NG0G it was 0006z. So that path opens about 45 minutes after sunrise at NG0G (1248z), gets better after sunset at XT2TT, and finally begins fading around sunset at NG0G. A half hour after sunset in Iowa, that path is done.

For more info on using W6ELprop, see references at the bottom of this page, or check You can download W6ELprop at

Ken Miller, K6CTW of Rancho Cucamonga, California wrote, "I was up late last night working on the computer and saw that the Clipperton DXpedition was operating on 80 meter CW near the bottom end of the band. Just to satisfy my curiosity I turned on the 1960s station I've restored (Heathkit DX-60 with homebrew DDS-VFO and Drake 2-B receiver with 2-BQ Q-Multiplier feeding an inverted-vee dipole antenna) to see what I could hear. (Ken runs the old Novice power limit on this rig, just as he did on the same setup in 1967, 75 watts, or about 40-45 watts out.) Their signal here in Southern California was 20 over S-9 or better so I loaded up the DX-60 and gave a call after figuring out where the operator was listening (he was running JAs). Imagine my amazement when he came back to my call! I am always impressed that the operators at these DXpeditions can sort out a weak signal like mine out of the unbelievable racket. Thanks to them and also, what a surprise to see how good communications can be on the low bands late at night."

Ken wrote in a subsequent email: "I've restored this first DX-60 (and a Drake 2-B and 2-BQ Q-Multiplier) to get my feet wet. I am now in the process of rebuilding another DX-60 kit with all new parts. I re-plated the chassis and all the metal, and I've added an OA2 voltage regulator tube to the power segment of the 6CL6 oscillator section. That will prevent chirp on 10 meters.

"The VFO is a home brew DDS unit using the now 'retired' FCC-1 and FCC-2 from The NorCal QRP Club. For details, check the April or May issue of Electric Radio as Ray is publishing an article I wrote about my experience.

"I'm also home-brewing another improved version VFO using Jim, WA1FFL's DDS unit. This one is a significant upgrade to the unit described in the article."

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

Sunspot numbers for February 28 through March 6 were 63, 88, 90, 115, 103, 106, and 88, with a mean of 93.3. 10.7 cm flux was 105.5, 112.5, 111, 112, 114.3, 118.4, and 114.3, with a mean of 112.6. Estimated planetary A indices were 7, 27, 12, 7, 4, 4, and 3, with a mean of 9.1. Estimated mid-latitude A indices were 8, 23, 14, 6, 4, 3, and 4, with a mean of 8.9.

Source: W1AW Bulletin via the ARRL.

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