Help with HF RFI

[Vic]

Hi Justin,

Thanks for the info,   and pic.

YES,   sorry for the mistake on  how your radio is powered.   12 V radios do not usually do well,  connected to a 24 V battery.

Your cables and core look fine.

It is probably not worth it to try getting some more turns through that core.

Did refer that other Thread of Tobit's,   and do not know how much isolation you tried,   but,   when you disconnect the antenna from the radio,   does all of the RFI cease?

Do you think that adding the toroid with the PV and batt cables through it diminished the RFI at all?

The level of the RFI should vary,   based on how much power the CC is producing.

Am quite distracted,   finishing income TAXes,   and  paying,   so more later.   Thanks,   Vic

[boB]

Well, those results suck.

Next I think is to remove the Classic from its mount and see if its chassis grounding is part of this issue.

I do not know how the Classic is mounted.  Maybe a picture of that ?

[justinbowser]

Bob, classic is just screwed to the wall with a ground wire to the breaker box which is grounded to external ground rod.  Sorry about the huge pics but I am at our cabin and Photoshop is on my home PC so I have nothing to resize them with...

Should I put in a ground rod for the panels?

[Vic]

Hi Justin,    Thanks for the pic.

It is a good idea to connect all of the metal enclosures together with a grounding wire (Eauipment Grounding Conductor - EGC),   this is mostly for personnel safety.

Would suggest doing the same with the PV module frames.   Typically,   this cable  is NOT brought inside structures,  buy would connect to your Ground Electrode/s.  There are specialized clamps for this.  Some of the PV frame grounding is for personnel safety,   and some to try to protect connected electronics/electricals,   from nearby lightning strikes.

Is there a ground conductor in the AC cable twix the breaker panel and the inverter?  Does this ground connect to the inverter case?

It seems that if adding the toroid did any good,   that  is was only a slight improvement,  which is surprising.

Is the battery negative connected to your ground?

We have used metal conduit (EMT) for all cable runs that are above ground,   including control  and communication,   BTS,  etc.

We are going to make some changes to our RFI suppression gear,   soon.   This should be a  interesting.   Will be using several of those "monster" toroids.

Later,   Vic

[boB]

Thanks for the pic.

Did you turn the inverter OFF also when measuring the RFI ?

Did you remove the antenna connector from the radio to see if it still receives controller noise ?


Some ideas.......

Try disconnecting the green ground wire from the Classic.

Move those wires away from the inverter.

Twist the cables together.

Run the PV through metal grounded metal conduit.

Run the battery cable from controller through  metal conduit.

Try running the radio off of a second small 12V battery that is disconnected from the big battery and see if the noise level comes down.
Disconnect the ground to the radio if it has it.   Add a small ferrite around the radio +/- power lines.

Add a metal plate behind the controller and inverter that are grounded together.

You can try grounding the PV frames but that may not do anything.  But it might !


I will think of more stuff....   Lots of things to try.

[justinbowser]

Vic,

I have Romex w/ground between inverter and panel.  I will check with a meter tomorrow to see if inverter case is tied to ground and if not I will do that.  I will also physically ground the battery negative to the ground point in the breaker panel, didn't really see a need for that since I "assumed" battery negative would be grounded through all of the stuff hooked up to the bank!

Next trip to "The Power Store" I will pick up the grounding hardware for the racks and ground them to the same ground rod the cabin is hooked to.

I have ordered a couple of smaller mix 31 toroids and will put one on the DC leads running to the refrigerator and one on the DC input to the radio.  It probably doesn't help that my radio is probably almost 40 years old and technology has came a long way since then.

I also have to find some LED bulbs that don't produce RF "hash" as during the day with the refrigerator, lights, and Classic breathing hard I have a +20 noise level!  Without the lights on I have about an S7 level with the 'fridge and Classic only seeming to produce RFI on specific frequencies.  But, at those FX it is very strong.  If I have time tomorrow I'll try to record the noise the Classic is producing tomorrow and attach it to this thread.

