The Meade ETX-125TB and the Terabeam SAT
In early 2000, Meade Instruments Corporation agreed to manufacture the ETX-125TB optical tube assembly (OTA) for Terabeam Networks, a laser-communications equipment maker and internet service provider.
The ETX-125TB OTA is a white-painted version of Meade’s well-made, blue-anodized ETX-125 Maksutov-Cassegrain. Terabeam mounted the OTA in a gimbal and used it as the receiving aperture for the SAT (Single Access Transceiver).
The SAT was a near-infrared laser transceiver built for point-to-point links through office windows, across the air space between buildings. It could send data at 125 Mbps and receive at up to 1 Gbps.
Terabeam installed SAT units in free-space laser networks in cities including New York, Seattle, Denver, Los Angeles, and Dallas.
Why the product was discontinued
The Terabeam SAT link was a more expensive higher bandwidth solution competing lower-bandwidth microwave transceiver links. When the telecommunications bubble burst in 2000, a less expensive free-space laser product was needed to compete. Terabeam responded with the Elliptica transceiver.
Merger and surplus scopes
In early 2004, Terabeam Networks merged with radio-frequency vendor YDI Wireless (now Proxim Wireless). The merger ended the Terabeam laser-transceiver line. SAT units and leftover Meade ETX-125TB optical tube assemblies (OTAs) soon appeared on internet auction sites.
Because the ETX-125TB was built to sit inside the SAT, Meade did not supply the usual black plastic backs or mounts. The rear outer diameter of the aluminum tube was never machined to accept that plastic back, and the focus shaft was shortened for the SAT. Even if someone forced a Meade plastic back onto the tube, a standard focus knob would not fit.
Making the Meade ETX-125TB usable again
Wegat Optical developed an adapter so owners could attach 2-inch accessories of the kind used on Schmidt-Cassegrain telescopes.
Similar adapters were later made for the Meade ETX-90 and ETX-105 of the same era. The ETX-105 adapter accepts 2-inch Schmidt-Cassegrain accessories. The ETX-90 version keeps compatibility with the smaller original Meade ETX accessories.
Meade Terabeam ETX-125TB Optical Tube Assembly
The white ETX-125TB Catadioptric Maksutov-Cassegrain was designed, built, and aligned by Meade Instruments for Terabeam Networks in 2000. Although similar to Meade’s commercial telescope, these OTAs include several quality upgrades.
Dimensions:
- 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 laser communications, LIDAR, astronomy, astrophotography, and general photography. At about 8 pounds, it makes a great grab-and-go telescope.
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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