I'm installing Outback MX60 controllers at remote mountaintop VHF comm sites, and have suddenly run into interference problems. About 10 installs thus far, and the last 3 have varying levels of interference on the VHF radios when the Outbacks are operating.
These radios are normally tuned to the marine distress freq.- 156.8MHz, and this is the frequency that noises up. Other marine band frequencies are usually clean, but do occasionally noise up as well (I suspect when charging is at it's peak)
The controllers are about 5 feet from the radios, and I am pretty confident that increasing this distance would resolve the problem, but would prefer a quicker/cheaper fix. I was wondering if anyone here has experienced anything similar, and if so, has anyone attempted a faraday cage screen around the controllers as a solution?

More tidbits for those who will want to know-
24v battery
radios are 24v
pos gnd
controller cases are grounded
radios and everything else onsite grounded
2 controllers per site
24 Solarex 60W panels on each controller
panels wired 48v

The MX60 is not Class A or B FCC certified

The New Xantrex WX-MPPT60-150 is and would most likely resolve your interferance issues.

As for trying to field make an MX60 better emissions wise, thats a tall order as the noise will radiate out any wires comming from the MX60, PV/Battery wires for example

that's quite far up in frequency to be getting interference and i'm surprised the interference made it up there that far. how bad is the interference?
i could suggest in the meantime to try placing ceramic capacitors (.5uf or higher and the caps can be added together as each is paralleled to equal that value) inside across the output of the controller in hopes of shorting out some of the radio energy being emitted before it can be radiated by the wire to the batteries. the capacitors will short out only ac and will not short out the dc btw, but other than the caps you have 2 options. 1> see if outback has an answer for this or 2> get, as guppy said, the xw controller. let us know of the progress/result of any efforts you try if you would please.

Thanks guys. I must say, I was surprised the MX60 was not FCC cert'd.
Just got my Outback forum confirmation so will ask there, but going to the Xantrex isn't really an option. All the Outbacks were purchased by my customer some time ago, so we will make them work.
It's helicopter access, so when we go, we'll go loaded for bear. I will try caps near the controller and rerouting cables, but if we have to, we will relocate.
There are actually two buildings on each mountain, a radio hut and a generator/battery hut. Mounting the controllers in the gen hut to begin with would have been a much cleaner install, but we are working with the existing infrastructure. The original design was just the radio hut, with batteries in it, and TEGs mounted inside the solar panel frame to supplement the PV.
When generator huts were added, batteries were moved there, but solar still came to a controller in the radio hut, then over to the batteries. Looking to keep cost down, customer wanted us to just replace the existing controllers. Moving them to the generator hut will require new runs from the panels at most sites as the generator hut is further from the panels than the radio hut.

Niel,
I didn't answer your question. the noise level varies from site to site. At about 7 sites, no noise whatsover. In fact, one site has had Outbacks for 2 years without complaint. At 2 sites, the noise seems to only show up when solar is really cranking. At one site, it's constant and bad enough that the radio is not useable. Normal marine traffic in the area is drowned out by the noise.

if you have ferrite cores available, you may wish to place them over the output cables of the mx60, but most of those are used for power frequencies up to the am broadcast frequencies. you are way above that, but it couldn't hurt to try though. don't overlook the possibility of interference radiating from the pv input side of the controller as well and determining that you could do with a handy talkie or possibly a field strength meter around the input cables. do also check for a proper ground and be certain there are not any ground loops. an obvious one would be to switch radios from the bad site with a known good site to see if the radio has something to do with it, but you can do this with the controllers as well to see if it is the controllers doing it. if i'm going above your knowledge on any of this please state so.
you have thermals on the pvs? please elaborate on that for me as you've peaked my interest. for the record i know what they are, but haven't heard of anybody putting them to pv frames.

The TEGs were taken out when the generators went in. The frame that the solar panels are mounted on just acted as a mounting spot/partial shelter for the TEGs. They used them for quite a few years, but they needed rebuilt every year or two, never started remotely with any reliability, and were very inefficient compared to the internal combustion engine generators which are "on demand".

Radios have ferrite cores on their power leads within inches of the chassis. I am going to put together a bench test with just a couple solar panels and take a look at what's on the input/output leads, try some capacitors.

very good ak. i assume you did contact outback and what did they basically say to you? i do want to know this as i'm sure others do as well. as to your pvs up there, how do you have them mounted and aimed. near arctic circle can be problematic for pv power during winter, but summer would be problematic too with the sun going 360 degrees or nearly depending on locations in ak. i will have to look up the place you're at.

Place the ferrites as close as possible to the case, better to place them inside the case. All conductor runs will act as antennas and broadcast any RF being carried by them. Placing them at the radio will probably not help much, as the RF is already in the air.

Make sure the case is continuous (a Faraday cage eliminates E-field noise) and as far from the radio and receive path as possible (current, H-field, coupled noise drops rapidly with distance).

Orientation in relation to antennas can make a significant difference as well.

i should bring up that trying to isolate and cure rfi is a royal bit*#. we don't know if it is airborne or hardwire bound. we don't also know if it is just the controller or is it something else such as that particular radio. we must remember that the antennas are not located at the radio, but are most likely outside up in the air on a mast. finding and remembering these things does help in a cure as it's not always enough to just say the controller did it, what now? ground system differences or faulty grounds can also lead to problems so this is part of my reasoning to say to try to interpose or switch components from other sites to find out some of these particulars in narrowing down the causes. for example, if you take that controller that is at the site that has interference and place it at a good site and the interference goes away then i'd say look for a different cause. interchanging radios in a similar fashion helps to know if it is the radio's fault.(which i doubt, but you never know)
as was mentioned, caps and ferrite cores should be located inside the controller if possible, but at the very minimum as close to it as possible to help elilminate conducted interference through the wires and to stop the wires from acting like antennas. does the interference go away if you disconnect the coax cable from the radio? if so, then the interference is airborne and if not it's going through your dc wiring. it's alot of detective work and that's 1/2 the battle. the other half is getting rid of it, but it becomes easier to do when you know how it gets from point a(to be determined) to point b(the radio).

I've got a thread going at Outback's forum- http://www.outbackpower.com/forum/viewt ... 1848#11848

As for our pv's, they are mounted for summer sun angle and straight south. They contribute very little in the winter as they are often covered with ice or buried in snow.

ok ak. many seem to be saying as i in general and that you have to determine how it gets to the radio. power wires, antenna, or both. i didn't notice it said and maybe i overlooked it, but did you try disconnecting the antenna to see if the rf noise stays present even if only at a lower intensity? ground loops are also very possible too.
on a different note is my asking you of the usage during those winter months. do you still use the radios at that time of year? if yes, then what is powering them during those times of solar power blackout?

Techs that were on site used a handheld radio to sniff and could hear the noise inside and outside in close proximity to the hut, so pretty certain it's radiated. Also, it's actually breaking the squelch of the radio. See the outback thread, we have a new theory that we may have an accidental antenna in the form of a drain wire that's in the cable runs to the PV panels.

except for you finding that extra wire it all sounds like my advice in tracking it down. keep us informed here as well as your posts over there if you would. for the record, i have radio experience as an amateur radio operator.
gee, you think he noticed?