Help with HF RFI

[Vic]

Hi Justin,

Thanks for the pics.

Much of the ringing,  is probably due to scope probe grounding issues.

The ground leads  on the probes  need to  be short,  and direct to the PV and battery terminals of the Classic.    This can be difficult to do.  You might be  able to shut off the PV and battery breakers of the Classic,  and add a bare ground lead to either the unused Classic ground at the blue terminals,  or loosen one of these  blue ground terminals,  and add your scope probe ground to one of the two Cl grounds and retighten it well.

If you have Common Mode chokes on the PV and/or the battery leads,  you would want to also look at the far side of these chokes,  to see what is being conducted on the cables that connect to these chokes.

Am in transit today.  Others will have more meaningful comments.

Thanks,  later,   73   Vic

[boB]

Vic may be right...  But there is an easy way to see if all your is seeing is real or if some or most of it might be due to common mode noise.

Connect the probe's tip and ground together and then touch that combination to where you had the ground in your pictures.

If you see no noise on your scope, then what you were seeing was real differential noise.

I have to do this all the time in the lab.

Sometimes, running the scope probe cable through a ferrite a couple/few times can reduce the CM noise seen.

[justinbowser]

After reading Vic's reply I did a little experiment.  The waveforms I posted were between the "choke" and PV array with probe ground hooked to the metal conduit.  I measured at the attachment point inside the CC and the ringing was gone.  Poking into the cable on the other side of the "choke" showed the noise was back.  The "choke" is what I mentioned earlier in the thread which was just two turns through a mix 31 toroid.  I went ahead and removed the toroid but the conduit ground is still noisy.

Now to Bob's test - I clipped the scope ground to probe tip and then touched this to the conduit and just a flat line.  I hooked probe ground to ground wire coming from ground rod and touched probe tip to conduit and tons of noise.  So, I guess there's not a bunch of noise radiating out from the panels. 

I guess I'm back to square one!  Next spring/summer I will maybe move the antenna farther from the panels and orient it N-S instead of E-W and see what happens. 

[justinbowser]

Slight update here...  I finally gave up on trying to squelch all of the RFI I have been plagued with and moved my antenna further away from the cabin.  This appears to have all but eliminated the RFI from my inverter but the Classic's "birdies" remained.  I bought a West Mountain Radio CLRdsp and am able to filter out the birdies so I can at least now operate.

I have recently put together a uBITX V6 QRP transceiver and so far have made 74 contacts from the cabin in a little over a month!  If MidNite ever makes a newer CC that is a bit quieter on the HF bands I might be convinced to buy one.  Other than that the Classic 200SL has performed flawlessly.

Quick question - Is "Chatty Cathy's" voice an off-the-shelf produce or does she work for MS?  Just curious...   

[ClassicCrazy]

Have you heard her calling CQ yet ?

Larry

[boB]

Chatty Cathy who can be silenced if you want, came from MidNite Solar.  She was a gal that actually worked for us who did the voice.

The Spanish version that will eventually be coming is also a gal who works for us still.

So, you DID try adding ferrites to all 3 (common negative) or 4 wires coming into the Classic wiring compartment ?  Hard to remember. I suppose I could read the whole thread LOL

73

[justinbowser]

Bob - Thanks, I was just curious since my wife and I kinda think of her as part of the family, now!

Yeah, tried ferrites, etc., so I kind of gave up.  Had to put antenna back up anyway since a storm snapped the mast I had it hanging from and I got a good deal on the CLRdsp off QRZ classifieds so all is good.

73,

Justin B.
KI5GKD