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©2018 F. Dörenberg, unless stated otherwise. All rights reserved worldwide. No part of this publication may be used without permission from the author.


Latest page update: 11 November 2018


under construction

INTRODUCTION


To be covered:

  • Background, my local conditions, why I "need" a telescopic mast, height of interest, to be used with which antennas (dipole, large STL, small STL,...).

THE GEROH 6M (20 FT) MAST


general (German army surplus, 5 sections, cable, hand crank), photo of collapsed mast, construction cross-section, accessories, geroh clamps, top hole, adapter stub for STL, adapter stub for rotor, adapter stub for dipole



ADAPTER STUBS

Mast accessories bag includes an insert; dimensions of insert, size/depth of hole in top of mast + securing bolt. Need insert stubs for large STL, small STL, rotary dipole.

Large STL: 3-part; 59mm OD Alu rod (for 63mm OD PVC tube mast of STL) + steel washer + 26mm OD Alu rod , 12mm thread in rods for steel threaded rod. Alu because of weight, cost, ease of machining. Standard off-the-shelf diameters where possible, to reduce/avoid machining.

Small STL: 2-part: 40mm OD Alu rod (for 42mm OD PVC tube mast of STL) + 26 mm OD Alu rod, 12mm thread in rods for steel threaded rod.

Rotary dipole: top mast of rotator limited to 1.75", 35mm OD POM rod (OTS diameter) + 26 mm POM rod , 12mm thread in rods for steel threaded rod.  Until I get the rotator: 2-part insert.

Insert design drawing

Insert corresponding photos:



GUYING THE MAST



Diagram from manual + own diagram.

At two levels: largest/lowest diam mast section (1m15), top of mast (vriable, with max of 6m). Three directions, 120° apart.

My terrace no lawn --> no spikes. Eyebolt anchors in walls + very solid pergola post.

List of materials (2 eyebolt anchors, 36 m double-braided 5mm special polyester rope (Dyneema) with low elasticity/stretching  (1.5%) and high  tensile ( = breaking) strength (when new) 1100 daN ≈ 1100 kg equivalent 100 kg guying), 9 carabiners, 6 Camcleat line-locks). In my case: not permament installation, so UV resistance is secondary. Boat supply store.

Photo of materials.

Photos of guyed mast



REFERENCES



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