Wire Antenna Tensioners

Our wire antenna tensioner is a high quality variable tensioning device that absorbs the shock on amateur radio antennas when the support trees sway in the wind. It is simple to install, camouflaged, and is designed to control wire tension and minimize antenna sag. Because the Tensioner is spring loaded the tensioning energy is at the tree top. Therefore antennas supported by a Tensioner can usually be placed much higher in a tree compared to antennas tensioned by a counterweight at ground level. The additional height is often 10 to 15’ which will improve your antenna’s performance. Tensioners can also be mounted vertically at ground level or at an angle for inverted Vee antennas.

Two basic models are available. Model 20-50 has a variable tension range up to 50 lbs and Model 30-100 has a range up to 100 lbs. Dimensions are identical. Each basic model has a “Reciprocal” mate that can be optionally used as the second unit in a two Tensioner installation. All models can be mounted vertically or at an angle.


                  Tensioner can be placed higher than a counter weght system

Two Tensioners will double the tree sway distance and make a very rugged and stable antenna installation and is highly recommended. When pulling force is applied to either end of the Tensioner, colored calibration markers exit the barrel at 5 or 10 pound increments depending on the model. The visible markers make it easy to accurately adjust antenna wire tension and sag from the ground. Tensioners are installed in the tree top canopy in series with the antenna and the support halyard. Your antenna wire or its horizontal support line connects directly to the Tensioner’s end insulator. Installation requires just one support halyard that you also use to adjust the antenna’s static (working) tension to any value up to 25 lbs or 50 lbs, depending on model. Tensioners can be used with or without a top pulley on the supported halyard.


Tree supported wire antenna


When the support trees sway in the wind the Tensioner  will “make up” the sway distance and cushion any sudden forces on the antenna and ropes that could cause abrasion and antenna wire failure. The advantage of using two Tensioners is that they will compensate for twice the tree sway displacement of a single unit.


It's what's inside that counts!

Zinc chromate plated springs provide outstanding corrosion protection and service life  

The expansion springs used in Vari-ten Tensioners are not the typical hardware store or garage door opener springs. At the heart of each Tensioner is a very special custom engineered expansion spring designed and manufactured specifically for Vari-Ten to meet the dynamic load and expansion rate needed for proper wire antenna tensioning. Separate custom springs are used in the 20-50 and 30-100 Tensioner models. Each spring has its own static and maximum load characteristics consistent with the design goal of maximizing the free travel displacement within its 50 pound or 100 pound design load range. To accomplish this they are fabricated with special tempered high carbon steel “piano wire” in accordance with ASTM A228 standards  Each spring has been conservatively designed with the maximum load rating being well beyond the maximum load that it will see in actual antenna Tensioner service.  Springs are yellow zinc chromate electroplated for superior corrosion protection. This conservative design philosophy provides an indefinite service life expected to exceed 10,000 full cycle operations.  A full cycle is the complete extension and contraction of the spring at its full rated load.  Occasional very strong wind gusts may result in a full cycle operation but the vast majority of operations under actual operating conditions will be fractional cycles and the spring’s actual service life should be in the range of decades.