Note
73, Jan 1973, p. 136.
QST, May 1973, p. 154.
QST, Oct 1974, p. 170.
QST, Aug 1975, p. 161.
The Q-Box is a self-contained, transistorized active audio filter created by Autek Research designed for Novices and serious CW operators.
It provides variable audio selectivity ranging from approximately 2 kHz down to 30 Hz using a simple twist of a control knob. It passes tones near its 800 Hz design frequency while rejecting all others (such as nearby QRM).
The Q-Box requires no power from the receiver, running instead on an internal 9V battery. It plugs directly into a receiver's headphone jack, and headphones are plugged into its output. It has no insertion loss and produces enough output to drive headphones or an external speaker amplifier.
Field testing showed that it acts as an effective trimming selectivity control, helping pull weak signals out from under strong QRM. Unlike fixed surplus toroid filters that must be switched fully in or out, the Q-Box's gradual application allows users to maintain a balance between sharpness and tuning ease as band conditions dictate.