Solar Eclipse and effect on AM propagation

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This topic contains 18 replies, has 11 voices, and was last updated by  Andy Brown 2 years, 2 months ago.

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  • #31288

    lastday
    Participant

    Does a solar eclipse affect AM radio? Presumably AM stations will be at their full daytime power here on 8/21. Will they suddenly be carrying much farther for a few minutes? Or will there be no effect.

    Enquiring minds want to know. 😉

    #31289

    jr_tech
    Participant

    Likely… Ham activity is planned:

    http://www.hamsci.org/basic-project/2017-total-solar-eclipse

    Sky and Telescope suggests AM radio observation:

    “Observe” August’s Eclipse with Your AM Radio


    could be interesting.

    #31290

    lastday
    Participant

    Thanks jt. Good info.

    #31295

    Broadway
    Participant

    I viewed the 1979 eclipse from my living room window…of course that one was also just 2 minutes…quite the show just watching the outside…this time from the same house and street, I am going outside with earbuds connected to my AM digital radio and cell phone camera on…be flipping channels and probably enjoying seeing neighbors comments-reactions…2 minutes goes fast…

    #31311

    Alfredo_T
    Participant

    One of the experiments that I plan was to monitor the AM class C frequencies. This will require nulling out local stations (I described the conflicts for each frequency in a different thread). It is possible that this experiment won’t yield useful results because we are too close to the path of the eclipse.

    The second experiment will be to listen to stations from other cities that will experience the eclipse. Stations from Boise or Idaho Falls might be a good bet.

    #31315

    semoochie
    Participant

    I’ve mentioned this before but the ’79 eclipse garnered nighttime conditions and all the distant stations returned. With all the ambient noise these days, I doubt if we’ll hear much this time.

    #31319

    Steve Naganuma
    Participant
    #31327

    Alfredo_T
    Participant

    I reached the end of the Sky and Telescope story after I wrote my previous post. I then noted the interesting observation that reception becomes strongest when the eclipse is closer to the transmitter, rather than halfway in between the transmitter and the listener.

    Casual radio listeners in residential settings won’t be able to appreciate how the reception is changing. The only way to go on this is with an outdoor antenna. I have noticed that large parking lots that are away from overhead utility lines can be surprisingly quiet. One just has to be careful about potential intermodulation issues from multiple strong signals (don’t go to Clackamas).

    #31331

    dialtwirler
    Participant

    This report on the 1999 UK total solar eclipse gives some idea of what to expect here:

    https://arxiv.org/ftp/arxiv/papers/1703/1703.01491.pdf

    #31389

    Scott Young
    Participant

    1310 KNPT in Newport just faded up out of the noise in NE Portland a few minutes ago. Right on schedule!

    #31390

    jr_tech
    Participant

    Right now I am hearing KSL Salt Lake 1160 and KOA Denver 850 just as well as night time.

    #31391

    Alfredo_T
    Participant

    The skywave stations have almost all faded out by now. While they were receivable, I managed to record many 30 second snippets. I was able to ID a few of them.

    What I observed was a bit different than what I expected. On the class C frequencies, a few stations came up simultaneously, but they were quite weak. I heard stations from the north (1470 KELA Centralia and 1680 KNTS Seattle were both pretty strong). 1440 KODL was fairly strong when, even though I had the antenna pointed the wrong way at the time.

    I did hear a weak KSL (perhaps, I tuned in too late). I didn’t try for 850 because I expected that KPAM would clobber anything on that frequency.

    In general, the stations above 1300 kHz benefited the most from the eclipse propagation conditions.

    #31392

    jr_tech
    Participant

    I expected that KBPS 1450 would get clobbered like it does at night, but it remained fairly listenable during the whole time. WWV on 5 mHz came in pretty well and I think that I faintly heard it briefly on 2.5 mHz, as well.
    For a time, there were 9 or 10 neighbors in the driveway peering through the filter-equipped C-5 Celestron. Several nice groups of sunspots added to the interest.

    #31393

    Alfredo_T
    Participant

    I briefly projected an image of the sun onto a piece of paper using one side of a pair of binoculars. Doing this, I found that the sun had started to be covered up much earlier than I anticipated (around 9:45 AM).

    Edit ADD: The next total solar eclipse will be July 2, 2019. To see it, one would have to travel to Chile.

    #31396

    Randy_in_Eugene
    Participant

    I didn’t have a chance to check until just after local totality (99% at my location). Heard 670 and barely 1140 from Boise, 930 out of Yakima, 870 from Tri-Cities, 1000, 1090, 1150, 1560, 1680 from the Seattle area, 1380 Everett. Didn’t hear KIRO AM, KSL, and the local 840 made 850 unlistenable.

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