CW Monitor

One accessory that I needed for my station was some sort of keying monitor. I found that keying my transmitter typically overloaded the receiver. In order to hear my own sending I had to listen to the receiver grunt and grown. The "Monitone" CW keying monitor was popular in the late 40s and early 50s. One place it is described is the 1950 ARRL Handbook. It used a 6J5 as a RF actuated code oscillator and a 6SL7 as an audio amp and switch between receiver and code oscillator/monitor audio. I eliminated the receiver audio/switch feature and used a single 6SL7 as an RF actuated "neon bulb" oscillator and audio amplifier. I added a tuned input circuit, adjustable/biased input to control the oscillator, speaker and an internal/self contained power supply.

Typically the only antenna required is a wire in the vacinity of the transmitter or feed line. Without any signal, adjust the bias so that the monitor is silent. After tuning the monitor to the transmitter frequency, keying the transmitter should fire the neon bulb and produce a monitor tone.

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