I'm on our annual family vacation to the Carolina coast for the week -- heading back to the Charlotte area on Saturday May 28. It's been exactly what we needed -- three generations doing what relaxes them most. Good food and conversation, walks on the beach, bike rides, a visit to the NC Aquarium, a little golf, and a little radio time for me!
This year, we're in a home about a block from the Atlantic Ocean. Like many homes around here, the "main" house is built on stilts (this area is known as Hurricane Alley -- earning that reputation in the 1950's with storms like Hazel) -- and it has a number of porches which are perfect for antennas. I opted for an end fed 41' wire fed through a 9:1 UnUn along with about 30' of counterpoise; the main radiator slopes down at about a 45 degree angle to an empty lot next door. The KX3 is connected to the feedpoint with only 4' of RF-400 coax -- and I'm powering the setup via a rechargeable 12v DC supply (by Bioenno).
Results have been encouraging, with "you're only running 10 watts?" being a common phrase in QSOs. I've learned over the years that if you can power your rig with a battery, and minimize the length of the feedline (in particular with non-resonant / and or unbalanced antennas that require a tuner), the receive noise level will be significantly reduced. The rise in switching power supply noise and the like is very prevalent in many of the places we stay on vacation...with the rental properties filled to the brim with the latest Chinese made gadgets all having inadequate filtering. Getting the antenna as far away from the noise sources, minimizing feedline pickup via choke filters and/or a small length of coax, and decoupling from the AC mains as much as possible have yielded far better noise floor performance.
I experimented with placing additional ferrite (mix 31) on the leads of my KX3 AC power supply yesterday. The DC lead comes shipped from the factory with a single ferrite cylinder of unknown mix. (The power supply is found here: https://proaudioeng.com/products/pae-kx33-low-rfi-ac-power-supply/) The purpose was to explore the receive floor differences between using it and a battery alone. In my experience, this ProAudio PS is very quiet -- however it can serve as a noise path from the AC mains into your setup. I watched the noise floor drop, significantly (about 2 S units), as I added a single snap on core to the AC power cord; there's no proof like direct observation! Of course -- switching completely to battery power dropped it even further. [There's a video online of this same effect -- you can hear the difference: https://proaudioeng.com/common-mode-cm-currents/ ] When I get back to the shop at home, I'll be permanently adding a few more ferrites to this switching mode power supply.
