Projects, past & present - contd.


- noise cancelling module

I cannot fault this unit, it has made huge improvement in the readability of voice signals on the HF bands. With ever worsening background noise on HF, some bands have become virtually unworkable, at least for voice communication (... do I hear sniggers from the CW crowd!).

I would love to be able to claim that I had some hand in the design and/or implementation of this 'project', but all I did was fit it into an existing speaker housing! All credit goes to BHI Ltd ( for the: NEDSP1062 KBD assembly. Although complete enclosures are available I wanted to use my own enclosure. I already had an extension speaker that I used with the ICOM IC-746, a diecast unit with twin speakers. It is one of a pair bought many years ago for use with a PC - in the days when the sound cards were equipped with audio amplifiers.

The unit operates from a DC supply of 12-18v, the audio input is taken from the rig's external LS socket. There is very little adjustment required, just the audio input & output levels, everything is described in the accompanying booklet.

All of the detail relating to this module is available for download. Product details can be found here.

I did find that the mode setting took a little getting used to. It is done by pressing the mode switch and listening to the number of 'bleeps' emitted (from a small piezo sounder). To change the operating mode, you switch the unit off (one of two press buttons) and while holding down the mode button, turn on the unit again and listen for a sequence of two tone beeps. Finally releasing the mode button when the required beeps are heard.

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