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Author Topic: 20 meter fading, and Es  (Read 7609 times)
N1AEP
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Posts: 2




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« on: July 24, 2016, 03:15:52 PM »

Lately, 20 meters sounds like 6 during an Es event. In other words, sometimes there are signals to be heard, and then suddenly there will be several. Certain ones will just drop out mid-qso ir mid transmission. A few stations will drift in very strong... then they drop out and often the band just gies dead again. Using a SWL rcvr, and these are afternoon and evening conditions  Assuming this is all F layer propagation, what would cause the rapid fading like that?

I am listening now. 45 min. ago i20 sounded dead -- only hear a couple of ssb signals and band sounded noisy. Now there are several ssb sigs and some are very strong. The band seems to be very shifty.

Also: At how LOW a frequency can Es occur? I have read that it can happen on 15; certainly 12, 10 and 6. Does the E layer or do sporadic clouds in the E layer affect 14 Mhz? 

Can D or E layer absorption be causing these daytime/evening rapid fading conditions?

73 et mny tks
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WD4ELG
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Posts: 991




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« Reply #1 on: July 24, 2016, 04:43:53 PM »

What time of day are you hearing this?  39 years in the hobby I have not observed Es on 20 meters, but I HAVE seen quickly changing conditions depending on time of day, sudden changes in solar activities, and even strong rain fronts (rare, but I did observe it on 30 meters).
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N3QE
Member

Posts: 3767




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« Reply #2 on: July 25, 2016, 07:34:49 AM »

Can D or E layer absorption be causing these daytime/evening rapid fading conditions?

There were some solar flares over the weekend, that were known to cause blackout-type activities that would sound like rapid fading. Do these line up with your observations? See quote from solarham.com below:

Quote from: solarham.com
Region 2567 is going out with a bang. Three moderately strong solar flares were observed early Saturday morning around the departing region. The first was an M5.0 at 02:11 UTC (July 23). The second event, a strong M7.6 at 05:16 UTC, was quickly followed up by an impressive M5.5 event at 05:31 UTC. The third event (M5.5) was associated with a 10cm Radio Burst, Type II and IV radio emissions, and a coronal mass ejection (CME) that appears to be directed away from our planet. Other than the brief radio blackouts at the time of the flaring, no major impacts to our planet is to be expected. Stay tuned to SolarHam.com for the latest information.
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ONAIR
Member

Posts: 2660




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« Reply #3 on: July 25, 2016, 09:37:35 AM »

Lately, 20 meters sounds like 6 during an Es event. In other words, sometimes there are signals to be heard, and then suddenly there will be several. Certain ones will just drop out mid-qso ir mid transmission. A few stations will drift in very strong... then they drop out and often the band just gies dead again. Using a SWL rcvr, and these are afternoon and evening conditions  Assuming this is all F layer propagation, what would cause the rapid fading like that?

I am listening now. 45 min. ago i20 sounded dead -- only hear a couple of ssb signals and band sounded noisy. Now there are several ssb sigs and some are very strong. The band seems to be very shifty.

Also: At how LOW a frequency can Es occur? I have read that it can happen on 15; certainly 12, 10 and 6. Does the E layer or do sporadic clouds in the E layer affect 14 Mhz? 

Can D or E layer absorption be causing these daytime/evening rapid fading conditions?

73 et mny tks
    10 meters has been crazy lately as well!  The band can be quiet one minute, and then suddenly come to life.  Signals could fade from S-9 to zero during the time it takes an op to speak one sentence!
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KB8GAE
Member

Posts: 143




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« Reply #4 on: July 25, 2016, 01:22:21 PM »

Here is a link to a presentation on 20/15/10 Es during WRTC 2010

www.arrl.org/files/file/Antenna%20Book%20Supplemental%20Files/22nd%20Edition/PVRC_NCCC%20HF%20Propagation%20and%20Sporadic%20E.pdf

Rich KB8GAE
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WD4ELG
Member

Posts: 991




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« Reply #5 on: July 25, 2016, 07:55:38 PM »

Rich, that is fascinating!  Thanks for sharing!
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