©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
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
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