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Cat on a hot tin roof

Discussion in 'CB Antennas' started by kopcicle, Feb 1, 2020.

  1. kopcicle

    kopcicle Sr. Member

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    Or something like that

    This is going to be another one of those long tales, so you've been warned.

    So in the foothills of the Cascade Mountain Range, Northwestern corridor United States of America, Evergreen State, Northern hemisphere of the planet Earth, out there on one of the many spiral arms of the Milky Way galaxy...

    I once went into a bit of detail about living in the woods, away from all the other living things in the woods, solitary, hermit like, attempting to avoid the next upright walking impersonation of a human being that right and truly deserved to be strangled and deposited down a mine shaft. Well here is a little bit more detail.



    When you have a channel selector or VFO accompanied by an off on switch it's relatively easy to have contact with the outside world. If you've had it with the misfits, morons, maladjusted and misaligned zombies of the airwaves all you have to do is change frequency or turn it off. This is a much safer and socially acceptable method of human contact than allowing some brainless idiot to exceed my patience to the point where I gouge out their eyes, rip off their head, and stomp what's left into a bloody puddle.

    On to the meat of this monologue. When you are limited to a bit less than 35 amps total line current, when available, and somewhat less during the winter months you have to make do.
    There were several "generators" , wind, solar, hydro, and peltier. (look it up. Peltier work in reverse). Any of these generators have their downside, from lack of fuel, sun, wind, water, to noise from the Onan or 12 volt mini generator. The only up side was KW/Hrs.

    This situation was the opposite of most that we encounter. Being somewhat in a hole but far enough from man made noise the "you can't work them if you can't hear them" was more like "I can't work them because no one can hear me".

    The A.R.R.L. Antenna Handbook. If you don't have one, can't find one, can't afford one, ask nicely and we'll see what can be done.

    If you can't apply brute force then outsmart the bastiches!
    I set about a phased array made up of vertical elements, spaced horizontally to provide maximum broadside gain. I started with two elements and kept going as time and materials allowed. I ended up with 18 elements. The amount of broadside gain is an exercise left for the reader.

    When I was able to waste KW/Hr's I had a few 2SC2879's around or this "thing" that was 2X 6KV6A > 4X 6MJ6 as well as a collection of antique Johnson, Gonset, Heath, and other homebrew I could apply to the already significant gain of the broadside array. This created a noticeable disturbance in the force.

    It was fortunate that those that took the time to hunt my signal down turned out to be for the most part to be humble, humorous, thoughtful and polite human beings, mostly. I did have occasion to greet one idiot attempting to vandalize not just my antennas but vehicles on my property. This brain dead boojum was given no option but to be stripped naked and duct tapped to the utility pole at the end of my driveway. I called the Sheriff and comedy ensued. I don't know how the story leaked out but the "legend" began there and any additional momentum it gained was purely by design :)

    Okay back to the Radio Frequency portion of this monologue. In addition to the gain array I had an omni on a tin roof. I'd read that as the diameter of the 1/4 wave radiator increased it's resonant length decreased. Having a surplus of wood stove chimney sections I set to work.

    Construction was easy enough but I needed an insulator. My sister comes up with a glazed terracotta bottom for a flower pot. I used the hole in the middle to fix a disc of plastic the inside diameter of the stove pipe to locate it. I screwed a bit of wood to either side of the roof peak to give the ceramic level mounting and placed it downside up in the middle of a 20' X 36' tin roof.

    Tuning with tin snips, a noise bridge, a VSWR meter, and more patience than I had used in building an antenna in several decades. A 1/4 wave isn't just shorter in 6" pipe, it's much shorter. Add to this that it had to have a "hat" to keep the water out the "capacitive hat" effect shortened it further. Imagine having to disconnect the guys and sit on the roof for every adjustment and re erect this floppy mess multiple times.

    In the end it was worth it. Broad banded doesn't go nearly far enough to describe it. As for it's power handling, all I can say is I loaded down my modified Miller AEAD-200LE to near stalling while driving a ceramic tube and was not able to compromise the antenna.

    There were several particularities. Look up "St Elmo's Fire" if you don't already know. Under the proper conditions the effect was spectacular.
    The edges of the roof were at an extremely high RF voltage potential just off resonance. A bird on the edge off the roof never knew what hit him. I didn't know a raccoon could make that noise. I did have to check the roof before transmitting to make sure it was clear of cats.

