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Old 18-04-2019, 08:00   #1
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SSB Noise

I have an Icom 802 installed with an antenna turner and whip antenna. The installation was done according to guidelines set by DockSide Radio. I am picking up interference, enough to make it difficult to hear long-range broadcasts. I have already isolated a lot of the noise to my MPPT solar panel unit and can turn this off if needed. However, I am still getting noise from one breaker that controls the nav equipment for the vessel. I would prefer not to have to shut this one down every time I wish to use the radio. I havenít yet traced it to a specific item wired to this breaker because I do not know what to do when I find it. I have ferrites aboard and can install these if needed. But where do I install them? My understanding is the ferrites do not help on power cables, is this correct. Could someone please give me some guidance as to what to look for and how to eliminate the noise. Many thanks!
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Old 18-04-2019, 08:48   #2
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Re: SSB Noise

I think it would help everyone here if you described how you are set up. Meaning...

What kind of ground are you using?
Who, if anything, is sharing that ground?
Are you using coax? If so, from where to where?
Are you using and single wires, i.e. GTO15? From where to where?
On what frequencies do you hear the strongest noise? Or is the noise constant through the entire spectrum?

Noise is generally broadband radiated energy. I suspect you have a bad ground or you are sharing a ground point. I would start by removing the ground on the tuner side and see if the noise abates. Or, possibly find a different ground point.

JMHO
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Old 18-04-2019, 15:04   #3
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Re: SSB Noise

Quote:
Originally Posted by Brian.D View Post
I think it would help everyone here if you described how you are set up. Meaning...

What kind of ground are you using?
Who, if anything, is sharing that ground?
Are you using coax? If so, from where to where?
Are you using and single wires, i.e. GTO15? From where to where?
On what frequencies do you hear the strongest noise? Or is the noise constant through the entire spectrum?

Noise is generally broadband radiated energy. I suspect you have a bad ground or you are sharing a ground point. I would start by removing the ground on the tuner side and see if the noise abates. Or, possibly find a different ground point.

JMHO

Brian,

Thanks for taking the time to answer.

The SSB is grounded to a large dynaplate on the rudder. Nothing else is connect to this plate. Any other equipment and the vessel's bonding system is connected to the keel for a ground.

From the receiver to the tuner: M17/74-RG213 Coaxial Cable (This mil-spec coax cable is used for high frequency signal transmission.)

GTO15 wire is used from the tuner to the antenna. Connections are clean.

The noise is loudest in the middle/lower frequencies.

When you say, "I would start by removing the ground on the tuner side and see if the noise abates." Do you mean the green ground wire at the back of the Icom802 or the wire from the auto antenner tuner to the dynaplate?
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Old 18-04-2019, 15:40   #4
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Re: SSB Noise

For what is worth, our old Simrad IS-15 instruments cause RF noise that infects both our Icom IC-M710 HF radio and pocket size AM radios that share no connection to the boat's electrical system. The problem raises its head when working with weak signals.
Sniffing with the AM radios indicates that the noise originates from the Roblink cables. Years of attempts to eliminate the noise have been unsuccessful, so we just turn them off when they are a bother. The attempts include clamp on ferrites, grounding capacitors, and small inductors. None have been worthwhile.

The newer NMEA 2000 Simrad instruments on the system are quiet as a church mouse.

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Old 18-04-2019, 15:43   #5
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Re: SSB Noise

You are grounding the radio and the tuner? What is the radio grounded to? The radio already is ground via the black 12vdc wire. It does not need to be grounded again. There is a possibility you have set up a ground loop meaning... The ground lug of the radio is looping back through the dyna plate on the rudder.

Radio transmissions are AC in nature, not DC. So your antenna is 1/2 of the AC radio wave while the water (dyna plate) is the other 1/2. That RF ground is coming from the radio via the coax to the tuner then to the dyna plate.

When I mentioned that noise is generally radiated energy it is because there might be a faulty ground somewhere. Disconnecting the radio ground or the tuner dyna plate ground might stop the noise. But now you would have to find where the noise is being generated. That means turning EVERYTHING off in the boat and then turn on one switch at a time. Eventually you will find the offending item.

Do you have a refer/refrigerator? Hot water heater? Or anything with a coil? Maybe LED lights?

This will be a great exercise in trouble shooting. I envy you... not. LOL
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Old 18-04-2019, 16:33   #6
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Re: SSB Noise

Quote:
Originally Posted by Brian.D View Post
You are grounding the radio and the tuner? What is the radio grounded to? The radio already is ground via the black 12vdc wire. It does not need to be grounded again. There is a possibility you have set up a ground loop meaning... The ground lug of the radio is looping back through the dyna plate on the rudder.

Radio transmissions are AC in nature, not DC. So your antenna is 1/2 of the AC radio wave while the water (dyna plate) is the other 1/2. That RF ground is coming from the radio via the coax to the tuner then to the dyna plate.

When I mentioned that noise is generally radiated energy it is because there might be a faulty ground somewhere. Disconnecting the radio ground or the tuner dyna plate ground might stop the noise. But now you would have to find where the noise is being generated. That means turning EVERYTHING off in the boat and then turn on one switch at a time. Eventually you will find the offending item.

Do you have a refer/refrigerator? Hot water heater? Or anything with a coil? Maybe LED lights?

