HF Noise Mitigation Seminar by W7VO

This seminar is as presented at the August 2021 QSO Today Ham Expo, and is an educational seminar to help both new and experienced amateurs who are on HF and finding themselves plagued with noise. We'll learn what "noise" is, about the various sources of noise, and how to mitigate those noises using a variety of techniques. This will be followed with information on using a low cost SDR and loop antenna to characterize your noise environment.

[@JCO2002]

This is great, thanks. I'm battling noise on my new RTl-SDR V4. I've had the V3 for years, but this one has the up-converter for HF, so much better. My biggest problem is spikes about every 115 KHz from the SPS in the desktop, but think I have a plan to deal with it. Watching this to see if I might. Edit: at 28:00 those faint, repetitive spikes you see are what I've got, although mine are massively worse, and I'm positive it's from the SPS in the desktop. If I plug the dongle into my laptop running SDR++ (I use LInux on both machines), and turn off the desktop, they disappear. I know it's not the 2m USB cable from dongle to computer, because if I disconnect the antenna, no spikes. It's the antenna coax itself where it comes into the house picking it up on the shield, I assume. I've ordered a 6m USB cable that will allow me to get the dongle up on the concrete roof here in Jamaica. Antenna is a sloping dipole about 11m long each side into a 9:1 balun. I get Radio China, Radio Romania, and other distant stations - in Jamaica - quite well every night because the frequencies are between the spikes.

[@herrwingnut]

Please keep doing this 😎

[@pa7rw639]

Thanks for the explaining. Very helpfull.

[@highlandkraftwerks]

Kind of amazed you didn't know the RTL-SDR Blog V3 Will tune down to 500khz.

[@mikeritz9923]

I do, but the version I have only goes down to 28 MHz without a downconverter. I do need to upgrade.

[@JCO2002]

Only with direct sampling, which isn't that great. The V4 has a built-in up converter, but there's a limited supply of them. They're currently in stock, I believe. I had to wait a couple of months from the time I ordered mine on Amazon until I got it. The filtering is much better, too. Quite the nice little unit.