RFI
- Thread starter KGeorge
- Start date
schmism
Solar Addict
You might pop over to the ARRL forums. The Ham radio guys are going to be much more knowledgeable on RFI shielding.
the oversimplified EL5 version, put it in an enclosed metal box and or enclosed mesh box.
Ground loops are a thing that plague Ham guys.
the oversimplified EL5 version, put it in an enclosed metal box and or enclosed mesh box.
Ground loops are a thing that plague Ham guys.
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 21,276
Still need to pass AC and DC out of the box, desired signals but not interference.
Maybe he should put copper mesh around the PV panels?
Some of us here do EMI for a living
I work with wire routing, capacitors, signal processing ...
RFI is causing considerable noise (S9+) on the receiver especially on 7 and 14MHZ. It has been isolated to the Giandel Pure Sine 2200/4400 inverter and a minor contribution from the MPPT controller just on 7MHZ. RFI level is so high that it causes a fault light on the Tripp Lite plug strip. Inverter and receiver are about 60 feet from each other. Wondering what the best practices for this situation might be. Thanks in advance, I appreciate it. Thanks too for the reference to the ARRL.
Stay Safe,
73, KGeorge
Stay Safe,
73, KGeorge
gnubie
Solar Wizard
- Joined
- Sep 20, 2019
- Messages
- 3,844
You'll likely find ARRL points you in the direction of a low frequency inverter. They still use switchmode operation but the output transformer is very effective at knocking any noise down a lot.
That Giandel is a high frequency inverter. Frankly any of that design scream at the top of their lungs and are very difficult to make radio friendly espeically when you are trying to pull in a weak signal. High frequency designs have battery to HVDC boost power supplies in them, which generate fundamentals around 100kHz - 300kHz and then they add the 20+kHz PWM fundamental on top of that both with high harmonic content and push the noisy lot through an output inductor which is often poorly designed and materialled (made that word up ) and do a poor job of filtering all the HF crap off the AC output, especially under high loads.
You've probably done it all already but earth the chassis of the inverter put decent RFI filtering on the DC input and do what you can with the AC side. Take care with grounding issues vs neutral earth bond as per usual
That Giandel is a high frequency inverter. Frankly any of that design scream at the top of their lungs and are very difficult to make radio friendly espeically when you are trying to pull in a weak signal. High frequency designs have battery to HVDC boost power supplies in them, which generate fundamentals around 100kHz - 300kHz and then they add the 20+kHz PWM fundamental on top of that both with high harmonic content and push the noisy lot through an output inductor which is often poorly designed and materialled (made that word up
) and do a poor job of filtering all the HF crap off the AC output, especially under high loads.You've probably done it all already but earth the chassis of the inverter put decent RFI filtering on the DC input and do what you can with the AC side. Take care with grounding issues vs neutral earth bond as per usual
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 21,276
EMI is often conducted out the wires of a device, may radiate from there.
If the MPPT has arc-fault function, you don't want to put any filtering on the PV wires that would defeat that function.
Is your receiver operating off the inverter? Or another source?
Operating the receiver with just inverter, just MPPT, neither, is a way to isolate them.
Operating those PV systems with no conducted path to receiver, completely isolated from each others wires, separates radiated from conducted.
Radiated interference may come from a wire loop, e.g. PV positive and negative being spaced apart. Routing wires together, maybe twisted, can help.
The panels form a loop. loops which are oriented differently (similar to a loosely twisted pair of wires) would cancel vs. all loops oriented the same. At 7 MHz and 14 MHz, wavelength is quite long compared to panel size, so this "twisting" could be effective to reduce radiated power from any noise conducted on PV wires from MPPT.
Loops can also be an issue with AC wiring, but less likely there is a loop. The wire can carry common-mode noise, radiates like a car antenna.
Putting AC wire a couple turns through a large ferrite (selected for the frequency of interest) can help.
Connecting hot and neutral wires through a "common mode choke", a 4-terminal device, can help.
Additional chokes, not common-mode (and therefore beefier) may help with that noise gnubie mentions.
That's a place to start; let me know how that goes.
The way AC wires are connected in a device can make it hard to suppress. Possibly an isolation transformer outside inverter would help. But that is big iron, able to handle 3 kW, and needs to be selected to not couple the common mode noise through. So save that for later.
Fault on the tripp-lite strip is interesting. What function is the strip supposed to provide?
If the MPPT has arc-fault function, you don't want to put any filtering on the PV wires that would defeat that function.
Is your receiver operating off the inverter? Or another source?
Operating the receiver with just inverter, just MPPT, neither, is a way to isolate them.
Operating those PV systems with no conducted path to receiver, completely isolated from each others wires, separates radiated from conducted.
Radiated interference may come from a wire loop, e.g. PV positive and negative being spaced apart. Routing wires together, maybe twisted, can help.
The panels form a loop. loops which are oriented differently (similar to a loosely twisted pair of wires) would cancel vs. all loops oriented the same. At 7 MHz and 14 MHz, wavelength is quite long compared to panel size, so this "twisting" could be effective to reduce radiated power from any noise conducted on PV wires from MPPT.
Loops can also be an issue with AC wiring, but less likely there is a loop. The wire can carry common-mode noise, radiates like a car antenna.
