Spring 2007 Issue

The Ladder Tower
A Simple Antenna Structure

Are you in a hurry to get on the VHF-plus ham bands and don’t have the wherewithal to put up a conventional tower? Here W8FR offers a possible solution—an extension ladder.

By Fred Race, W8FR

Photo 1. The ladder tower.

These days many hams are seeking ways to improve their reception and up their signal strength while being limited or modest in their antennas and antenna-related structures. An easy way to get some short-boom UHF/VHF antennas “up” is by constructing and using a ladder tower. Photo 1 illustrates an installation with three antennas at nearly 30 feet.

The ladder tower isn’t a new idea by any means, as it is one of several wooden tower structures of early ham radio days, when even rotary-beam antennas were mounted on a wooden framework using stand-off insulators. When you don’t want/need, or just can’t invest in, a conventional structure (sections of Rohn 25G, etc.), look to your hardware store for an inexpensive aluminum extension ladder. A convenient length is 12 feet, with extension to 20 feet plus, depending on your load. The ladder used in photo 1 supports 225 pounds, is lightweight, and is of sturdy construction.

The method of attaching the ladder tower to the house is simple and somewhat unique. The overhang attachment uses two mounted 6-inch, heavy-barrel bolts that can be positioned to hold the ladder tower in place and locked on either side of the ladder. Simple 3/8-inch holes were drilled in each side of the ladder and the bolts slid through to hold it in place. Six 3-inch drywall screws hold each barrel bolt in place. Using U-bolts to attach the ladder tower to the base is very simple: Two 13/4-inch steel post pipes at 16 inches each were set in the ground, while one bag of quikcrete mixed to a slurry was poured and dried for three days. Photos 2 and 3 illustrate these attachment points for the ladder tower.

Let’s start with the overhang and base preparation. The overhang is prepared with one 36-inch treated 2-by-4 to span three roof-rafter ends. Three-inch dry-wall screws are used to attach the 2-by-4 through the flashing, and it provides the mounting surface for the two upper ladder-tower barrel bolt mechanisms (right and left sides of the ladder to hold it to the house). A hole is dug down to around 12 inches in a rectangular shape extending about 4 inches beyond the ladder width, with a front/back depth of 6–8 inches to accommodate the base attachment scheme.

Positioning and “plumbing” the ladder is simple, but done in a prescribed manner. First, the ladder is set into the hole (hole dug/centered beneath the overhang attachment point) to enable driving the two pipes in on either side of the ladder to a depth of 8 inches, while holding the ladder plumb (photo 4). This is a two-man job, and three might even be better. Once one is driven in, shift to the other side while maintaining plumb and drive in the other base pipe. Work in construction stops at this point to allow the concrete to set (three days).

After the base concrete sets, reposition the ladder to plumb, and with it setting on the concrete, mark each side for U-bolt holes; one is sufficient. This is accomplished by placing the U-bolt over the pipe and against the ladder side at a point on the pipe. Draw around the threaded shanks on either side of the pipe. When you are ready to drill the holes, use a centerpunch to mark in the center of the drawing circles. All the holes in the ladder, including the rotor base pipe holes, are marked and drilled later.

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