The voltage and current detector is built in an Original size FLEXI-BOX on a dedicated PCB. The RF connectors can be selected from BNC, N, TNC or SMA. The box has one 50Ω input and one 50Ω output and is inserted inline to the coaxial cable under test. Four 1 mm sockets are provided for monitoring the rms voltage and current with a DMM (the current being monitored as a related voltage). The DC input can be fitted with a feed through capacitor with a solder tag. This is intended as a measurement aid and is also part of the "Standing Wave Kit". This is a unique piece of measuring equipment and has good educational potential. It is also possible to use it for fault finding as a RF signal detector especially if it is fitted with a BNC connector, because then a X1 oscilloscope probe can be plugged straight in. It makes a very cheap RF power meter if you do not mind a doing some calculations and have an accurate 50 Ohms load to hand.
The circuit uses Schottky diodes to detect both the voltage and current outputs. The measurement principal and the mathematical linearisation of these diodes is described in Understanding Coaxial RF Transmission Lines by Measurement and Calculation Appendix B1
The current output is measured via a transformer that is inserted into the transmission line. The output of this transformer is amplified and the amplifier output level is very similar to the original signal. Thus ensuring that the detector diodes at the amplifier output work over the same voltage range as the voltage detector diodes and therefore have similar linearity.
A selection of escutcheon drawings are available for downloading as .zip or .bmp files.
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