Model 1200K/1210K - RCI SNG ANTENNA SYSTEM
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Operation and Maintenance Manual
SECTION 1 - OVERVIEW
TECHNICAL DESCRIPTION
The 1.2M SNG Antenna System is an elevation over azimuth positioner featuring the simple,
rugged Roto-Lok® drive system which produces very low backlash, high-stiffness and high-
reliability and driven by a low backlash, gear box with DC motors. All drive components are high-
strength steel, housed in lubricated-for-life housings which results in the most reliable, no
maintenance system with the minimum of weight. The reflector is an offset, prime focus, carbon
fiber reflector illuminated by a corrugated feed horn. The RF power amplifier may be installed on
the feed boom, positioner backing structure or inside the truck. Handcranks across az and el axis
are included allowing easy antenna positioning if the controller malfunctions. The basic 2-port
antenna system weighs only 117 pounds.
RF SYSTEM
The offset reflector/feed system produces co-polarization patterns that easily meet the 29-25 log
theta requirement. The .8 f/d optics reduces off-axis cross-pol in the asymmetrical plane. The RF
power amplifier may be installed on the feed boom, positioner backing structure or inside the truck.
Waveguide run to power amp across each axis can be via twist-flex or rotary joints. The system
can be configured for either 2-port or 4-port.
ROTO-LOK® DRIVE SYSTEM
The patented Roto-Lok® drive system utilizes highly-reliable aircraft control cables in a redundant
configuration to achieve a zero-backlash, light-weight, very stiff drive system. It achieves this high-
tech performance using low-tech components by simply wrapping the cable around the driver
capstan several times before wrapping the larger drive drum. The method used to wrap the
capstan results a minimum free-length of cable. The load in the cable on the main drum is
exponentially reduced as it is wrapped around the drum. Therefore the total elongation of the
cable when under load is minimized. The Roto-Lok® system results in stiffness of up to 10 times
that of comparable gear or harmonic drive systems. The cables are pre-tensioned and spring-
loaded at the main drum attachment point, which eliminates backlash at installation and from any
unexpected cable stretch in the future.
