Thanks Roy VK3GB for this somewhat left-field story about interference. Interference, there is always a sign! Some years ago I moved house and as normal spent the first year renovating and redesigning the garden. Why so you long you may ask? I was laying 120 radials ready for my Butternut HF2 vertical. Once erected you […]
Category: Case Studies
Finding power line noise using a VHF AM receiver
Thanks to George Smith G8AOJ and the RSGB. “For several months I had been experiencing random variable level wide-band impulsive noise across the whole 2m band. This manifested itself at times as a strength seven continuous crackling noise.” Read on to see how George traced the offending noise source. This article is copyright of the […]
Eliminate Interference with the MFJ-1026 Noise Canceller
A great demonstration video from Hayden VK7HH and this Noise Cancelling device in a real world scenario. Thanks Hayden.
Finding and killing QRM in the home with ferrite toroids & snap-ons
From Josh KI6NAZ Josh has put together a great Youtube video on reducing RFI in and around the house. Using simple techniques to find the noise source and then using toroids and snap-ons to reduce or illuminate the noise. A very useful video. “For most of us, RFI is around us all the time. It […]
DF Loop kit and noise cancelling techniques
The following case study sourced from Grant VK5GR One thing I have found very helpful for finding sources is to build this kit: https://www.minikits.com.au/electronic-kits/high-frequency/hf-active-antenna/EME234-HF-Active-Loop Click this link to visit minikits website. For the antenna, get some ½” soft copper pipe and form a loop about 30cm diametre and use that in place of the wire […]
LED Lights – Test Results
Some of the most common RF noisy products around the house are LED downlights. We have had reports of banks of LED lights (60+ lights) causing QRM for HF radio at distances of up to 400 metres. Plenty of retailers sell LED lights of various brands, but it is almost impossible to tell if these […]
The best thing you can do to reduce noise in your radio shack
We’ve spoken about the importance of having good house-keeping in your goal for a low noise environment. Other posts on QRM Guru talk about various techniques and tools you can use, but in this video Peter, VK3YE provides a great practical demonstration of how you can reduce noise in your shack. Using Ferrite rings and […]
Tracking down interference in the 2m amateur band
This success story is from Andrew, VK3FS. Thanks Andrew… Whether it’s an annoying buzz or hum, radio interference can certainly diminish enjoyment of our hobby. Finding it and getting it fixed can be one of those challenges that can really try us, but it need not be. This is the story of my local QRM […]
LED Down lights – resolving a significant noise problem
Thanks Steve VK5SFA for this article. Sometime in late July 2019, a strong wideband noise appeared across all HF bands at my home QTH in Adelaide. The noise level was S9+20dB (-50dBm) and was making HF reception from my suburban block almost impossible. I started the process of remedying the situation by logging the interference […]
Noisy fluorescent lights
Here is an example of fluorescent light RFI; thought to be RF quiet, but in reality far from amateur radio friendly. Even though the observed noise on the radio was low, this is an example of “just another” noise source adding to the overall rise in the noise floor. Key words: Fluro lights