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Author Topic: High SFI  (Read 1580 times)
SWMAN
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« on: July 09, 2012, 07:01:43 AM »

 I was just real curious again about something. If the Solar Flux Index is so high recently such as 178 today, why are the bands so dead. 10, 15 and 20 are almost silent here in Dallas Texas. I hear a few stations at times but nothing real loud or very many. With a SFI that high you would think there would be lots more activity.
  Thanks again and 73    Jim  W5JJG
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W0BTU
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« Reply #1 on: July 09, 2012, 07:44:51 AM »

10 (and CB!) was open yesterday. I worked several stations on 10. It's just that hardly any hams seemed to know about it. The CB'ers knew, I'll say that!

Having said that, I was kind of wondering the same thing. For as high as the SF was (over 180), I would have thought signals would have been stronger. One site indicated that the opening was sporadic-E.
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N3QE
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« Reply #2 on: July 09, 2012, 07:48:20 AM »

Best place for activity over this past weekend, was early evening on 20M. DLDX RTTY contest was a moderately successful activity for me. But... 15M didn't have much going on, and 10M very very little (I heard no DX there and tried calling for a while too.).

Geomagnetic storms make a lot of DX "skip" paths at high latitudes and shorter wavelengths quite difficult.

Maybe more importantly, it's the middle of summer, and there just plain isn't a lot of activity. Some folks specialize to Sporadic E DX on 6M during the height of the summer.

Next big thing is the IARU contest.
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KG6YV
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« Reply #3 on: July 09, 2012, 01:17:32 PM »

In the summer months the D-layer absorbs signals above 10 mhz.  The higher the flux the more D-layer absorbtion during daylight peaking at noon local time.  20M will be open well after dark as the d-layer deionizes.  15 and 10M may be open for a few hours around dawn and dusk too.

Greg
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KE3WD
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« Reply #4 on: July 09, 2012, 02:10:28 PM »

10 (and CB!) was open yesterday. I worked several stations on 10. It's just that hardly any hams seemed to know about it. The CB'ers knew, I'll say that!

Keeping any kind of cheap CB in the shack, even a walkie-talkie with its built in rubber duckie or whip, is indeed a good way to keep track of when 10 might be happening.  Turn the Squelch down on the CB, set it to channel 6 and fahgeddaboudit, if the skip is happening, guaranteed they'll be breakin' the squelch and typically way before the hams figure out that 10 is open.  Likely because the majority of them have but one band to work. 


73

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W0BTU
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« Reply #5 on: July 09, 2012, 03:11:43 PM »

Keeping any kind of cheap CB in the shack, even a walkie-talkie with its built in rubber duckie or whip, is indeed a good way to keep track of when 10 might be happening.

Yup! Or better yet, program a CB channel or two into our ham receivers. And many receivers and transceivers have squelch, too.

There are also a number of low-power CW beacons below 28.300. I hear them all the time during the day.

I also look at the MUF at http://www.hamqsl.com/solar.html from time to time. That's the main reason I have one of their banners at the bottom of my web site's main page. Can anyone explain the different changing colors in that MUF bar graph? Never mind, I found them at http://www.hamqsl.com/solar2.html#usingdata.

One problem with 10 and 12 is that most people listen, hear nothing, and switch bands without first sending a few CQs. But if we hear an amateur beacon, or activity on CB, chances are we can make a contact on 10.
« Last Edit: July 09, 2012, 03:46:26 PM by W0BTU » Logged

W0BTU
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« Reply #6 on: July 09, 2012, 03:19:15 PM »

In the summer months the D-layer absorbs signals above 10 mhz.  

I thought it was below 10 MHz. But it's been so long since I studied anything about propagation, I can't say for certain.

Anyway, historically 10 meters has been a daylight band, and the higher the SF, the better 10 and 12 usually are. In years past, the SF has been so high 10 meters was usable 24/7. But I'm still puzzled as to why 10 wasn't in much better shape with the SF so high and the K-index so low.
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KC9TNH
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« Reply #7 on: July 10, 2012, 04:43:37 PM »

AE4RV sagely told me once, "Electrons are lazy." (ergo, path of least resistance)

I have decided also that in the summer they are very proud, and will not return to Earth after suffering the indignity of having been 'absorbed'.

Up in my neck of the woods lots of other factors play too. When the Aurora dips south it seems to squash signals as well. Makes the nicely gelled heavens in cooler winter time look pretty good....
 Grin
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73
Wes -KC9TNH
"Don't get treed by a chihuahua." - Pete
G8YMW
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« Reply #8 on: July 10, 2012, 05:11:43 PM »

The D layer starts absorbing at around 1400 KHz going up in frequency as solar activity increases. Which is why 80 metres shuts down during aurorae. How far up this effect goes I'm not sure.
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W0BTU
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« Reply #9 on: July 10, 2012, 07:35:37 PM »

Up in my neck of the woods lots of other factors play too. When the Aurora dips south it seems to squash signals as well.

Yes, unless you're on VHF. When I lived in Toledo, Ohio I used to love the aurora openings on 144 MHz that made DX possible.
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