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Model Number: 490S1
Manufacturer COLLINS
Alternate Part Number
National Stock Number
Categories Coupler, Antennas
Repair Capabilities YES
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Product Details
The 490S-1 HF Antenna Coupler provides the proper impedance match between an aircraft shunt or notch antenna and the 50-ohm impedance of the transmission line. The 490S-1 operates for both transmit and receive with a voltage standing wave ratio of not more than 1.3:1 throughout the specified frequency range. The 490S-1 dual system is capable of operating using a common antenna with two transceivers. Three decisions are made by the 490S-1 logic that determine if both couplers are in a receive mode, if one coupler is in a transmit mode, and which coupler received a key (ground) first. The 490S-1 is a lightweight pressurized unit with a removable cover containing a seal gasket. The 490S-1 consist of an electrical equipment case, radio frequency tuner module, loading-phasing discriminator module, control logic card, interface logic card, servo-amplifier card, and power supply/isolation amplifier card. The 490S-1 must be mounted on a 790S mount for proper interface with the aircraft. The 490S-1 is held in the mount by two quick-disconnect captive front clamp. The 490S-1 is tunable over a frequency range from 25 to 30 MHz, and contains the necessary switching and interlocking circuits for use in either a single or dual system ARINC configuration. When a dual system is used, interlock circuits prevent one system from being keyed or turned while the other system is either keyed or tuned. A failure in one system will not preclude the operations of the second system. The 490S-1 uses the 115-V 400-Hz aircraft power and has no special cooling requirements and there are no controls on the 490S-1.