Thursday, December 30, 2021

Further improved antenna in country Victoria and noise fighting

I've continued to work on the 40m dipole here at Drummond and, despite an arm in a sling, managed to throw a line with a rock attached over the branch of a tree and hoist the balun up about 6m above ground. I've also got the dipole to be resonant within the band for a change.

All was going well until a very regular interference pattern appeared across the band. It didn't look like a switch mode power supply as the carriers are quite narrow and didn't drift. Very annoying as some were dead on popular frequencies like 7100kHz.

My first theory was that it was from the micro-inverters in the solar system here. They have a bad reputation and the sun was strong. I isolated the inverters and it stayed. In the end it turned out to be a switching wall power supply for a Synology NAS that I had recently installed. Now the band looks clear:

At 6:30pm local time I had a contact with stations VK2ASU at Maitland and VK2KB at Emu Plains. I could hear them both perfectly but due to the short distance they struggled to hear each other. Here's a video of just tuning around 40m. Hugely different to the experience in the city.

I normally look for good times to talk with John, VK2ASU by watching my WSPR reception of his club station VK2ATZ. Here's a signal to noise plot from the WSPR Watch App. Times are local. (There's a gap when we had our voice contact).

So, very happy with 40m operation now, the next step is more bands and general coverage reception.


Clifford Heath said...

How did you quieten the Synology power supply? Just the usual ferrites etc, or did you have to move it?

Peter Marks said...

Haven't tried to suppress the noise. Synology is currently switched off due to excessive RF noise. I wonder if they care?

Clifford Heath said...

I'll have to put a sniffer loop on the HackRF and have a listen to my one. I haven't noticed any interference and it's in the same corner with the radios.