I have been using the DC-DC to power my amateur radio. Occasionally when I transmit (usually when autotuning higher VSWR) the converter will output a significant over-voltage. The radio senses >16V and shuts off. I suspect that RF is getting into the DC-DC unit and causing deregulation. The radio uses the HF bands (1.6MHz through 30MHz). I did not expect highly rated converters like Victron to be succeptible to RFI.
I have yet to try 0.1uF or 0.01uF caps on the input/output or ferrite. I figured I would ask here before I started shotgunning a solution.
Occasionally when I transmit (usually when autotuning higher VSWR) the converter will output a significant over-voltage.
That would make sense as there is more reflected power, quite often it’s a harmonic that causes problems, first off it would measure the RF to confirm your suspicions.
I did not expect highly rated converters like Victron to be succeptible to RFI.
All equipment is tested to a set standard (including Victron’s) but that will be a set power @ at set distance ect under all relevant conditions, and it might be you’re exceeding what the equipment can be expected to reject.
Sometimes just moving something a bit can fix the problem (or a small amount of filtering) other times screening parts of a PCB or equipment is what you have to do.
Come back once you have done this and let us know.
[kk1l] Yes I agree a mismatch will increase the current or voltage and the field. Also agree it is probably a harmonic, since most choppers are running in the KHz rather than MHz. Measuring the RF at the DC-DC unit is not so easy. But based on the issue happening when tuning would support RF as the cause. I have tried to replicate the issue on my workbench where I might make measurements and try solutions. The issue has repeated on three different setups in different locations, so I am disappointed I cannot get it to happen in a controlled environment.
[kk1l] I have tried varying the location of the unit and how wires are run…right angle crossings rather than parallel for example and making sure the unit is away from radiation sources. I added 0.01 ceramic disc caps to the IN and OUT ports and will see how that works when I am next in the field. I suspect there are already caps like this on these in the unit already, but it cannot hurt to try.
Out of curiosity: with how many Watts are you autotuning and to what type of antenna ?
My TRX’s all autotune with 5 to 10W to the antenna.
Are your powering your TRX straight from the Orion (with only 9A at 12V that would seem weird) or is there a battery in between ?
I’d expect more trouble from normal TX’ing at high power than when autotuning.
You would have significant VSWR or high common mode currents and RFI (due to bad antenna ground ?) in order to cause deregulation in an Orion, as they’re pretty well shielded.
An RF Choke or common mode filter could help. A Zener on the Orion output as well.
If there’s a battery inbetween the Orion and the TRX, I’d expect that one to ‘eat up’ the high voltage spikes. You could also wire the TX or Tune contact to a relay that turns off the Orion so you’re running on battery while TX’ing and the battery gets recharged when RXing.
I’d try to lower the source of the RFI first.
As for myself, I’ve used an MFJ Battery Booster and never had any issues with that one.
This situation occurs while in the field. I have had the issue at each of the POTA activations. The setup is generally the same, but slightly different antenna placement & height.
Elecraft KX2 running 3W (has shutdown action when DC input voltage is >16V)
Hardrock-50 amp (approx 50W with 3W drive)
120’ dipole fed with open wire ladder (600Ohm) up 30’ to 60’
1kOhm choke shield choke from amp to 4:1 current balun
There is about 15’ of 10ga to the input of the Orion from 200Ah of LiFePo4.
I had zeroed in on the Orion because when I use either the internal battery of my KX2 or direct from the battery (input to Orion) the rig does not overvoltage. When it happens it happens quickly. There is a “error >16V” on the KX2 display and then it powers off. This does not 100% mean this is RFI to the Orion. I have added 0.01uF caps on both ports and will see what happens.
Treat your installation as a mobile installation. I suggest reading everything you can by Jim Brown K9YC and K0BG. Search the web for how to eliminate RF for mobile ham radio’s.
Many problems go away with the application of several turns of wire around Fair-Rite #31 big clamp on ferrite cores from reputable dealers. Wrap both positive and negative leads, antenna, and computer cables. Try moving them around is different locations.
It is possible that RF is getting into your BMS, so try a big #31 ferrite close to the BMS.
Michael
KB0EW
Thanks for the references. I am familiar with K9YC and his “pin 1” treatise. Keeping most of that in my hip pocket so to speak. I may have found my root cause in a loose shield connection on one of the coax I was using. We’ll have to see with my next portable operation…might be some months.
