rf noise generation

[libra]

I had purchased a diversion controller and was surprised at the amount of rf that was on everything. My hf radio, fm, am and even snow on the tv. Even more surprising was when I called the company they offered no assistance and didn;t seem to care.

Ok I returned that one and went to Morningstar. I was reassured before purchasing the tristar 60, and it was installed in the same place as brand x and it worked perfectly.

Now that I am thinking of an inverter, can you hams with experience offer your experience with inverters "that work" I have heard that some brands have problems, and for the amount of $ invested I would like to hear of others sucesses.

Libra

[Flux]

I can't offer you any information as a Ham, but iI have noticed that when powering audio equipment, some do seem much noisier than others. The MSW ones tend to introduce noise via the power supply, which some devices can cope with and some can't ( seems to depend on power supply design). This doesn't surprise me, the thing that does is the fact that some true sine inverters, although they don't seem to bother the power supply, they actually seem to radiate more higher frequency stuff. This is no doubt due to the pwm at low rf frequencies.

Their filtering will be effective at the fundamental frequency and on a scope they look incredibly good. How well the higher rf frequencies are contained depends probably on the interests ( or lack of it from the designers).

I strongly suspect you may need to add some filtering or screening to many of the cheaper inverters. Not like taming a vibrator pack of the valve( tube) era but still a challenge. I find computers are absolutely dreadful at messing up the MW bands but I have seen few complaints. If you work at VHF or higher I am sure the inverter will not be a problem.

Flux

[DanB]

what sort of controller is it that you have problems with?

Im about to install a Trace C40...  I recall our last one messed pretty well with the cell phone we used to have.  I wonder if this will mess with the 2 meter ham radio - if so I might sell it/get the morningstar controller.

[Flux]

RF noise seems inevitable with these pwm controllers switching nominally resistive loads with long connecting leads. Unless they have incorporated suitable filtering I think you will need to add it externally as close to the load terminals as possible.

Many specify a maximum lead length to the dump load, surely this is an admission that filtering is not present or inadequate. Why else would lead length ( as opposed to resistance) matter.

I have no experience of commercial controllers but I suspect that you will only find out from others experience. Sophisticated units with inductors and flywheel recovery diodes should be free from these problems.

Flux

[AbyssUnderground]

I can't say Ive noticed any interference from mine on the 2M band... Everyone's equipment/setup is different though.

[libra]

My problem was with the Xantrex, and the hash was everywhere.

My radios, hf and vhf were on seperate batteries, and the local hydro was seperate for the tv, I don't have an inverter as yet so this had to be radiated.

For the extra and because of the good tech support I am glad I went with the tristar.

All my leads were less than 30" from the batteries to the controller. The diversion to the hotwater tank is teck cable with a metal jacket that is grounded.

Anyway hope that this helps and would like to hear from others.

Libra

[Ungrounded Lightning Rod]

I had a similar problem with a proportional pressure well-motor controller from Goulds Pumps.  Worked great.  But when the motor ran you couldn't use an AM radio in the house or for tens of feet around it.

Turns out they had redesigned it to add noise filtering and recalled all the old ones.  They replaced it (and the associated pump motor!) for free (though I did have to pay the well service guy for the call to swap it).

I hear the dealer who sold it to my prime contractor is no longer an authorized Goulds dealer - which makes me wonder if he had reported it as destroyed and then sold it cheap, expecting that it would never be reported to Goulds.  (That would certainly explain why my contractor claimed it couldn't be fixed and nothing happened until I contacted Goulds personally...)

[Nando]

R.F. Noise is mostly due to the design that allows, via traces and fast rise time waveforms to pollute the air .

To clean some of those R.F Noise Sources is sometimes necessary to encase them in a RF sealed box, because they already built.

Each source needs investigation that sometimes is quite "painful" and lengthy to perform because each case is special to itself.

One may reduce the noise if a ferrite bead is installed in the leads of the gates of the MosFets ( never in the source, this will increase the noise),also,  investigation to see how the gate is driven to insure non transitional RF oscillations in the MosFets.

MosFets when paired in parallel with common gate connections and some inductance in the sources can oscillate up to about 500 Mhz during the ON/OFF transitions when the MosFet is "traveling" in the linear region and the miller effect is keeping the gate more or less clamped ON for some nanoseconds.

Traces are good RF emitters.

This could become a BOOK if I keep talking about this problem, one of my Engineering disciplines in my career.

Nando

[Hilltopgrange]

GE OM SRI FER UR QRM = QRA MI0CGV RUSSELL

I will continue in plain english I think.. its a long time since I used any of the above lol

Have you checked your rf earths from and to your rigs etc?

