Author Topic: Propagation  (Read 488 times)


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« on: April 28, 2012, 0121 UTC »
SB PROP @ ARL $ARLP017 ARLP017 Propagation de K7RA

ZCZC AP17 QST de W1AW Propagation Forecast Bulletin 17 ARLP017 From Tad Cook, K7RA Seattle, WA April 27, 2012 To all radio amateurs

SB PROP ARL ARLP017 ARLP017 Propagation de K7RA

Solar activity revived over the past week, with a big increase in sunspot numbers. On Friday, April 20, the daily sunspot number reached 162, and four days later on April 24 the number reached 169. This level of activity was not seen since last fall, when the daily sunspot number reached 173 on September 16, 184 on October 21, and 208 on November 9.

Average daily sunspot numbers more than doubled over the previous week's average, rising 73 points to 144.7. Average daily solar flux was 133.9, an increase of nearly 29 points.

Associated with all this was a rise in geomagnetic activity, peaking with a planetary A index of 35 on Tuesday, April 24. The geomagnetic activity increase was due to several solar flares launched from new sunspots.

The latest forecast shows solar flux of 115 on April 27, 110 on April 28, 105 on April 29-30, 100 on May 1-2, 95 on May 3, 105 on May 4, 110 on May 5-6, 115 on May 7-8, 120 on May 9, 130 on May 10-12, 135 on May 13, 140 on May 14-17, 135 on May 18-21, followed by 130, 125, 120, 115 and 110 on May 22-26 and 105 on May 27-31.

Predictions for planetary A index are 10 on April 27, 5 on April 28 through May 1, 8 on May 2, 5 on May 3-7, 8, 12, 15 and 10 on May 8-11, 5 on May 12-19, 12 and 10 on May 20-21, and 5 on May 27-31.

Jim White, WD0E, worked FK8CP (New Caledonia) at 0027z on April 26. He wrote:

"Just worked FK8CP on 6 meter SSB from DM79, about 35 miles SE of Denver, at 0027z on April 26. Amazing 7,131 mile path. For an hour before I worked him, on DX Sherlock (see there were spots of him from Southern California but not much in the way of sporadic E between here and SoCal. This must have been an Es cloud just off the coast of SoCal linked to TE. He was in and out of the noise but we heard him for about 20 minutes off and on. I'm using a 5 element Yagi at 40 feet with a low NF mast mounted preamp and 9913 cable. I had lots of noise reduction cranked into my IC756Pro. A THP amp gives me 650W, with about 550W to the antenna."

I think when Jim writes "low NF mast mounted preamp", NF refers to "noise floor."

Later at 0215z on Friday, April 27 (Thursday night in North America) Jim commented, "Looking at it again I think the E cloud was right over southern California, not off the coast. For the geometry to work it had to have been there, I think. A bunch of Hawaii into the West Coast right now with E clouds over Mexico and Kansas. We are listening and hoping we get that double link into Hawaii tonight!"

Jeff Hartley, N8II of Shepherdstown, West Virginia sent in an interesting report.

"Interesting to note that 10 meters is far from dead and prop seems to pick up out west around sunset on 10 and 12 meters. The SFI today Sunday, April 22 has spiked up to 142. Yesterday, April 21, 10 meters sounded very similar to several days before in the 2300Z hour when the flux was lower. There have been some very loud signals from South America up until about 0020Z most days, sunset was around 2350Z. Also heard were loud W6's in southern CA and a few VK's and ZL's. Worked YJ0VK on 12 meters with a weak signal."

"Saturday evening April 21, 12 meters opened to NL7G and FO5WBB along with the 10 meter propagation mentioned above. Conditions to JA were excellent on 15 meters around sunset (2400Z) with many loud JA's as loud as S9 (above normal for us near DC). TO3X was loud running a 15 meter phone pile-up from St Barts at 0015Z. There were also JA's on 17 meters as well as Zone 19 Asiatic Russians. 20 meters was not open well to JA at the same time, but RK9LWA/9 had a S7 signal from a rare RDA (refers to the Russian Districts Award)."

"30 meters has been in excellent shape to Europe around our sunset with HA9RT S9 plus 20 db on my dipole just after 2400Z on April 21 and MI0GRG S9 plus 10 db running a big pile up at 0004Z."

"Monday April 23 was very unusual with disturbed conditions in the morning and most of the DX action on 15 meters. I started off at 1357Z getting YB4GU in response to my CQ, S8 on Sumatra, who was running 100 watts and a dipole and very fluttery. My next QSO was the opposite end of Indonesia YC9BEC on Bali with very little flutter. Signals from all over EU were fluttery and peaking north to about 20 degrees. Even A61ZX and 5B8AD on Cyprus were peaking around 20 degrees. I never recall such an extreme skew to the north on signals so far south, normal headings are 45-50 deg. Conditions continued about the same for an hour working on CW, RU9HM, RU4SO, UA3EDP/6, RU1QD, and RT3I, all peaking north. At 1543Z 5Q4B in Denmark on 15 SSB was best due north fading over 10 db down to about S2 during our QSO."

