The QNC (QRM Noise Canceller) is a radio frequency device in the Short Wave Broadcast band or alternatively the Amateur (Ham) Radio HF bands that eliminates or reduces power line noise, computer noise, TV-generated interference, and other types of electrical interference. The QNC unit connects right to the antenna connector of the receiver or transceiver to cancel locally generated noise before it gets into the receiver and affects the receiver’s AGC circuits. Reception of signals well below the noise level of the local interference is possible.

To cancel locally generated interference, the QNC detects the interfering signal and adjusts its phase and magnitude so that it matches the offending interference at the receiver input, but is 180 degrees out of phase, effectively cancelling the interference. This scheme is particularly effective at reducing local power noise or other locally generated noise types.

Front panel controls allow adjustment of both the phase and magnitude of the local interference, providing extremely deep cancellation of the offending interference.

The QNC connects between the main station (outside) antenna and the receiver’s antenna connector. A simple second antenna (usually a short piece of wire) connects to the QNC to act as a noise pickup antenna. This short wire antenna or a short collapsible whip is generally satisfactory for eliminating noises generated around the operating position or in the house, but placed externally usually works better to eliminate noises generated outside the home. Any noise antenna that works, including a combination of horizontal and vertical polarized antennas, is satisfactory, but our technical team can assist you.

The QNC operates as an active antenna by using the noise antenna and the GAIN control to amplify the antenna output. The unit can also be used as a diversity combiner to peak weak signals or null interfering signals.

You can download the complete sheet QNC1-30a Datasheet