Why?
You probably came here because you already know that the stock Victron MMPT Solar Charge Controller is nearly unusable if you need a quiet RF environment. I first noticed problems after installing solar on my sailing yacht. While the sun was shining hard on the solar panel (it's only a 100W :) ) the VHF reception went bad and the AIS reception range dropped.
Problems are worse when we talk about shortwave. And thats what I am doing right now: I want to power my KiwiSDR with this thing. The first run was really disappointing. Noise from the Victron everywhere.
What to do?
I did a quick google and didn't find a solution. So I had to play around with a few coils and capacitors. I probably should provide you with screenshots from the spectrum analyzer but this time I am A) too lazy and B) had a realtime look on the Kiwi spectrum to confirm my experiments. This is what works for me (and it's no professional solution at all - less math was involved, just plug - play - compare)
That's my 100/15 here.
I added some common mode chokes to all inputs/outputs.
There is also a nice amount of differential mode noise coming from the "load" output. Most of that noise showed up between 24MHz up to 30MHz
Please ignore the microcontroller on the left side. That thing just picks up the serial data from the controller and pushes them to my Wifi.
THIS IS ONLY A TEST SETUP - NOT THE WAY I DO ELECTRICAL INSTALLS! - just in case :-)
From left to right:
- Battery Connector: 10mH, Imax 5A (enough for my panel)
- PV Connector: 3.3mH, Imax=4A
- Load output: 10mH, Imax=1A, C=0,15 in parallel
- Load line 6 times through FT140-43 style ferrite
The coils provide enough current for my use case. Feel free to take stronger coils. I took them from a sample box (Würth) but the could of cause be wound DIY.
The KiwiSDR is now running 24/7 on solar. If you check in on the Kiwi, you may still notice some noise but thats from the neighborhood and I am afraid I can't do anything against that.
