The Astro-Tech Voyager #ATVEXT extension tube is an 8” long by 3.22” diameter (206mm x 82mm) tube that threads between the current Voyager mount’s tripod and altazimuth slow motion control assembly. The extension tube adds 8” to the height of the Astro-Tech Voyager mount for more comfortable viewing with long focal ratio refractors, as well as providing more observing comfort for tall observers using short focal ratio refractors and catadioptric scopes. It puts the pivot point of the mount’s dovetail as much as 58.5” above ground level.
The walls of the aluminum extension tube are 0.45” thick for strength and rigidity. The tube weighs a little over three pounds. This adds extra stability to the mount when using heavy optical tubes, particularly when the Voyager mount’s arm installed in either of the 45° mounting positions. The tube is anodized matte silver inside and out for good looks and long life.
To install the extension tube, the Voyager mount’s slow motion assembly and arm are first removed from the chrome adapter ring on the head of the Voyager tripod. This is done by loosening the three set screws in the chrome ring and unscrewing the slow motion assembly.
The bottom end of the extension tube has male threads. These thread into the internally-threaded chrome adapter ring on top of the tripod in place of the removed slow motion assembly. Once the extension tube has been fully threaded into the adapter ring, the ring’s set screws are retightened to lock the extension tube firmly in place with no danger of unthreading. The adapter ring’s set screws engage a recessed groove in the fully threaded-in extension tube so there is no danger of damaging the extension’s threads when tightening the set screws.
Please note that the interior of the tripod’s chrome adapter ring must be internally threaded to use this extension tube. The first run of Voyager mounts used an internally smooth adapter ring, as shown below. Be sure you have the current internally-threaded version of the Voyager mount before ordering this extension tube.
Once the extension tube has been threaded into the chrome adapter ring and locked in place, the mount’s male-threaded slow motion assembly is threaded into the female threaded top of the extension tube. Once it is fully threaded in, three set screws at the top of the extension tube are tightened to lock the slow motion assembly firmly in place. As with the set screws in the chrome adapter on the tripod, the set screws in the extension tube engage a recessed groove in the slow motion assembly so there is no danger of damaging the assembly’s threads when tightening the set screws.
The extension tube can be left in place permanently, but can always be removed easily at a later date if so desired.
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