low RFI power converter (not inverter)

[Scott in Michigan]

Has anyone on the Forum ever identified a suitable linear power supply with battery charging circuitry to replace the OEM switching type converter?

I'm an amateur radio operator and am looking for something that is RFI quiet.

Our trailer has a switching power converter rated at 55 amps. It produces RFI about every 20 khz, mainly in the 40 and 20 meter amateur bands.

I'm interested in hearing anyone's success story.

Scott

[bsmith0404]

Not sure if the companies that build converters for rv use even consider that. I’m not even sure anyone would build one for radio use since most I’ve seen are inverters that can be used with battery back up for base stations. Oh the good ol days of Radio Shack having everything you needed.

[ChuckS]

If I knew what brand and model converter you currently have installed I could probably shed some light toward those spurs you are seeing on 14 and 7 meg bands..

I have the stock OEM WFCO 75 amp converter in my fifth wheel that produces no RFI that I have had issues with ..

I often run either a doublet fed with 450 ohm ladder line when space permits or a push up fiberglass pole. 31 feet high with a #14 gauge stranded wire fed inside it.

A UNUn balun is used at feed point to help the load resistance and is then fed with coax and tuner ..

If your converter is an “open chassis “ PCB with heat sink and no external metal housing that will also contribute to the RFI hash you are seeing at various pinpoints across the two bands..

My converter is stand alone separate from the power center fully enclosed.

Also are you running the HF transceiver off 12 volts DC or does it have its own built in PS?

I run a Kenwood TS480 HX off two 45 amp switching power supplies if I have shore power or directly fed off the main coach battery terminals

I also run a Drake TR7 directly off the coach batteries sometimes too.

Anyway.. let m3 know what you have for a converter and what you are using for HF antenna .

Amd of course Imam sure you are aware if using a vertically polorized antenna it will be inherently more susceptible to noise and interference versus a horizontal polarized antenna ..

I’m an “Old School” Ham for over 45 years now.. seen a thing or two with weird RFI issues.

[Scott in Michigan]

Chuck, thanks for the reply. My converter is the same brand, rated at 55 amps. It is a standalone unit located behind the power distribution center, and of course has a closed metal chassis.

Power supply is separate to the radio. My antenna is a MAG Loop located outside the camper on a push-up pole. You may know that magnetic loops have an inherent near-field noise rejection property. However, with the RV parked in our yard at home, I also hear this interference on my home station. In that case I have a multiband Yagi at about 60 ft.

I've already tried various arrangements of ferrite beads as a choke on the AC input line, as well as an Isobar power strip with RFI filtering. No change.

Next I'm going to wind a common mode choke based on mix 31 material on a 4-in core and place that on the DC output line temporarily to see if it helps.

I have a relatively well appointed workbench which includes a VNA so I measure the impedance vs. frequency of any choke I wind.

But back to my main question. Does anyone know of an aftermarket linear power supply/ battery charging system suitable for RV use? Or, a switch mode converter/ charger that is low RFI / EMI?

Scott

[ChuckS]

If you gotta go that far than start looking at medical grade stuff. To my knowledge no typical converter made for RVs is gonna do much better

And I also have a boat load of test gear, scope, etc… I have an 8 element log periodic at the house and with my Rv always plugged in at the house I have not had any RFI from the converter in nine years of owning 5his RV

Maybe you just need to upgrade the converter and go with progressive dynamics unit ..

73

[ChuckS]

AT MY HOUSE THE HF transceiver is an Icom 756 Pro3 and if there were any spurs on any band I would see them on the band scope

My converter stays plugged into the house all year long when we are not out on the road ..

I can even run the receiver preamp at plus 10db with absolutely no RFI hash from the WFCO converter..

[ChuckS]

One other point is perhaps your RFI hash 8s coming from a bad regulator on one of the overhead LED lights in the RV..

I had to rep1ace a few because they were emitting RF has on 18 meg and 3.5 meg as well as 160