Do you recognise this 'electronic' VHF interference?

[MattS]

It was the fact that it was coming through on both main VHF and the handheld that really stumped me. And I had initially assumed it was environmental / some kind of interference on the specific channel (it did stop if I clicked up or down a channel). But the thing that made me suspicious was that I noticed the harbour master's handheld VHFs sitting there on the same channel, neither making any noise.

 

[MattS]

So many of you were right - there's clearly something in my electrics setup causing interference!

I think I've narrowed it down to my YakMUX (NMEA Multiplexer) (although I have a Raymarine E85001 interface which also seemed to be contributing, which might be because it's connected to the YakMUX).

In this slightly cack-handed video you can see the interference stops on both VHFs as soon as I cut the power to the YakMUX.

VHF interference from YakMUX

Now I just need to work out why it's happening... for the handheld to be affected, I presume the device is either giving off something itself, or it's creating some kind of interference through the wiring that is radiating out... (technical language obviously).

 

[Plum]

So many of you were right - there's clearly something in my electrics setup causing interference!

I think I've narrowed it down to my YakMUX (NMEA Multiplexer) (although I have a Raymarine E85001 interface which also seemed to be contributing, which might be because it's connected to the YakMUX).

In this slightly cack-handed video you can see the interference stops on both VHFs as soon as I cut the power to the YakMUX.

VHF interference from YakMUX

Now I just need to work out why it's happening... for the handheld to be affected, I presume the device is either giving off something itself, or it's creating some kind of interference through the wiring that is radiating out... (technical language obviously).

Glad you have found the source. Finding out why may be harder. When I was getting vhf interference from a 12v USB charger the man from Standard Horizon said "The USB adaptor is probably using a small switch mode power supply to create the 5v. This is causing a lot of RF noise which in turn is affecting the receive ceramic filters within your radio and causing the audio shift/break up."

Www.solocoastalsailing.co.uk

 

[Boater Sam]

The voltage regulator in temperature and fuel gauges can also cause interference.
If the hand held is also affected it must be radiated interference rather than power lead fed. Faraday cage required around the YakMUX?

 

[MattS]

The voltage regulator in temperature and fuel gauges can also cause interference.
If the hand held is also affected it must be radiated interference rather than power lead fed. Faraday cage required around the YakMUX?

Is there an easy way of creating a mini Faraday cage that you know of?

 

[Daverw]

Is there an easy way of creating a mini Faraday cage that you know of?

Put it in a tin box, small cake tin would do to test, or wrap it in tin foil

 

[William_H]

A typical filter for the power supply to YakMUX or anything else consists of an inductance in series with the power wire. As said this can be in the form of a ferrite rod or torroid with wire wrapped around it (through torroid) . The wire must be capable of carrying the current of the YakMUX but best a bit bigger to make it more robust. Typical might be 20 turns of wire. On the load side you fit a capacitor to ground of several microfarrads voltage rated above supply voltage. In parallel with this capacitor you fit a small value ceramic capcitor like 1000 picofarrads. The small capacitor has less inductance than the big one so is better able to carry the high frequency component to ground. (negative wire) Make this wire as short as possible. You amy also need to fit a similar pair of capacitors on the supply side of the inductor. ole'will
L15 35x21x13mm Toroid (or Ring) Cores - Pk.2 | Jaycar Electronics or use a ferrite rod as often seen inside an old transistor radio as an aerial. or an old desctop computer will have many rings (torroids)

 

[Birdseye]

What are you doing with your thumb in the video? Are you adjusting the squelch? And how far up the scale are you going - in other words is this a real issue or just a "nice if it wasnt there" situation?

That you can get it on both hand held and plumbed in VHF shows that it is being radiated rather than travelling up the 12v line to the VHF.

What is the multiplexer for? I ask because the only time I have used one was to get old low baud 0183 or raymarine data to mix with AIS at 38400 into the single port of a Raymarine display. Is that the situation? If so, what you are likely hearing is the bursts of Raymarine data being radiated because of faulty equipment / connection somewhere.

