A view of the minidin connector, as seen looking at the pins.
The voltage at the Forward and reflected pins is proportional to the voltage on the coax line, which is proportional to the
square root of the power in the coax.
Use the following calibration for the sensor output voltage for HF-1 and UHF-1 sensors:
100 watts = 2.82 volts at the pin.
10 watts = 0.891 volts
1 watt = .281 volts
The calibration is the same for both the forward and reflected power.
NO supply voltage is required for WaveNode sensors.
Schematic of the WN Input circuit :
The schematic above shows a 4:1 divider and decoupling circuit to interface to an A/D converter. The WN-1 A/D converter uses a 0-4 volt
input range, but you can change the divider ratio to accomodate a different A/D converter by changing R171. Note that R173 and C143
form a lowpass filter to keep RF out of the opamp buffer. The output impedance of the sensor outputs is 10K ohms.
The opamp can be any Rail-rail input/output opamp. We use a Texas Instruments TLC2272, easily available.
You use the same buffer circuit for both outputs of the sensor. You do not need the reflected power unless you wish to calculate the VSWR on the coax.