Radio interference , any advice ??

Submitted: Thursday, May 19, 2016 at 16:45
ThreadID: 132459 Views:3205 Replies:6 FollowUps:6
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I have fitted 2 x 80 w solar panels to the roof of a 100 series 4.2 turbo diesal...panels work well but cause interference on any am chanel on the cars radio..(but no interference on fm ) dose not seem to effect an 80 channel uhf or barrett 950 hf that are also installed...have had the same units in three other 4wd previously , same interference in all...
Can anyone advise if this can be fixed and what is required ?

Thankyou for any suggestions.
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Reply By: Baz - The Landy - Thursday, May 19, 2016 at 16:57

Thursday, May 19, 2016 at 16:57
Can't help, but interested in the response as I feel my panels interfere with my 80 Channel UHF.

Cheers, Baz - The Landy
AnswerID: 600304

Follow Up By: Tim F3 - Thursday, May 19, 2016 at 17:02

Thursday, May 19, 2016 at 17:02
Thankyou for the reply . Do you get interferance on am radio ??
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Follow Up By: Baz - The Landy - Thursday, May 19, 2016 at 19:28

Thursday, May 19, 2016 at 19:28
No, only seems to be UHF...

Cheers, Baz
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Reply By: Member - Chooky and Wobble - Thursday, May 19, 2016 at 17:44

Thursday, May 19, 2016 at 17:44
It will be the regulator. The new ones pulse and the rate at which they pulse causes radio interference. This has been a long term problem at mountain top radio installations. If your lucky your regulator can be set to have a fixed slow pulse and it will just give an occassional click on the radio. Check the handbook for the regulator. For best charging the fast variable rate is best so when not listening to the radio you can set it back. The other problem is that some of the regulators can cause the float level to rise above the safe working voltage of some radios.

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Follow Up By: Tim F3 - Thursday, May 19, 2016 at 19:32

Thursday, May 19, 2016 at 19:32
I have a cheap mppt regulator nothing to adjust or alter that i can see. Thankyou for your imput.
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Reply By: Rangiephil - Thursday, May 19, 2016 at 19:59

Thursday, May 19, 2016 at 19:59
I was told by an "expert" that one of the things that cause interference with home Solar installations is that the feed in cable to the regulator should be in twisted pair configuration as this cuts down the RF interference.

I just wish that all the ones around my house had done that as I cannot listen to AM any more in my street.
It may be the same for a car installation so it would probably not hurt to put your wire in a drill and let her rip.
Regards Philip A
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Reply By: allblack55 - Thursday, May 19, 2016 at 20:32

Thursday, May 19, 2016 at 20:32
I had exactly same problem Tim, but because my panel capacity was less than the load I was able to remove the regulator and solve the problem without fear of overcharging the batteries, probably not a solution for you. RFI shielding and suppression is not an easy task. An option if you wish to retain some form of regulation is to steer clear of MPT or PWM regs and find a linear regulator, cheap and not very efficient compared to the former, all depends how keen you are to hear AM stations, but then life is full of compromises .Is also possible that some regulators do not cause interference, it`s called 'Chinese choice'.

AnswerID: 600314

Reply By: Malcom M - Friday, May 20, 2016 at 06:36

Friday, May 20, 2016 at 06:36
It will be the MMPT regulator. Any solution is going to cost you, either replace the regulator or modify the system.

To modify things, you need some large ferrite rings which you can salvage from old computer power supplies - the rings will look like these
have to be big enough to wrap a few turns of the power cables into like this -
Preferably both the +ve and -ve should be wrapped in together but, depending on your cabling, that may require a huge ferrite. Splitting the + & - between 2 rings is likely ok just not as good.
Something like 4 or 5 turns should suffice with the ferrite located close to the regulator. The idea is that the ferrite chokes off the spike energy before it can be transmitted via the battery cabling. Some of this is transferred through the power cable to the target but a lot is radiated by radio waves so will be getting into other peoples gear as well.

If you have any of this style ferrite lying around - then you can clip them onto the battery leads closer to the vehicle. These are often supplied with computer monitors and often just clip on.

If you still have the noise then surgery is required and you need include some small capacitors. Small 100pf units should do and simply connect between the + & - wires. You want one at the output of the regulator plus maybe an additional one at the affected radios as close to the radio as possible (might have to cut the wires to fit). They will have little effect if placed down the power cables away from the units.

That should have killed it off but there's no guarantees with RF. It can take a lot of trial and error but teh above is pretty simple to try out.

AnswerID: 600326

Follow Up By: Bob Y. - Qld - Friday, May 20, 2016 at 07:03

Friday, May 20, 2016 at 07:03
Jaycar have a couple of ferrite clamp-on fittings, as well as ferrite rings.


Seen it all, Done it all.
Can't remember most of it.

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Follow Up By: HKB Electronics - Friday, May 20, 2016 at 09:43

Friday, May 20, 2016 at 09:43
Fit the ferrite rings as close as possible to the charger, if that doesn't work you could also try wrapping the regulator temporarily in some aluminium foil and grounding it being careful not to short any terminals and only do this for a short time to determine if it is effective else the regulator might overheat. I fit works them
mounting the regulator in a vented metal box might be the go.

Personally I'd get a better regulator but check with the supplier before purchasing another unit that it has effective RFI suppression built in.

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Follow Up By: Echucan Bob - Friday, May 20, 2016 at 09:52

Friday, May 20, 2016 at 09:52

I am guessing this is the same concept as the tin foil that I wear inside my hat (to reduce RF mediated thought insertion), and pioneered by Faraday (the Faraday cage)

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Reply By: Tim F3 - Friday, May 20, 2016 at 08:18

Friday, May 20, 2016 at 08:18
Thankyou for the replies , have tried 2 x small clip on ferrites

No change but will try the larger ferrite rings you suggest.
AnswerID: 600331

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