Before you do anything else carefully check the quality of connections in your system for things like corrosion, bridging with stray wires etc. If all is OK, then the obvious item to suspect is the multiplexer.

Tracing these issues can be a nightmare. When I had ssb on my cat at first, I managed to light up the msathead tri of the boat next door when transmitting! And I regularly got audio of my transmission from the alarm circuit of the Yanmar engine control! Took me ages of logical fiddling to cure it.

 

[MattS]

What are you doing with your thumb in the video? Are you adjusting the squelch? And how far up the scale are you going - in other words is this a real issue or just a "nice if it wasnt there" situation?

Yes - adjusting the squelch up. At its worse, I can put squelch to the max and it won't prevent the interference. Best case scenario, it will stop maybe one click from the top - which also doesn't seem workable to me!

That you can get it on both hand held and plumbed in VHF shows that it is being radiated rather than travelling up the 12v line to the VHF.

Yes - and at its worse, it will interfere with the handheld out in the cockpit! And always, it seems, around channels 8-16

Before you do anything else carefully check the quality of connections in your system for things like corrosion, bridging with stray wires etc. If all is OK, then the obvious item to suspect is the multiplexer.

I'm using the multiplexer to take GPS, AIS, and Wind data, and to feed out via USB to my laptop running OpenCPN, and then also out to a YakBak Wifi gateway to get the AIS onto my iPad too). I'm also using it as a sender to send GPS out to my wind instrument, and to a GPS repeater. Everything is NMEA0183

I think re-tracing all the wiring is probably my next job. It's entirely possible I've got something weird going on, I wondered if it might be something to do with the ground somewhere...

I will try putting the multiplexer in a metal box as well, as that might show whether the radiation is coming from the device itself, or from the spaghetti of wiring somewhere...

And you're right - I can hear tones in the interference that corresponds with the data lights flashing on the multiplexer!

 

[Alex_Blackwood]

Yes - adjusting the squelch up. At its worse, I can put squelch to the max and it won't prevent the interference. Best case scenario, it will stop maybe one click from the top - which also doesn't seem workable to me!



Yes - and at its worse, it will interfere with the handheld out in the cockpit! And always, it seems, around channels 8-16



I'm using the multiplexer to take GPS, AIS, and Wind data, and to feed out via USB to my laptop running OpenCPN, and then also out to a YakBak Wifi gateway to get the AIS onto my iPad too). I'm also using it as a sender to send GPS out to my wind instrument, and to a GPS repeater. Everything is NMEA0183

I think re-tracing all the wiring is probably my next job. It's entirely possible I've got something weird going on, I wondered if it might be something to do with the ground somewhere...

I will try putting the multiplexer in a metal box as well, as that might show whether the radiation is coming from the device itself, or from the spaghetti of wiring somewhere...

And you're right - I can hear tones in the interference that corresponds with the data lights flashing on the multiplexer!

Have you tried isolating everything, I mean everything, and see if it is still on your H/H ? If not, then switch on one thing at a time.

 

[MattS]

Have you tried isolating everything, I mean everything, and see if it is still on your H/H ? If not, then switch on one thing at a time.

Yes I turned absolutely everything off (battery off) and it stops. I've tried lots of combinations of disconnecting things to see if it affects it, but it all still seems to point back to that unit. The one thing I haven't done, however, is disconnected each of the NMEA data wires from the multiplexer one by one, to see if one them is radiating the interference - so actually that would be quite a good and easy thing to do! I guess it's possible it could actually be e.g. the wind instrument causing the issue when it's connected to the multiplexer to receive GPS signal...

 

[The Q]

What are you doing with your thumb in the video? Are you adjusting the squelch? And how far up the scale are you going - in other words is this a real issue or just a "nice if it wasnt there" situation?

That you can get it on both hand held and plumbed in VHF shows that it is being radiated rather than travelling up the 12v line to the VHF.

yes, but the supply line to the piece of equipment making the noise can be acting as the aerial to transmit the noise. Stick a ferrite on it, as close as you can to the unit. they only cost pennies..

