QRM GURU – A CASE STUDY Air Conditioner Plant Makes S9 Noise at Home Klaus Illhart VK3IU had a significant noise problem that made HF operations difficult. Klaus has prepared a detailed description of the process of tracing and resolving the source of the interference. Here we have an abbreviated version to give readers a […]
Category: Case Studies
Mitigating Amateur Radio Interference to VDSL2
NBN Co. have recently published a very helpful article on Amateur Radio interference and the NBN. The PDF can be downloaded from the NBN website; click on the image below. You’ll also find plans for a simple 40m notch filter here, thanks to Andrew VK3FS.
Low power wireless charging: friend or foe?
By Ian Jackson, VK3BUF On a recent visit to Aldi, I couldn’t help but notice some new products stacked up in the centre aisle. There was a handheld LED lantern and a wall-mounted emergency lamp. The larger lamp had warm-white and colour-changing modes. The smaller unit plugged into an electrical outlet and activated automatically with […]
The saga of the network switch and 20m QRM
These days, the internet is connected to just about everything electronic in the modern house, from TVs to refrigerators. My family and I are serious internet users, so when the new QTH was being built, I had the electricians run Cat6 cable to 14 outlets throughout the house. I installed a 24 port network IP […]
How’s your noise floor?
By Bob VK3XP I have lived in my present location for over 40 years, and in the early days the noise floor was just detectable. These days it ranges from S3 to S8 to 9. So, how does one go about finding where the noise is coming from? Over the years I have built a […]
QRM to Telstra NBN FTTN modem
This great case study from a VK amateur…. I have a Telstra NBN modem, used for a FTTN service. It is installed on a shelf in the garage My 40m dipole runs across the garage – the end is about 7m away from the modem. Whenever I transmitted, RF would cause the modem to lose […]
Audit your power packs / wall warts
Check your power supplies With the New Year comes New Year Resolutions. The little 5V plug pack that came with the laser show Christmas Present was stamped with a working range of 100 – 240VAC, 50/60 Hz. It will work well in the USA on 110V and even in China where the mean voltage is […]
Radial Free Verticals
Radial Free Verticals By the QRM Guru team From time-to-time we receive emails about QRM and TVI associated with these radial free verticals. The symptoms will usually present as TVI, RF feedback and sometimes an inability to achieve a desirable SWR on the lower bands. We also hear of situations where the antennas appear deaf […]
A BlueRay Player problem
A remarkably interesting fault. By Bob Tait VK3XP Recently I decided to upgrade my UHF TV antenna. Whist connecting the coaxial F connector to the antenna I got a small tingle. I also noticed broadband 50Hz QRM on 40 and 80 metres. Where was this coming from? There were a number of possibilities. I recently […]
Noise Canceller Kit – from VK5TM
With thanks to Phil VK3VB for this case study Early March 2020 saw me working from home due to COVID-19. This led to re-establishment of the long-neglected shack, which was also the home-office. First, the digital modes were re-established with DSTAR, DMR and NXDN along with the standard 2m/70cm FM. Over the past few years, […]