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FM transmitters field strength meter

2016-04-09 02:50  
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This Field Strength Meter has been specially designed for our FM bugs. It is capable of detecting very low power transmitters and will assist enormously in peaking many of our FM transmitters that have a coil in the output stage that can be adjusted for optimum output. field strength meters have only been able to detect transmitters with an output of 100 milliwatts or higher, and for an output such as this, a simple circuit such as a meter and a coil is sufficient.TL081  (IC1 op amp is used to increase sensitivity. RF signal is detected by CR1 and is then amplified by IC1.Full-scale sensitivity is set with the 100 potentiometer.The circuit consists basically of an RF amplifier, diode rectifier and a DC amplifier.The RF amplifier has been designed to only have a gain at high frequencies.
 

High-sensitivity field strength meter