Simple SWR Protection Circuit Easy to build

Posted on Feb 6, 2014

Here is a simple SWR protection circuit you can easily build. The directional coupler and detector components are from an old VHF SWR meter. You may want to replace the meter`s existing RF bypass Capacitors with higher quality (mica) ones. You may also want to replace the line coupler`s termination Resistors which higher wattage ones. Be sure to us

Simple SWR Protection Circuit Easy to build
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e the exact same value, or the SWR meter will be inaccurate. Also, be sure to use non-inductive Resistors (carbon-film or metal-oxide will work). This then feeds to all LM3914 bargraph display to light the LEDs, indicating the current SWR ratio. SWR When the ratio reaches approximately 3, it will engage the relay, cutting off the RF input to the power amplifier. You could also just a LED light or sound an alarm if you want to. Visit this links for more, 4W FM Transmitter Directional Coupler with RF Filter for 88-108 MHz - 100w LCD PIC16F88 SWR Meter for VHF- UHF and click this link for building: The Windows ® program for drawing analog meter scales.

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