PROTECTION_FOR_ORP_TUNING

Published:2009/6/28 22:41:00 Author:May | From:SeekIC

Simple resistive SWR bridge provides dummy load, relative power output indicator, and safe method of tuning transmitter without destroying transistors because of mismatched load. Input divider R1-R4 has total resistance of 50 ohms, using 1/2-W composition resistors, for dissipating transmitter output when S1 is in TUNE position. M1 indicates relative power applied to this load. Antenna is connected through Transmatch, and antenna tuner is adjusted for minimum deflection or lowest SWR. RE isolates transmitter from antenna. With S1 in OPERATE position, M1 indicates relative power output into antenna.-A S. Woodhull, Simplified Output Metering Protects QRP Transmitters, QST, April 1977, p 57.



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