Putting AC wire a couple turns through a large ferrite (selected for the frequency of interest) can help.
Connecting hot and neutral wires through a "common mode choke", a 4-terminal device, can help.
Additional chokes, not common-mode (and therefore beefier) may help with that noise gnubie mentions.
That's a place to start; let me know how that goes.
The way AC wires are connected in a device can make it hard to suppress. Possibly an isolation transformer outside inverter would help. But that is big iron, able to handle 3 kW, and needs to be selected to not couple the common mode noise through. So save that for later.
Fault on the tripp-lite strip is interesting. What function is the strip supposed to provide?
Hedges
I See Electromagnetic Fields!
- Joined
- Mar 28, 2020
- Messages
- 21,276
Perhaps tripp-lite should be left in, and spikes from inverter fixed so they don't trip it! It was obviously trying to tell you something.
Got any suitable equipment to observe the AC waveform? It may be carrying steps or spikes from 200 kHz switchers. I've seen that, a hash of noise from 100 MHz to 200 Mhz coming from a fat-snake power cord. Varying schemes of carrying ground from AC plug through the adapter into the device made a big difference.
I see some filtered plugs at DigiKey, 20 to 30 dB attenuation. Maybe not as much as you want.
Got any suitable equipment to observe the AC waveform? It may be carrying steps or spikes from 200 kHz switchers. I've seen that, a hash of noise from 100 MHz to 200 Mhz coming from a fat-snake power cord. Varying schemes of carrying ground from AC plug through the adapter into the device made a big difference.
I see some filtered plugs at DigiKey, 20 to 30 dB attenuation. Maybe not as much as you want.
Pierre
Somewhere down South
- Joined
- Dec 21, 2019
- Messages
- 1,143
Is the interference getting into your rig via antenna or power supply cable ? Sorry if it was stated above somewhere.
Maybe terminate antenna socket into a pure 50 ohm dummy load and re-do the tests. At least that will determine how the RFI is getting into the RX/TX. Maybe you know another ham with a spectrum analyzer.
73’s de ZS1AP
Maybe terminate antenna socket into a pure 50 ohm dummy load and re-do the tests. At least that will determine how the RFI is getting into the RX/TX. Maybe you know another ham with a spectrum analyzer
.73’s de ZS1AP
Also see:
diysolarforum.com
As I noted here an ARRL search for inverter RFI gives you 134 hits:
diysolarforum.com
Search this forum for RFI and get 3 pages of hits.
Looking for HAM radio operator's advice.
Hello HAM's W1SMM here. I'm looking for advice on an RF quiet 40-60 amp 12/24v solar charge controller as well as a 2-3kw 12/24v AC inverter, or an equivalent All-in-One such as the MPP or Growatt. Anyone have some good experience to share? The system I am building will be in my HAM shack I'm...
diysolarforum.com
As I noted here an ARRL search for inverter RFI gives you 134 hits:
Inverter with low RF, EMI noise/interference ? 2000W/24V
Hello, Does anyone know of any quality inverter with low or non existing interference with my HAM radio equipment ? So far most of them I tested (mostly chinese made) produce a lot of noise. Looks like Samlex is one of the better ones, is there anything else on market worth looking at? The specs...
diysolarforum.com
Search this forum for RFI and get 3 pages of hits.
Joe BoyKey
Watts, Watts, more Watts
Just fyi, when I saw Fault light triggered, it reminded me of this article, blew up my mpp running thru a step down auto-transformer and fried the surge arrestor to pieces - Auto transformer passes one leg of input thru to output, isolation transformer does not, Joe
Joe BoyKey
Watts, Watts, more Watts
understood isolation transformer 
Auto-tap transformer
Auto-tap transformerHi KGeorge
I had the similar problem. I'm a SWL with an R1000 and an 897D
I chased everything down built 240v ac filters for the Giandel 240v 2.200w pure sinewave inverters
But my issue turned out to be a shared earth with the radio's and the panel frame earth.
I gave the their own earth and the further I moved the earth from the frame earth the better it got
So it's moved about 10ft apart
Now I can here a lot of W calls on 40m with a very low dipole from the southwest slopes of NSW in OZ
Might be worth a look
Cheers
Andy
I had the similar problem. I'm a SWL with an R1000 and an 897D
I chased everything down built 240v ac filters for the Giandel 240v 2.200w pure sinewave inverters
But my issue turned out to be a shared earth with the radio's and the panel frame earth.
I gave the their own earth and the further I moved the earth from the frame earth the better it got
So it's moved about 10ft apart
Now I can here a lot of W calls on 40m with a very low dipole from the southwest slopes of NSW in OZ
Might be worth a look
Cheers
Andy
gnubie
Solar Wizard
- Joined
- Sep 20, 2019
- Messages
- 3,844
How far down do you think it knocked the noise? I'm asking because I've had amateurs complain about noisy HF inverters that haven't been able to improve things acceptably, my brother included. Proper earthing has knocked it down but not enough.
Pierre
Somewhere down South
- Joined
- Dec 21, 2019
- Messages
- 1,143
There is nothing to compete with a good old transformer based power supply for ham use. Been there , done that.
de ZS1AP.
Similar threads
