QRM Loop Antenna

QRM RF Loop Antenna for detecting

AT the monthly club meeting following on from the WIA presentation a month or so back, Ian and Chris from RASA recently gave an interesting and informative talk to members where some great resources and information around interference hunting on the QRM.Guru Website and kindly donated a QRM antenna kit to the club.

If you have an interference problem, the tips will help you document and evidence the issue and that will make the job of enforcement by ACMA easier in a time of increasing pressures on their capacity to undertake investigations. Anecdotally, with the right details recorded and provided, action can be quite quick.

The kit is a useful resource for finding and eliminating RF interference around your home.

Thanks to David VK3RU who has built the kit in quick time, this kit is now available for loan by EMDRC club members via our library.

David said ‘It’s a simple project to build too – a 900mm diameter loop, at the centre point (450mm a side) braid cut back 10mm on each side. Adding that it is terminated centre-and-braid one end, braid only the alternate end. In my case the red band denotes the braid only end.’ ‘I built my own version for a start to familiarise the construction.  Both work well and now I have finally solved my own QRM source here at home. … and no, I will not be admitting that source into the public domain!’

David also mentioned that if you search for ‘qrm.guru’ you will find the RASA website or https://qrm.guru/how-to-locate-the-noise-source-building-df-loop/  There is also a YouTube on how to make it.

Dave VK3FDRS also constructed a version to familiarise the construction and sent in a couple of photos – it’s ready to go. Dave reports that it works well and now to find his QRM source at home. The  ‘T’ square was added to stabilise the loop as it had a tendency to flop over. 

Great stuff and thanks to both who have provided some details and photos to share with members. Nice work!

As a PS, Peter Parker commented via FB ‘While it won’t be as sensitive as a commercial receiver, this all band receiver is quite good for sniffing RF. I built the LM386 version – worked first time. Can hear modems, switch mode supplies etc. Picks up 3MP with 1m wire. http://www.techlib.com/electronics/allband.htm

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Regards Ed.