I had a similar problem a few years ago with an ft1000mp I had just bought and it nearly drove me nuts lol. To cut a long story short the cure was to connect a seperate rf ground rail to the shack ie 15mm copper bar with heavy straps to each rigs ground lug, the bar gets connected to 4 or more earth rods outside in damp ground via heavy earth cables, the heavier the better.

I didnt see your call so I dont know where you are! if you are in the States check out the ARRL handbook or in the UK RSGB radio comms handbook for a better discription

If you are sure of the source of noise, cage it in a faraday cage/screen and ground it.

I hope this is of some help as I know how frustrating it can be, at one point I was only able to work CW it was that bad. The above fixed it for me!

73 DE MI0CGV

[alancorey]

I think it's a problem that's common because most people don't notice it exists.  I've got 2 cheap little (140W and 400W) MSW inverters and they both cause trouble.  They'll lock up my radio scanner on both high and low VHF bands.  I haven't tried HF with them running.

Most people just don't listen to radio anymore, at least not at lower frequencies.  I enjoy listening to 80 and 160 meter AM ham bands, but I'm an odd duck.  I've lived places that using a tuned shielded loop antenna was the only way to hear anything.  On my new-to-me little 6 acre place with few neighbors and no grid connection, I can actually listen to longwave if I feel like it.  I'm far enough from light dimmers and automatic night lights and other things that slice up sine waves that it's pretty quiet.  Most people wouldn't appreciate that, but I plan to keep it that way.  Television sets are awful with their 15 KHZ sawtooth wave that gets into everything.

Anyway I think you have to check everything you buy, and either return it or find a way to contain the noise if it needs it.  The best place to stop noise is at its source, so I think each time you get something new that might cause a problem you need to spend time listening to your favorite radio bands while there's still time to return it.

There are resources where you can read about reducing RFI, the ARRL Radio Amateur's Handbook used to have a fairly good section.  Shielding, bypass capacitors, and ferrite toroids around connecting wires are some tricks you can use.  The most powerful though is to return the device and complain loudly.  That might also benefit someone else.

  Alan

[libra]

Well this new controller seems to make all the difference. I run a 817 qrp and an 890 all off seperate batteries and haven't had to do anything.

I have seen the article about grounding the rigs in the hnadbook but have been lucky.

My feedlines are hardline that run underground out to the tower and then I use open line to the antennas.

I guess as someone said I'll have to try inverters out but they have to be brought in and it gets difficult to return used equipment.

I am located in nw ontario and the top corner of Lake Superior or just outside of it place called Kakabeka Falls.

Still trying to get rid of the pencil for my cw  (amother goal)

73  ve3axl

[Nothing40]

Here's a handy link I just ran across the other day.

http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf

[la7qz]

Hi

I have three different ways of powering the computer on my boat:

1: A Vanson SDR-70W 12V power supply with multiple output voltages. Mine is set to 19V for the Packard Bell notebook.

 The Vanson is the most economic way of powering the computer, but puts some hiss on the HF radio (IC-718) which interferes with weak signals. It does not interfere with the boat's audio system when I use the MP3 player (Neo Car Jukebox) as an audio source, but when I plug the boat's sound system into the headphone socket of the computer (for audio when I watch a movie), this puts a loud high frequency hum on the speakers. The volume varies with the volume setting of the sound system, but is constant with the volume setting of the computer. It is considerably damped by switching off the screen. (but then I can't see the movie...)

2: A Xantrex 150W 230V Inverter driving the original power supply.

 The Xantrex puts a loud hiss on the HF radio, but does not interfere with the audio system in any way.

3: An ancient Tripp Lite 400W 110V inverter driving the original power supply.

 The Tripp Lite hums audibly. It does not interfere in any way with the HF radio. It puts a loud 60 Hz hum on the audio system even when amplifier is not connected to the computer.

So, I find myself using the Vanson most of the time, except when I want to watch a movie or am working DX on the HF radio, The Xantrex for watching movies (with the HF radio switched off) and the Tripp Lite when using the computer for navigation when I naturally want the HF radio to be functional.

This is driving me nuts! I have tried ferrites, but maybe not enough, as they are difficult to find out here. Hopefully it will be easier to find stuff when I get to St. Maarten.

Regards,

Owen Morgan, LA7QZ/MM

Yacht Magic

Falmouth Harbour, Antigua

[libra]

Wow   all the hoops that a guy has to go through to get things to work.

I was at a hamfest on the weekend and found a bag of toroids and snap chokes and picked them up on speculation.

Also watch for large bypass caps.

I also found a buzz in my fuse box when the tristar was diverting but not in the controller itself.

I tore the fuse panel apart and concerned about a bad fuse and finally found that it was the ups I was using.

I can live with that but feel better knowing what it is and isn't

libra