73,

[boB]

Good deal Justin.

The grounding of the negative battery leg will be interesting.  Can't assume everything grounds it but I can certainly understand why it might.  Capacitors connecting everything to everything.   Well, sometimes.

I don't know if newer technology radios are any better because RF is RF and it gets into stuff.  I can't do much here at my house because of all the neighborhood noise as I think I mentioned before...  Today I tried connecting back up my vertical in the back yard thinking that I remember it worked OK 20 years ago.  But, doesn't seem to be any lower noise and W1AW code practice on 40 meters sounded exactly the same on single wire antenna or the vertical.  I thought that the noise came down slightly when I moved the horizontal wire antenna (offset feed dipole) over about 40 degrees but now I'm not so sure it is much, if any better.  I can hear strong signals though through the S9 background noise on HF.

[justinbowser]

OK, had a chance to play a little between Honey-Dos.  Strange that I still have a pretty good Honey-Do list even out in the wilderness, but I digress...

With the inverter turned off and the 'fridge not running I have a background noise level of about S7-S8 on 40M which in my case being a mile from the nearest neighbor and power line seems a bit high.  When I tune (on 40M) to one of the "hetrodynes" put out by the Classic it is about +20.  If I disconnect the antenna I can still hear it but there is no meter indication.  I would guess that means the noise I am getting is radiated?

If I ground the negative battery bus bar the noise actually sounds stronger!

I recorded a couple of audio clips of the noise.  One on 40M and the other on 20M.  The noise on 20M is not as strong as on 40M but still pronounced and repeats at regular freq. intervals.  The CC output during the recordings was about 30 A as it is slightly overcast right now.

[ClassicCrazy]

I think you said you are using a dipole antenna ?
I made a loop antenna and it helped with  noise .

Larry

[boB]

Ouch !   That is AWFUL !!

Oh man.  So, has this Classic always radiated this badly ?

Are there any wires coming out besides the power lines ?    Battery temperature sensor or maybe Ethernet cable ?

[justinbowser]

Bob -  No it hasn't.  I had not been on much in the past month and during that period of down-time I took down the MFJ-2240 portable dipole I had up about 25' and in it's place stuck up a 40/20 fan dipole with the apex at 35'.  It's a homebrew job using an MFJ 1:1 balun at the top and fed with RG6x.

Your mention of ethernet made me remember that during that time period Larry was helping me out with trying to monitor the Classic (it's a 200SL) and I have a cable coming out attached to a serial I/O board feeding a WIFI module.  Could this little cable be the cause of my grief?  I will disconnect it and see what happens.

I might use the two FT240-31 toroids I have ordered to make a common-mode choke at the receiver end of the coax instead of the DC conductores to radio and 'fridge as I had originally planned.  This may have to wait for a few weeks as I will be going back to "civilization" this weekend to catch up on a couple weeks worth of work that has been stacking up while I have been in the mountains hiding out from the bug.

Larry - I currently have a 2 band inverted Vee

[justinbowser]

I removed the cable for the wifi adapter with no change.

[justinbowser]

Oh, also a WBJr wire...

[Vic]

Hi Justin,

YES  that is very loud RFI  !!

Isolating the antennas from the PVs,  power room,   and cables that connect to them is quite often  a large help.   If you could possibly move your aerial one hundred,  or more feet from the PVs,   power room and AC cables  it might be a win for you.

The CM choke on the coax cable at your radio is a good next step.

Am certain that this is conducted RF energy that is radiated from connected cables.   t is surprising that your monster CM Choke appears to have done nothing,   at all.

Good Luck,  73,   Vic

[boB]

Temporarily remove the WB Jr. wire just to make sure.

Actually, I heard some sort of periodic sound in that recording you uploaded.  Could have been the 10 Hz from the WB Jr. !!

boB