 

[ianat182]

I have recently had so much distortion and electrical crackling noise at home on our BT mobile home phone that they said they had no idea of the problem, not any of their line etc. I kept trying to figure out anything at home and just checked the phone on its stand/charger to see if it was bedded properly. The phone displayed a poor level of power so I opened the phone. Inside were the two AAA batteries that I had been sure were re-chargeable with Green top and bottom which were in fact akaline and dying; replaced both with the correct re-chargeables and Bingo! no interference at all, so cancelled the engineers visit that they were going send.
Could your radio batteries be suffering the same effect even though re-chargeable ones ?I had fitted new chokes to the line as the internet was also affected.

 

[MattS]

I have recently had so much distortion and electrical crackling noise at home on our BT mobile home phone that they said they had no idea of the problem, not any of their line etc. I kept trying to figure out anything at home and just checked the phone on its stand/charger to see if it was bedded properly. The phone displayed a poor level of power so I opened the phone. Inside were the two AAA batteries that I had been sure were re-chargeable with Green top and bottom which were in fact akaline and dying; replaced both with the correct re-chargeables and Bingo! no interference at all, so cancelled the engineers visit that they were going send.
Could your radio batteries be suffering the same effect even though re-chargeable ones ?I had fitted new chokes to the line as the internet was also affected.

If it wasn't for the fact that the interference is matched almost identically on the main VHF (12V powered) then I'd say that's a reasonable theory! But given I can walk away from the boat and the interference stops on the handheld, I think probably not on this occasion!

 

[MattS]

Just as an update to this thread now I've played around some more.

I've been playing around with various connections, and I'm now pretty sure that the interference I was experiencing is coming from the two Yakker devices I've got installed. Granted, I do have them close to the existing wiring, although I can't quite work out how they are having such a significant impact on the handheld VHF, I must admit.

The interference actually gets worse if I move the Yakker multiplexer next to my ground bus bar - is it possible the interference is being amplified / radiated by the 12v wiring? If it was all noise down the wires, I wouldn't expect it to get worse when I move the Yakker device closer to the wiring surely...?

I can make the interference stop immediately by cutting the power to the Yakker device.

Couple of videos linked below of the devices clearly creating noise when I move the handheld VHF antenna close to them. Again, this seems to suggest the interference is being radiated from the devices themselves? I don't *really* understand the physics behind this unfortunately.

IMG_4124.MOV

IMG_4125.MOV

 

[Daverw]

The Yakker devices are either faulty or very poorly designed and emitting strong RF interference. .wireing near them will act as an antenna and make this stronger still..
you either have to live with it or change them to something better as it will not fix itself and may actually get worse. Could also effect others nearby

 

[Northern Star]

Probably just the Russians preparing for their next invasion of Europe?

 

[Alex_Blackwood]

The Yakker devices are either faulty or very poorly designed and emitting strong RF interference. .wireing near them will act as an antenna and make this stronger still..
you either have to live with it or change them to something better as it will not fix itself and may actually get worse. Could also effect others nearby

It is a Wi-Fi device. Surely it is transmitting a signal on the Wi-Fi frequency range? As said local wiring acting as antenna.

 

[MattS]

To be completely fair to the Yakker devices, they're built to a price point - and I opted to go for something almost a third the price of the next equivalent thing from Quark-Elec, Digital Yacht, Actisense etc. For the price, the functionality is pretty impressive. I have been wondering whether just replacing with something like the A034 from Quark-Elec might be the sensible way forward, but it's all more £££! I will probably see if I can move them far enough away from other wiring to avoid interfering first...

 

[MattS]

It is a Wi-Fi device. Surely it is transmitting a signal on the Wi-Fi frequency range? As said local wiring acting as antenna.

The multiplexer isn't a wifi device - it doesn't have any radio components in it.

The interference still happens even if I completely disconnect the wifi component (Which is separate)