RF_SENSING_TB_SWITCH

Published:2009/7/13 23:43:00 Author:May | From:SeekIC

System detects presence of RF at output of transmitter and changes antenna connection from receiver to transmitter instantly and automatically. No modifications are required for transmitter or receiver. RF voltage divider R1 permits use with transmitters of any power. Broadband amplifier Q1 feeds voltage doubler CRl-CR2 through broadband toroidal step-down transformer T1.CR6, R7, and R6 form adjustable timing network that governs hold-in time of relay K1. Inverting amplifier U1 turns on Q2 for energizing K1 and switching antenna to transmitter when RF is sensed. When no rectified RF reaches UI, Q2 is cut off and antenna is changed over to receiver. RFC1 and BFC2 have 42 turns No. 28 enamel on Amidon FT-50-43 core, T1 uses Amidon FT-50-43 core, with 25turns No. 28 enamel for primary and 5 turns No. 28 over this for secondary.-D. DeMaw and J. Rusgrove, An RF-Sensed Antenna Changeover Relay, 0ST, Aug. 1976, p 21-23.



Reprinted Url Of This Article:
http://www.seekic.com/circuit_diagram/Control_Circuit/Switch_Control/RF_SENSING_TB_SWITCH.html

Print this Page | Comments | Reading(3)