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 produced a DC voltage that triggers a transistor switch. This then turns on a 555 audio oscillator that drives a speaker.
Click here for the schematic diagram for this project
Use the Back button to return to this text.
back to Peter Parker's Project Page
This page was produced by Peter Parker VK3YE (parkerp@alphalink.com.au). The page is continually under construction. Material may be copied for personal or non-profit use only.