Note that Jeff made a comment about disturbed conditions on April 23. Checking we see that April 23-25 had high A index readings at all latitudes. Interesting comparing April 24-25, where we see mid-latitude and planetary A index decrease and high latitude values increase over the two days.

Ever wonder what is going on in Sunspot, New Mexico? Check out this article from CNET:

Rich Zwerko, K1HTV of Amissville, Virginia sent a response to K9LA's advice in last week's bulletin to get on the air. Rich wrote:

"Well, today (April 21), a day before my 70th birthday, I followed your advice. After breakfast I went down to the K1HTV shack, got on 20 meter RTTY with 80 Watts and worked YJ0VK for digital country #275. Later in the morning, around 1530Z with my barefoot K3 and with the A3S tri-bander, I started to hunt for some DX on 15 meters. A number of 4X/4Z stations in Israel were worked in the Holyland contest. Swinging the beam north, HS0AC on 15 meter CW was quickly added to the K1HTV log. This was followed by 2 more stations in Thailand and 2 in Indonesia, all on SSB. 15 meter RTTY produced QSOs with EY7AD, SU9VB and VU2NKS. Brad, FO8WBB (formerly FO/N6JA) was worked on 12 meter CW at 17:19Z. HF conditions were so good that I worked all 6 continents in less than 45 minutes!"

"On 10 meters D2QV had a nice CW signal from Angola. A number of European stations also were worked with the beam east. Around 17:55Z I heard 9M2IDJ on 28.447 on SSB via this same skewed path over Africa. Last November I worked Masa on 10 meter CW during an afternoon opening on this same skewed path for #331 on 10 meter CW with 100 Watts. My last 15 meter SSB over-the-pole QSO today was with YB1ALL at 18:30Z. Gus reported that it was 1:30 AM local Indonesian time. Not bad for 15 meter propagation."

"Last Sunday (April 15) produced 50 MHz QSOs via an Es-to-TEP opening from the K1HTV Virginia QTH to the Caribbean and South America. I heard 14 stations (3 were beacons) in CX, LU, PY, KP4 and HI8 and worked 7 of them with 100 Watts. But I got on the air 15 minutes too late, missing CP6UA in Bolivia, the last country I need on continental SA. Bernie, W3UR and Dave, N3DB were on the ball and worked the CP. As they say, you snooze, you lose. Hope that there is a next time and another path to Bolivia before old sol goes to sleep and solar cycle 24 is history."

Check out Rich's bio and photos at You'll have to log in, but registration is free.

Scott Bidstrup, TI3/W7RI sent this article on the sun's magnetic polarity

Jon Pollock, K0ZN of De Soto, Kansas had this to share.

"Wow! This is like the good old days in cycle peak in the mid '80's! Higher bands open til nearly midnight."

I was on 17 meter CW about 10:00 to 11:30 pm CST Saturday night (April 21). Operations started with a QSO and ragchew with K7URU in Spokane, WA. Sigs were very good for about 35 plus minutes and we had a nice chat. Signals started building up to well over S-9, clear indications the Gray Line was approaching, and then bingo! The band crashed and signals faded to nothing. Within about 1 to 2 minutes the band was dead, no signals. Then about 5 minutes later, several very strong signals suddenly show up and the band had many signals. One was a pile-up of European stations and the other was an EA8 running about 10 db over S-9! The Europeans and the Spanish station lasted about 10 to 15 minutes, then totally disappeared, and the western Pacific came in strong. I ended up working an FK8 (New Caledonia near Australia), a ZL and then Argentina. All of them had strong signals. The ZL was running way over S-9."

"This is the crazy, fun stuff at the top of a sunspot cycle, with all kinds of DX on the upper bands at night. The funny thing about 17 meters was that there were no phone stations at all; all the activity on 17 meters was CW in the lower end of the band. Classic conditions. The band had a very low noise floor and was very quiet and very long skip. I could not hear ANY state side stations. Cool when it happens, but the sudden, short, appearance of the European stations at about 11 PM CST was some really 'kinky' propagation. Wonder what kind of prop that was and whether it was Long Path or short path? I kind of suspect it may have been long path or ionospheric ducting."

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For more information concerning radio propagation, see the ARRL Technical Information Service 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

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Sunspot numbers for April 19 through 25 were 122, 162, 147, 118, 158, 169, and 137, with a mean of 144.7. 10.7 cm flux was 137.8, 141.7, 149.1, 147.9, 141.8, 133.6 and 127.2, with a mean of 133.9. Estimated planetary A indices were 5, 7, 6, 7, 23, 35, and 21, with a mean of 14.9. Estimated mid-latitude A indices were 5, 7, 6, 7, 21, 30, and 18, with a mean of 13.4. NNNN /EX