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RF Actuated Keying Monitor
Sending Morse on a rig without a sidetone is not impossible, but is not
particularly pleasant either.
This battery-powered monitor has been designed to provide an audible
indication of keying for those whose rigs lack a CW sidetone. Its sensor wire is wrapped around the
transceiver's coax – no direct connection is required. Of course Morse isn't the only use for this
nifty circuit – it should also be useful any time you need a simple alarm that
detects the presence of RF.
RF collected at the sensor wire is rectified by a germanium diode. This produces a DC voltage that triggers a
transistor switch. This then turns on a
555 audio oscillator that drives a speaker.
Items were chosen for likely usefulness and a satisfaction rating of 4/5 or better.
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