In early 2000, telescope manufacturer Meade Instruments Corporation entered into an agreement to manufacture the ETX-125TB telescope for the laser communications equipment manufacturer and Internet service provider Terabeam Networks.

The Model ETX-125TB OTA (Optical Tube Assembly), which was a white painted version of the well-made blue anodized Meade ETX-125 Maksutov-Cassegrain telescope, was employed in the Terabeam application by mounting it on a gimbal and utilizing it as the receiving aperture for the Terabeam SAT (Single Access Transceiver) product. The SAT was a near-infrared laser transceiver designed to establish point-to-point communication links through office windows via the air space between buildings. The SAT had the capability of sending data at a speed of 125 megabits per second and retrieving data at rates of up to one gigabit per second.

Terabeam installed the SAT into free space laser communication networks in many cities, including New York, Seattle, Denver, Los Angeles, and Dallas. Unfortunately, the Terabeam link was tens of thousands of dollars more costly than lower bandwidth microwave transceivers. After the telecommunications bubble burst in 2000, there weren’t many customers willing to invest in a free space laser Internet connection, so Terabeam developed the smaller and less expensive Elliptica transceiver (shown below).


In the first few months of 2004, Terabeam Networks merged with radio frequency solutions provider YDI wireless (now Proxim Wireless). As a result of the merger, the Terabeam laser transceiver products were discontinued. The SAT transceivers and the unused inventory of Meade EXT-125TB telescopes soon found their way to Internet auction sites.

Since the ETX-125TB was originally meant to integrate into the Terabeam SAT, there were no Meade black plastic backs or mounts provided to Terabeam with the telescopes. As a consequence, there was no need to machine the outer diameter of the rear of the aluminum tube to allow for the plastic back to easily slide onto the ETX-125TB. The focus shaft was also shortened for the SAT application which prevented the use of a focus knob if one was able to force a Meade black plastic back onto the rear of the EXT-125TB. To make the ETX-125TB useable once again, Wegat Optical developed an adapter that would allow owners of these telescopes to attach 2-inch accessories like those used on Schmidt-Cassegrain telescopes. Similar adapters were also created for the Meade ETX-90 and ETX-105 telescopes of the same era, but with the notable exception that while the ETX-105 adapter allows for use of 2-inch Schmidt-Cassegrain accessories, the EXT-90 compatible version of the Wegat Optical adapter retained the ability to attach the smaller Meade ETX accessories.

Meade Terabeam ETX-125TB Optical Tube Assembly

The White ETX-125TB Catadioptric Maksutov-Cassegrain telescope was originally designed, built, and aligned by Meade Instruments for Terabeam Networks in 2000. Although similar to Meade’s commercial telescope, these OTA’s include several quality upgrades.


  • Length: 13 Inches (330 mm)
  • Outer Diameter: 5.75 inches (148 mm)
  • Clear Aperture: 5 inches (127 mm)
  • Secondary Mirror Obscuration: 1.55 inches (39.4 mm)
  • Focal Length: 74.8 inches (1900 mm)
  • Adapter Flange Focal Distance : ~3 inches (76 mm)

Special Custom Features:

  • Finer focus control than standard ETX-125
  • Extended rear baffle design
  • Protective dust cap for the rear of the telescope
  • Larger focus knob for more comfortable grip
  • Wegat Optical custom black anodized 2-inch Accessory Adapter

The ETX-125TB OTA is suitable for use in laser communications, LIDAR, astronomy, astrophotography, and general photography applications. With a weight of about 8 pounds, it makes a great “grab and go” telescope.

Wegat Optical has since designed a Meade ETX-90 adapter that allows for the use of standard ETX accessories and a Meade ETX-105 adapter that allows for use of 2-inch Schmidt-Cassegrain accessories. By removing the focus knob, black plastic back, and fork mount from the optical tube assembly, a Wegat Optical adapter can be easily attached to any Meade ETX-125 telescope, ETX-105 telescope, and most ETX-90 telescopes manufactured prior to the Meade Observer Series.

Wegat Optical accessory adapter kits have been used to retrofit optical tube assemblies and create many impressive customized telescopes. View Gallery >

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