• Tree Antenna Sky Hooks

    From G8MNY@21:5/101 to WW on Thu Aug 29 03:04:33 2019
    G8MNY TECH 28.08.19 06:26l 263 Lines 12021 Bytes #365 (0) @ WW
    BID : 19180_GB7CIP
    Subj: Tree Antenna Sky Hooks
    Path: OK0NBR IR2UBX IW2OHX UA6ADV CX2SA ZL2BAU N9PMO JE7YGF GB7CIP
    Sent: 190828/0912Z @:GB7CIP.#32.GBR.EURO #:19180 [Caterham Surrey GBR]
    From: G8MNY@GB7CIP.#32.GBR.EURO
    To : TECH@WW

    By G8MNY (Updated Jul 09)
    (8 Bit ASCII graphics use code page 437 or 850, Terminal Font)

    There are several ways to put a rope in a tree...

    BOW & ARROW
    The normal arrow is too light to pull up much so adding a weight to the point will greatly help, suitable are a layer or two of Pb solder/steel/Cu wire tightly wound on to double or treble the weight of the arrow.

    No ,,,,,,,, /////////
    Point (░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░│░░░░░░░░░░░░[
    '''''''' \ \\\\\\\\\
    Weight `\ Thin string or
    `-._ Fishing line

    No point is needed, as there is a danger it could hit someone or get stuck firm in the tree bark. Attach a thin string or thin fishing line to the rear of the arrow. Estimate how much line is needed to do the shot & unravel that amount in neatly & untangled front of you, if ground is too rough spread it out on a tarpaulin etc. When placing the arrow in the bow make sure there is no risk of line entanglement with you or the bow.

    What to aim for.
    /'~`\ \/ \/
    .-'~`·. L A R G E \ Tree \\// `\
    / TREE `\ T R E E \ Branch// `\
    || `\ Aim | | |Aim || `\Aim

    1/ Aim shot to either clear the whole tree, if you can get to the other side.

    2/ Or aim much steeper, to fall into the top of the tree so that line falls
    through middle of tree canopy,

    3/ Or over a suitable branch if your aim is good.

    Done in the winter with no foliage, you can see far more of what you are doing. N.B. Thick foliage also grabs the line making the arrow difficult to free up so that gravity does the work.

    CATAPULT
    This is much the same as for the bow & arrow, but you must use thin fishing line, then pull over a thicker line. The shot weights (tear drop shaped or just cubes of lead (10-15mm sides) with a hole drilled through it, are small & not very visible, so use brightly coloured ones e.g. Orange/Red not green/yellow/ brown, as this will help spotters the other side of the tree to see the shot. As with bow & arrow a heavier weight is need if there is sticky leaves or soft bark that "grab the line" & then you can loose some line & the weight.

    The knot must be a suitable type for mono filament that does not over stress (knot) the load carrying side, I found several (at least 3) simple loop knots work on the fee end around the incoming line (see insulator & eyelet diagram below), & can be undone with patience.

    The pre-laying out of unknotted line is very important, but I have seen combined fishing reels used (on handle) with only occasional line fouling.
    _
    Tube /~/~\
    ╔═==============( ░░░░│ Flatted Sling stretched
    Y Steel ║ Rubber Shot\_\_/ leather/Rubber to here to fire!
    ║ ~ sling
    ║│
    │~│
    │ │
    │_│Handle

    I have seen this method used for a very cluttered site, with great success getting over specific tree tops/branches at 40m up & clear 30m depth of forest at the same time. With the fine line needed for log shots, windage is a problem, & must be considered when aiming so the line drifts into the tree as needed.
    Often a high shot is best coming down in the tree if you can't reach the other side of the tree!

    FISHING ROD
    Similar to both of these methods is casting a weight over a tree. Again a far degree of skill is needed to get the line & weight over the part of the tree needed as there is no aiming system with a fishing line. But the range (possibly not height unless you stand on steps for more room) may be well over other methods!

    TWIRLING (Slingless shot)
    This method uses stronger line & heavier weight & for temporary aerials attached to the same line is actually the quickest system.
    A weight 100gm, e.g. plumb bob is tied to nylon cord (e.g. builders orange marking line) & make sure the fixing is very good & will not pull out of the weight, & then with a meter of line to the weight you twirl this around in a vertical manner in line with the target. Your hand needs protection & a leather glove must be worn. As there is danger of 'miss fire' is you let go at the wrong time, make sure other people & cars etc. are well clear!

    M E D I U M twirl dia
    S I Z E D . ┌ .
    T R E E . o.
    || v ()/'. `·.
    || . ┼│ .^ `·.
    || / \ pay out line
    all laid out

    Unlike the previous 3 methods your strength timing & skill are more important. Make sure the line is going to pay out freely & that you are not going to get entangled.
    I have put lines into trees at a good 18M with this method. Due to the heavier weight, the tree grabbing problem of the line is less, except for miss fires where the shot has to be pulled from the wrong branch etc. In that case beware of knotting the cord around a branch!
    Often a high shot is best coming down in the tree especially if you can't
    reach the other side of the tree!

    BACK THROW
    Bob VK6BE reminded me there is another method, & that is to stand with your back to the tree & lift a stone in a short line/sling (he suggest a long sock).
    .· .
    M E D I U M .
    S I Z E D .
    T R E E .
    || .
    || O .
    || ▌\\ ,
    || ./\./·

    You effectively turn yourself into a Trebuchet machine. There is a mechanical advantage to this method, as both arms are used & the sling length speeds up the shot. Bob says 60ft can be reached my this method.

