H.F. RECEIVING ANTENNA MULTICOUPLER
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MA.174 H.F. RECEIVING ANTENNA MULTICOUPLER |
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The Racal Receiving Antenna Multicoupler type MA.174 has been designed for use in h.f. receiving systems employing a number of receivers, especially where many directional antenna systems are employed and space is limited. The multicoupler will feed up to eight receivers from one antenna, thus eliminating the duplication of antenna systems.
Wideband coupling is employed, therefore no tuning is necessary. All output sockets may be used at any frequency in the range 2 MHz to 32 MHz. A test meter is provided for checking all circuits.
The MA.174 is designed for standard rack mounting with a front panel height of 178 mm. (7 in.). The equipment is divided into sub-assemblies for simplicity of maintenance and accessibility. It is self-contained with its own built-in power supply. Input and output sockets are all Amphenol type UG/109-4.
The MA.174 is intended for use from a single antenna input of 75 Ohms impedance.
Input signals are passed to a high pass filter with a sharp cut-off at frequencies lower than 2 MHz, thence to a push-pull distributed amplifier, composed of cascode connected stages. A single output feeds a hybrid resistor and transformer network to provide the eight separate receiver outlets.
The filter system attenuates signals below the pass-band, thus reducing the effects of cross-modulation which could occur due to local transmissions below 2 MHz. The design of the amplifiers enable them to handle signals over the complete pass-band with the minimum generation of intermodulation products. The use of a balanced hybrid network for the output circuits ensures an isolation between adjacent outlets of better than 30 dB.