    So in case anyone was wondering , large diameter 1/4 wave radiators on a tin roof work. Just don't expect them to follow any formula, natural or unnatural law, design rule or previous intellectual discourse. In other words , you're on your own.
     
    #1 kopcicle, Feb 1, 2020
    Last edited: Feb 2, 2020
    Crawdad, xm49north7, WECSOG and 8 others like this.

  2. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    Firstly - some research is needed to understand such phenomenon...

    If taken literally by todays younger generation, they might mis-interpret St. Elmo with another type of Elmo that responds more to tickling than Heartburn...

    ElmoHeartburn.PNG
    TumsAnyone.jpg

    Perhaps a better approach is to be reserved for a search under WIKI

    Envisioning St. Elmo's Fire
    StElmosFire.jpg

    Just wanted to clarify...
     
    #2 Handy Andy, Feb 2, 2020
    Last edited: Feb 2, 2020
  3. Captain Kilowatt

    Captain Kilowatt Professional Amateur
    Staff Member

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    giphy.gif
     
    Redbeard U812, Tallman and kopcicle like this.
  4. loosecannon

    loosecannon Sr. Member

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    loved that story.

    was the broadside array affixed to trees near the ground or was it up in the air?

    that stovepipe had one hell of a K factor!
    LC
     
    Redbeard U812 likes this.
  5. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    Me and Elmo been drinking the same thing, Jack Daniels Tennessee Fire. Why can’t I blow out cool flames like that? I’ve heard of putting fire in the wire but that’s just ridiculous, Elmo.
     
    Redbeard U812 likes this.
  6. Handy Andy

    Handy Andy Do Your Research First, Then Decide...

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    It shocked me too (SIC - Groan)

    I never knew Elmo was a saint - gotta' use better batteries...
    • Just because of the search engine turned this up even before St. Elmo's Fire - The Movie...I didn't want to shock the kids, or the too young at heart - over a rather graphic image of a Fire-Breathing Elmo...
    I personally think it was hilarious but then, I did want to put up a notice about what your search engine might provide you in return(y)(y)

    Good to see you out here...
     
    Redbeard U812 likes this.
  7. Road Squawker

    Road Squawker Sr. Member

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    Cat_on_a_Hot_Tin_Roof,_Jerusalem.jpg ,,,
     
    Marconi likes this.
  8. TheRealPorkchop

    TheRealPorkchop Certified Sith Pimp

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    Yeah I’m just hanging with Elmo tonight, kinda worried though cause he wanted to invite Burt and Ernie.
     
    Redbeard U812 likes this.
  9. AudioShockwav

    AudioShockwav Extraterrestrial Admin
    Staff Member

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    Lol
    I want to see the Video........

    73
    Jeff
     
  10. Slowmover

    Slowmover Elmer

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    I want the raccoon recording. They’re just so innocent as you amble past . . . openly plotting destruction in raccoon-ese of something that important to you.

    Capture one in a Havahart. Distress the others by allowing hours to pass . Remove said Havahart with prisoner to garage and loudly play that recording.

    .
     
    Shadetree Mechanic likes this.
  11. Slowmover

    Slowmover Elmer

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    And I want the .gif of kopcicle driving that welder
    harder, and Harder, and HARDER

    “. . old Charlie stole the handle
    and the train she won’t stop rolling,
    No way to slow down”

    .
     
    Crawdad and Shadetree Mechanic like this.
  12. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    What if the reaction of the distress causes them to come to help? You could end up with a yard full. Haha
     
    Slowmover likes this.
  13. Shadetree Mechanic

    Shadetree Mechanic 808 On The North Side of Dover

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    I can't stop thinking about the stove pipe. What was going on inside when you hit the key? I assume the RF was radiated inside of it too? Could you cook food in it? What would having a ground rod running up the center of the inside do? I am going to have to try it now.
     
    Crawdad likes this.
  14. Crawdad

    Crawdad Well-Known Member

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    You just have to like anyone that can quote Ian Anderson
     
    Shadetree Mechanic and Slowmover like this.
  15. kopcicle

    kopcicle Sr. Member

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    He hears the silence howling
    Catches angels as they fall
    And the all-time winner
    Has got him by the balls
    He picks up Gideon's Bible
    Open at page one
    I think God He stole the handle and
    The train won't stop going
    No way to slow down

     

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