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G8MNY > TECH 05.07.05 17:01l 80 Lines 3593 Bytes #999 (0) @ WW
BID : 53030_GB7CIP
Read: DG4NAU GUEST OE7FMI
Subj: A Light 17m /P mast design. 1/3
Path: DB0FHN<DB0MRW<DB0WUE<DK0WUE<7M3TJZ<KP4IG<LA2MV<ON0BEL<GB7CIP
Sent: 050705/0858Z @:GB7CIP.#32.GBR.EU #:53030 [Caterham] $:53030_GB7CIP
From: G8MNY@GB7CIP.#32.GBR.EU
To : TECH@WW
By G8MNY (new Jan 05)
Here is a VERY light weight mast system 20kg (40lbs) I designed & built years
ago, & I have use it most of my for /P. It is much lighter than anything else
of its size. It is very stringy so I called it "STRING WONDER MAST".
PURPOSE OF THE DESIGN
1/ To support an aerial @ 17m (54ft).
2/ Erection possible in cluttered sites.
3/ With modest aerial, One person could operate mast.
4/ Uses manual or Bottom rotor.
POLES
It has 4 section of thin (2-3mm) aluminium tube starting with pole 1 a 3.6m 63m
(12ft 2.5"), then 2 a 4.8m 50mm (16ft 2"), then 3 a 4.8m 43mm (16ft 1.75") &
finally pole 4 a 4.8m 37mm (16ft 1.5"). Finding sources of suitable tube
stockests can be difficult!
GUYING SYSTEM
AERIAL
.'³³'. 4 GUY PLATES GUY & STRING BOBINS
. ³³4 . ÚÄÄÄÄÄÄÄÄÄÄ¿ ____________________
. .'ô'. . ³ o __ o ³ ³ H O L D ³
. . ³³3 . . ³ / \ ³ '\. ./'
. . ³³ . . ³ ³ ³ ³ ³ WaterProof ³
. . .'ô'. . . ³ \__/ ³ ³ GUY WINDER ³
. . . ³³2 . . . ³ o o ³ ./' 1 per Plate '\.
. . . ³³ . . . ÀÄÄÄÄÄÄÄÄÄÄÙ ³____________________³
.. . .'ô'. . .. ----- 10 to 30cm -----
.. . . ³³1 . . .. Largest 1 for top guy set
. . ³³ . .
This uses 4x 10cm (4") square metal plates with central holes to closely match
the poles as all by the top one sit on the larger lower pole. The corners are
drilled to take the 3mm guy nylon strings & all metal smoothed off to not cut
guys.
The 4 sets of guys are 1.6x longer than the height they are used on to ensure a
safe shallow guying angle can be used. I colour coded them with dye per level &
each level is wound on flat winder with the "hold" side marked so that each
twist of 4 guys is unwound next time. The top set needs the largest bobbin! The
top 2 sets can be removed for transport.
IMPROVED TOP GUY SYSTEM
To stop the guys wrapping around the rotating pole that can happen with the top
guys, the guy plate has 2 x 60cm (2ft) coat hanger wires threaded through the
holes as well to make a large spreader, the wires have loops bent the end to
capture the guys strings.
Aerial
³ ³ 1 turn of Coax
PLATE ³ ³ ____
============ coat hanger ./' __ `\ Washer ./\.___
./. ÃÄÄÄÄ´' .\. spreader ./ ./' `\.'\. Tab\/' `\._Screw
./ . ³Clip³ . \. wire ³ ³ ³ ³ ³ ³ ³Up
o/ .³ ³. \o ³ ³ ³ ³ ³ ³_³Clip
. ³. .³ . guy `\ `\.__./' /' /\.___./'
. ³ .. ³ .Nylon `\.____./' `\/'
Aerial Coax Tab
Support Strings
Hanging from this plate is also 2 strings (free ends of 2 of the guys) 60cm
(2ft) long from opposite corners to take the hanging coax weight.
The top plate sits on a washer that sits on a Jubilee clip with 2 flat strip
folded around it to proved a flat surface tabs for the washer to sit on. The
clip is firmly tightened on the top pole below the aerial.
In part 2. Pull up system, Pull up ropes, Locking Catches, Locking location,
& Lubrication.
Why Don't U send an interesting bul?
73 de John G8MNY @ GB7CIP
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