The 120 vac inverters draw a LOT of current from the 12 vdc side. The
clamp-on ferrites, especially 31 mix, are likely saturated by the DC
current alone. This renders them ineffective for RF energy. You also need
to treat the 120 vac lines. All these 'beads' should be at the entry point
of the 12 vdc and the exit point of the 120 vac located at the inverter.
I installed a 'True Sinewave' 300-watt inverter in our Airstream. It does
not produce any objectionable RFI. It would even pass the EU
specifications for conducted harmonicds of 60/50 Hz. However, when I pass
a loop of the RG-58 feedline around our solar panel, that couples CM noise
from the charge controller onto the coax and, ultimately, into my Icom
7300. Redressing the coax away from the solar panel (a 80-watt unit from
Camping World) - no loops around the panel - alleviates the interference.
One more point: When the RG-58 simply passes into the camper, on certain
bands, I do 'rattle' the relays in the power distribution of the camper.
Commoning (if you absolutely must: "grounding") the IC-7300 chassis where
the coax cable connects to the radio to the inside metal of the camper,
that ceases. Short, thick (large gauge) wire is necessary for a low-Z
connection. If inside is aluminum, be sure to 'grind' through the
non-conductive aluminum oxide.
Dave - WØLEV
On Mon, Dec 16, 2019 at 6:48 PM <firstname.lastname@example.org> wrote:
> Hello all.
> I have an issue with my HF radio in my 2019 5th wheel camp trailer. I
> have a 100 watt HF radio which I have turned it down to 90 watts out.
> Every time I key up and transmit I hear noise coming from the
> converter. I have flipped all the 110volt ac breakers off and pulled
> all the 12 volt dc fuses out. I still hear the noise. I have put 2 mix
> 31 snap-on beads on the 12 volt dc lines (2 on both) coming from the
> battery to the converter. I put them at the converter. I still hear
> the noise. I am using a screwdriver antenna.
> Any ideas what I need to do to make the converter stop making noise
> when I transmit? The noise sounds like relays clicking.
> Thank you.Rod Rathkc7vqr
> RFI mailing list
*Dave - WØLEV*
*Just Let Darwin Work*
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