This will be a great exercise in trouble shooting. I envy you... not. LOL
Brian,

Nothing else interferes with the radio other than something on this one breaker. On this breaker is the ships navigation instruments (depth, wind, gyro compass, 0183 network, etc).

The radio is grounded to the dynaplate, and the auto-turner is also grounded to the dynaplate using the harness supplied by Icom. There is no other ground to the radio.

My question is really, once I find the culprit how do I stop the noise? I really do not want to shut down the ships nav system to use the radio.
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Old 18-04-2019, 16:34   #7
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Re: SSB Noise

Quote:
Originally Posted by wsmurdoch View Post
For what is worth, our old Simrad IS-15 instruments cause RF noise that infects both our Icom IC-M710 HF radio and pocket size AM radios that share no connection to the boat's electrical system. The problem raises its head when working with weak signals.
Sniffing with the AM radios indicates that the noise originates from the Roblink cables. Years of attempts to eliminate the noise have been unsuccessful, so we just turn them off when they are a bother. The attempts include clamp on ferrites, grounding capacitors, and small inductors. None have been worthwhile.

The newer NMEA 2000 Simrad instruments on the system are quiet as a church mouse.

Bill
AK4PO
Bill,

Thanks. But not what I wanted to hear
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Old 18-04-2019, 16:58   #8
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Re: SSB Noise

Well, I would start by disconnecting everything to that circuit. Then one at a time power up a device. We have to ID the offender. It could be complicated like Bill said, or it could be a bad shield in a connecting cable.

Depth, wind, and Gyro are all voltage driven. Depth and gyro are on all the time. Wind is only working when it is windy. So I would eliminate wind. NMEA is serial thus DC. I would eliminate NMEA. So that leave Gyro which might have AC voltage working somewhere in the unit.

Can you shut down the gyro without issues for testing only?
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Old 18-04-2019, 18:00   #9
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Re: SSB Noise

Most of us just turn off whatever makes noise, the only problem is if we forget to turn it back on.
Itís usually the fridge

Why not turn the Nav system off?
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Old 18-04-2019, 18:48   #10
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Re: SSB Noise

NMEA signals can certainly generate RF noise, since the signaling is a square wave, chock full of harmonics way up the spectrum. NMEA needs to be transmitted over shielded cable for this reason, even then you can get radiated noise. I would be sure all NMEA cables have shields which are single end grounded, and you might also try ferrites on each end of each NMEA cable.
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Old 18-04-2019, 18:56   #11
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Re: SSB Noise

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Originally Posted by mcerdos View Post
Brian,

Nothing else interferes with the radio other than something on this one breaker. On this breaker is the ships navigation instruments (depth, wind, gyro compass, 0183 network, etc).

The radio is grounded to the dynaplate, and the auto-turner is also grounded to the dynaplate using the harness supplied by Icom. There is no other ground to the radio.

My question is really, once I find the culprit how do I stop the noise? I really do not want to shut down the ships nav system to use the radio.
The first task is to find the culprit. I am not sure what a 0183 network is. NMEA0183 is a point to point standard. It is not meant to be networked. NMEA2000 is a networking standard.

To find the culprit you have to turn off each device powered by that circuit breaker to find which one(s) cause RF noise. Then when we know that we might be able to offer some suggestions for noise mitigation. I would start with the depth finder.

Be aware that you may end up having to turn off some nav gear during SSB transmissions anyway. Often autopilots, gyros and wind sensors freak out when transmitting on SSB.
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Old 18-04-2019, 22:22   #12
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Re: SSB Noise

Does it sound like a hash, white noise? Or more of a fast pulsating one cylinder motor boat?

The reason I ask is I have one of those homeplug systems that connects one router to another router via the power lines in my house. This network works between 3~30 MHz and is causing a fast motor boat sound on 4, 8, 15, 20 MHz but not on 7 or 14 MHz.
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Old 19-04-2019, 04:33   #13
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Re: SSB Noise

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Be aware that you may end up having to turn off some nav gear during SSB transmissions anyway. Often autopilots, gyros and wind sensors freak out when transmitting on SSB.


SSBís emit a LOT of RF, get near the antenna with a florescent tube, donít touch the antenna to see what I mean. Mine will sometimes make our LED lights flicker inside of the boat, and they are not powered.
It may not be a bad idea for expensive, sensitive electronics to be powered off during SSB transmissions?
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Old 19-04-2019, 05:31   #14
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Re: SSB Noise

I had a similar problem, lots of rf noise when the nav instruments were on. My boat is Raymarine equipped, first generation SeaTalk, and noisy. I put multiple ferrites on each and every cable coming to and from the radio, and the control head. I also put multiple ferites on the SeaTalk cables near the radio. I have more than 25 ferrites on these cables, way more than suggested. I also put a choke tube on the antenna line coming from the radio. All this did solve the RF noise problem. Maybe you have already done this, I couldn't tell from you description.
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Old 19-04-2019, 06:20   #15
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Re: SSB Noise

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SSBís emit a LOT of RF, get near the antenna with a florescent tube, donít touch the antenna to see what I mean. Mine will sometimes make our LED lights flicker inside of the boat, and they are not powered.
It may not be a bad idea for expensive, sensitive electronics to be powered off during SSB transmissions?
I donít think it will damage electronics. But it can cause some sensors to give wrong readings. An electronic compass is often pushed off course by the SSB. So autopilots sometimes make crazy course changes when the SSB is transmitting.
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