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When did hams start paying attention to gray-line propagation effects?

Discussion in 'Ham Radio Discussions' started by W7UUU, Apr 16, 2018.

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  1. KD2NOM

    KD2NOM XML Subscriber QRZ Page


    I heard about gray-line a couple of months ago in a different thread and noticed that every morning as the gray-line crossed the east coast of the US, Australia lit up for me. Day after day and week after week I noticed it and started leaving PSK Reporter up full screen on a separate monitor.

    40 meter seems to be the best for me but it was something I learned about thru experience before I learned about it via research.
    W7UUU likes this.
  2. KB2FCV

    KB2FCV Ham Member QRZ Page

    Hi Mark, yup 40 in the mornings there is usually a nice pipeline to VK, ZL, etc! JA's come in a well that time of day. Early evenings are great for Europe, Africa and the Middle East.
    WZ7U likes this.
  3. WC5P

    WC5P Premium Subscriber QRZ Page

    I still have a DX Edge. That may be the slide rule device that UUU mentioned.
  4. KS2G

    KS2G Subscriber QRZ Page

    The DX Edge® was a plastic slide-rule day/night/gray-line tool developed by Tony Japha, N2UN(sk), who registered the name as a trademark and sold the device through a company called Xantek, Inc.

    It consisted of a rectangular map of the world, with shaded clear-plastic overlays showing the day/night/gray-line pattern for each month of the year. By positioning the overlay on the map based on the time-of-day at the desired location, you could see which parts of the world were in daylight and which were in darkness and where the gray-line fell at that particular time. Sliding the overlay across the time scale demonstrated the movement of day/night and the gray-line.

    W7UUU and WZ7U like this.
  5. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    The term "gray line" is relatively new. However, even back in the late 1950s, when I got my license, the "olde tymers" told of working DX, along what is now called the "gray line", back in the 1930s.

    This method of working DX has been known for many decades. It is just the "term" hasn't been around that long.

    Glen, K9STH
    VK2WP and W7UUU like this.
  6. N5AL

    N5AL Ham Member QRZ Page

    I have often thought what would be cool is a project that mounted a spare, underutilized flat screen TV to the shack wall and connected it to a cheap Raspberry Pi computer, running software to emulate a Geochron mechanical clock. You wouldn't even have to set the set the time nor the date, as the Raspberry Pi would be connected over WiFi/Internet to a network time service.

    Edit: After typing this, I went to the Geochron website and I see they are now selling such a product, albeit with more functionality and a higher definition, 4K UHD display capability.
    Last edited: Apr 16, 2018
  7. W4NNF

    W4NNF XML Subscriber QRZ Page

    Geochron clocks are beautiful. Expensive, but beautiful.

    I see they are now offering a more reasonably priced alternative, too, a widget that plugs into your TV with firmware that does their clock onscreen. For most of us a nice computer program is probably more practical if you don't want to pay for a real Geochron.

    Would I love to have a mechanical Geochron? Heck yeah...but...the 2K + one requires would get me a good part of the way to a new IC-7610, and that's always been the problem. ;)
  8. WZ7U

    WZ7U Ham Member QRZ Page

    I heard about gray line before I had my ticket and have been chasing it ever since, with varying degrees of success.

    The DX Edge is amazing in it's simplicity. I bet they're not cheap too, collectors items and all that.
    W7UUU likes this.
  9. VK2WP

    VK2WP XML Subscriber QRZ Page

    Not quite the answer Dave UUU was after, this pre war radio times calculator, the centre wheel rotates and gives the times pm and am when the transmitting country can be recieved in your home country.

    The centre wheel will give an indication of a grey line although I think in those days the grey was not known as such. Remember seeing the grey line globes shown by W6RZ as youngster in the 1950's/60's.

    IMG_4609_1.JPG IMG_4610_1.JPG
    KA0HCP, WZ7U and NL7W like this.
  10. W7UUU

    W7UUU Super Moderator Lifetime Member 133 Administrator Volunteer Moderator Platinum Subscriber Life Member QRZ Page

    Wow!!! What a beautiful device indeed!!

    N7ANN likes this.

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