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Sunday, April 27, 2008

A Simplified CW keying monitor

My homebrew CW station shown at
includes a control (speaker/power supply/TR switch) box. I found, though, that I still needed some sort of CW monitor. The June 1952 issue of CQ magazine describes a simplified CW keying monitor using only 6 parts. Basically it is a neon bulb type audio oscillator keyed by a second neon bulb energized by transmitter RF. I built the circuit into my control box coupling the monitor output to the grid of the 6F6 audio output stage. I added a 12 Meg resistor from B+ to the junction of the two neon bulbs to help reduce motorboating when the circuit is not energized.

It works fine. Now I can silence the receiver on transmit and have the CW monitor to listen to my own fist.