A power monitor comprising: a coupler (301, 302) configured to sample radio frequency ("RF") power propagating in one direction on a transmission line between a RF transmitter and an antenna, said RF power having a level, said coupler is configured to generate a RF voltage proportional to said RF power level; a power splitter (305, 306) configured to receive said RF voltage and output said RF voltage to a test port (310, 311) and a detector (315, 316); said test port having a known mathematical relationship with said transmission line; said test port is configured to connect to a reference power meter; said detector (315, 316) is configured to convert said RF voltage to an analog DC voltage; a calibration adjustment means (130, 131, 330, 331, 430, 431) configured to output a signal; an analog to digital converter (325, 425) configured to receive and convert said analog DC voltage and said calibration adjustment signal into a digitized DC voltage and a digitized calibration adjustment signal, said analog to digital converter sends said digitized DC voltage and said digitized calibration adjustment signal to a correction circuit (335, 435); said correction circuit is configured to apply a gain ratio correction to said digitized DC voltage, thereby producing a corrected digitized DC voltage, said correction circuit is further configured to output said corrected digitized DC voltage to a digital to analog converter (345, 445), said gain ratio correction is dictated by said digitized calibration adjustment signal; said digital to analog converter is configured to convert said corrected digitized DC voltage into a corrected DC voltage; a power calibrated output (355, 356, 455, 456) configured to output said corrected DC voltage; wherein said calibration adjustment means is adjusted by: connecting a reference power meter to said test port; using said reference power meter to obtain a RF power level measurement from said transmission line while said RF transmitter is broadcasting live at its standard power level and frequency; comparing said RF power level measurement with said corrected DC voltage received from said power calibrated output; when said corrected DC voltage compares unfavorably with said RF power level measurement, adjusting the output of said calibration adjustment means such that said corrected DC voltage compares favorably with said RF power level measurement. a coupler (301, 302) configured to sample radio frequency ("RF") power propagating in one direction on a transmission line between a RF transmitter and an antenna, said RF power having a level, said coupler is configured to generate a RF voltage proportional to said RF power level; a power splitter (305, 306) configured to receive said RF voltage and output said RF voltage to a test port (310, 311) and a detector (315, 316); said test port having a known mathematical relationship with said transmission line; said test port is configured to connect to a reference power meter; said detector (315, 316) is configured to convert said RF voltage to an analog DC voltage; a calibration adjustment means (130, 131, 330, 331, 430, 431) configured to output a signal; an analog to digital converter (325, 425) configured to receive and convert said analog DC voltage and said calibration adjustment signal into a digitized DC voltage and a digitized calibration adjustment signal, said analog to digital converter sends said digitized DC voltage and said digitized calibration adjustment signal to a correction circuit (335, 435); said correction circuit is configured to apply a gain ratio correction to said digitized DC voltage, thereby producing a corrected digitized DC voltage, said correction circuit is further configured to output said corrected digitized DC voltage to a digital to analog converter (345, 445), said gain ratio correction is dictated by said digitized calibration adjustment signal; said digital to analog converter is configured to convert said corrected digitized DC voltage into a corrected DC voltage; a power calibrated output (355, 356, 455, 456) configured to output said corrected DC voltage; wherein said calibration adjustment means is adjusted by: connecting a reference power meter to said test port; using said reference power meter to obtain a RF power level measurement from said transmission line while said RF transmitter is broadcasting live at its standard power level and frequency; comparing said RF power level measurement with said corrected DC voltage received from said power calibrated output; when said corrected DC voltage compares unfavorably with said RF power level measurement, adjusting the output of said calibration adjustment means such that said corrected DC voltage compares favorably with said RF power level measurement. connecting a reference power meter to said test port; using said reference power meter to obtain a RF power level measurement from said transmission line while said RF transmitter is broadcasting live at its standard power level and frequency; comparing said RF power level measurement with said corrected DC voltage received from said power calibrated output; when said corrected DC voltage compares unfavorably with said RF power level measurement, adjusting the output of said calibration adjustment means such that said corrected DC voltage compares favorably with said RF power level measurement.