    TALL POLE METHOD
    This is a non ballistic method. I use 17m of very thin set of telescoping poles. e.g. poles of 1.25" 1.5" 1.75" & 2" with matching size U exhaust clamps done up over the joins, so that the U is only over the thinner pole & the clamp over the larger one.

    U │ ▌ clamp
    \ │ ▌_/
    (≡≡≡≡≡≡≡≡__│]≡ NUTS
    │5°Angle │Pole
    │pole cut│higher
    │ │

    The top pole then has a Y shaped twig put in it, to take string over the top.

    /Y\ |Y\
    M E D I U M | │ | M E D I U|│M\
    S I Z E D | ║ | S I Z E |D║ \
    T R E E | ▐ | T R E E| ▐ \
    || | ││| || | ││ \
    || Weight 0 ││| || 0 ││ \

    Extend the pole set on the ground (do clamps up as needed) to be taller than the wanted anchor point in the tree. Tie a hefty weight (half brick) to the string & put a long loop of the string over the top pole Y.

    Walk up the fragile set of poles with someone footing the base keeping it on the ground. Carefully position the whole pole against your target point in or above the tree.

    Pull on the free end string to raise the weight to the top. When it is over a suitable branch, lower the weight. With careful jigging the weight should
    come down OK through the tree branches. Avoid knotting it around branches if recovering for a 2nd attempt!

    HALYARDS
    For permanent locations it is desirable to have halyards at each end of HF wire aerials so that they can be lowered for maintenance & tuning up the aerial etc.

    A simple mostly enclosed galvanised cast pulley that has a crude steel pin bearing well need to be greased. (e.g. hot runny grease dripped in to centre axle)

    Cast_ Type Simple Open type Modified
    (0) |~| 0 0 0 0
    ╔═╧═╧═╗ .┴─┴. ┌──╨──┐ ┌╨┐ ╓──╨──╖ _.┌╨┐.Key
    ║ Rope║ / \ │ Rope│ │ │ ║ Rope║ / |│ │| \
    ║│\_/│║ | | ││\_/││ /'│ │`\ ║│\_/│║ | │ │ |
    ║│ | │║ | | ││ | ││ | │ │ | ║│ | │║ | │ │ |
    ╠╡ | ╞╣ | * | ╞╡ | ╞╡ | │o│ | ╠╡ | ╞╣ | │o│ |
    ║│ | │║ | | │ | │ | ~ | ││ | ││ | ║ |
    ║│/~\│║ \ / │/~\│ \ ___ / ││/~\││ \_ ║ _/
    ╚═╤═╤═╝ `─┬─┬─' │ │ `-_║_-'
    (o) |_| slotted plates
    ~
    On simple open ones where there is a real chance of the rope fouling when it come off the pulley, I found that a piece of suitably cut tin plate could be added to each side of the pulley block wheel to stop the rope fouling & jamming the pulley by falling off the side of the wheel. The slotted plates have a key cut at the top to locate the inverted U bracket, they also have bent back edges to be smooth to the rope.

    Much better & more expensive types are available from boat chandlers.

    The halyards are threaded up to be continuous loops so that if the aerial breaks then it can still be lowered. Also for the tree end there is a put up rope that was placed over a high branch to hall the halyard pulley up.

    Polypropylene rope (e.g. 6mm draw rope) is OK, but does have a short lifetime of only a few years in the sun before it disintegrates! Never trust it for dangerous work where people could get hurt!

    Tree.....Pulley Spring
    : O.......eee.∞----
    : : / Insulator
    : : / Loose
    : : / Pull Down
    : : / Loop
    : : /
    : Tension
    Tie Off Weight

    Note the initial pull up rope will soon be overgrown into the tree bark & the pulley will not be recoverable after a few years.

    INSULATORS
    For fair Wx /P activity end insulators are not needed as dry string, nylon, or polyprop, are all excellent insulators at ham QRP levels ( 1kW). But in permanent & for wet conditions good insulators are needed as arcing/losses could occur, especially in coastal sea spray areas.

    .===-.. ... =:\
    / _ `\\. /'_ """\\\
    ==////=======) │ \\\\\==== ======/////===) │ \\\\\=======
    \ " .// \ " __.///
    `====:' `""" =:/
    R I G H T W R O N G

    Black plastic egg insulators are ideal for the middle of a dipole where low weight is important & due to the low the Z the insulation requirements are minimal. Ceramic ones are best used at the ends were their weight is less important & will not reduce the aerial's height by as much.

    With tough wire a tight wrap of the tail end may be adequate, but for the rope or thin wire then self tightening knots that do not knot the tensioned feed line should be used. This is an ugly but safe knot system....
    _
    free end ___ ___ ___ /~ ~\
    ==/.-.\=/.-.\=/.-.\==' eye-│
    ==============│││===│││===│││===. let │
    Load cord \│││/ \│││/ \│││/ \_ _/
    self tightening granny "
    knots in free cord

    TENSIONING
    To maintain & control tension on a permanent installation, I use a 10kg heavy weight (old transformer). But I found this was not too effective, because the mass & the pulley friction would be slow at keeping the tension, resulting in the middle of the aerial bobbing up & down with the wind. So I tried adding some long coil springs out of a chest exerciser (was not mine) or cow fence types used in line with the aerial give quicker strain relief (no mass) than the tensioning weight, & maintain aerial tension better. I painted these to reduce further rusting & one mounted each end just before the insulators. This has stopped the bobbing around as about 0.5m stretch is available with no slow mass to allow for the wind & tree sway. A bunjee may have similar performance, but a short lifetime!


    See my TECH bul on "Casting Lead Throwing Weights"


    Why Don't U send an interesting bul?

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