Been off of the air for awhile - curious about how the solar cycle is...

Discussion in 'The DX Zone' started by WB9LUR, Dec 19, 2017.

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  1. NM7G

    NM7G Ham Member QRZ Page

    This time of year 1730-1900Z works for Europe here, 150 miles to your south. F, EA, DL, PA, I, LZ. SP, and EA8 were available today. Also heard the CS3B beacon. The loudest French sig was peaking S7. Have fun.
     
  2. WE4E

    WE4E Ham Member QRZ Page

    There's activity lots of places if you're inclined to find it. I hear Europe just about every night on 40m, and work it frequently. 10m was open last night until maybe 0600z. My radio time tends to be late in the evening so I can't comment on the rest of the day.

    Here's the thing: the bands are always dead if no one transmits. If we all just tune around and listen for activity there likely won't be any, opening or not.
     
  3. K4HX

    K4HX Ham Member QRZ Page

    I've looged over 350 DX contacts since 23 Nov 17. Most of these have been on 40 meters and the rest on 80 and 20 meters. The Pacific is coming through almost every afternoon on the 40 meter long path with many JA, HL, YB and VKs worked. The higher frequency HF bands may be poor (although 20 meters OK much of time), the lower frequency bands are certainly FB.
     
  4. GM4BRB

    GM4BRB Ham Member QRZ Page

    Old post to reply to but not worth a new 'thread'.
    This is how the bands look this evening. SV's working SV's. No-one in Europe working anything beyond the Canaries: EA8. This Norwegian LA7 has had the fortune to work himself, as the DX!
    ScreenShot3096.jpg
    And you'll have noticed perhaps, especially in poor solar-cycle condx, and during times of lower atmospheric pressure of the winter, the lower to mid short-waves in particular suffer a steep tail-off in performance. I listen daily to VOLMET air-force weather forecasts around 5.5Mhz (D-layer reflections) which peak to +20db over S9 in Summer but I see the signals completely vanish as both solar ionization diminishes overall, and I suspect altitude of or even the very presence of the D-Layer is in question, as the cold-weather (lower-atmos-pressure) arrives.
     
    Last edited: Jan 18, 2018 at 7:05 PM
  5. GM4BRB

    GM4BRB Ham Member QRZ Page

    According to my old but precious "Sun, earth & Radio" book, Ionisation of the especially lower D Layer is entirely dependant upon COSMIC radiation, not Solar radiation.

    This COSMIC radiation consists of VERY rapidly moving charged particles, and ionisation is greater at greater depths (lower altitudes) where the occurence of air molecules for them to interact with is the greater. The peak balance between free ionic electrons is at a 'balance point' where the rates of production and absorption is at an optimum, this height being about 60-70Km.

    Interestingly, observations reported in this book show that D-layer ionisation in the lower region (as described above) reaches a peak at a period coincidental with SOLAR MINIMUM, whereas at 70 to 80Km the layer behaves in phase normal with the Solar-cycle, since at this altitude the Sun, Earth &  Radio.jpg electrons are ionised by Solar and X-radiations.

    The book goes some way to affirming my hypothesis that, pressure and altitude may have a seasonal effect on D-layer propagation:

    "Measurements of temperature & pressure made at heights of ~30Km have shown that sometimes in regions extending over a few thousand kilometres, there is a sudden heating of the air, a so-called 'Stratospheric Warming", and evidence is increasing that warmings of this kind are associated with increases of absorption ...
    If this is established with certainty, it will be the first clear evidence that changes in the lower atmosphere and the ionosphere can sometimes have a common cause."

    PP's 153-157. "Sun, Earth & Radio" J.A Ratcliffe. 1970
    (It's a valuable book, with unfortunately a terrible binding to it, such that every original copy needed repetitive repair to survive any real use).
    The book has a unique specialist approach to appreciating the ionosphere that is not touched on in our amateur textbooks, at all, and which I think calls for an updated version to be thought about.
     
    Last edited: Jan 18, 2018 at 9:30 PM

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