SSB Noise

[a64pilot]

It can definitely damage electronics, depending of course on field strength, distance and how well “hardened” the victim electronics are.
RF and an EMP are pretty much the same thing.

Hopefully of course if it’s Marine electronics, the manufacturer has done testing and hardened the device against SSB frequencies as an SSB is of course pretty common on boats.

I’ve done a lot of EMI / EMC testing on aircraft, and you might be surprised at what can occur, even in supposedly hardened equipment, and the failure can be degraded operation and or short term, more often than permeant damage.

The old Soviet search Radar in Kaposvar Hungary would cause a noise and glitch every computer screen on the airfield every time it would swing around, it would cause my Sony video camera to shake the video, and it was hundreds of yards away.
It never burned out anything that we know of, but we were cautioned to have our Radar receivers turned off on the airfield.

[Discovery 15797]

Not just electronics...but LEDs can also generate noise if they are on. Some are worse than others. My Lunasea bulkhead lights are susceptible to RF, but my Dr. LED are not. USGC put out a bulletin about this not long ago.

Also, wrt to ferrites there are different mixtures intended for different purposes and frequency ranges, so it is not uncommon to require a lot of ferrites not only on transmission cables, but also on power cables to equipment such as refrigerators and anything else with an electric motor (pumps, etc.), solar controllers, etc.

[Paul Elliott]

You really do want to use the proper ferrites to suppress SSB interference. Many ferrite materials are better suited for the VHF region and won't be very effective in the 3-30 MHz region. A few years ago I gave a presentation to the Singlehanded Transpac group that touched on SSB and interference:
http://sailvalis.com/presentations/S...ons%202012.pdf
Pages 11-14 have some recommendations for appropriate ferrites and how to use them.

[toddster8]

I too have interference from the NMEA0183 bus. Specifically, from the EM Trak AIS transceiver. Unfortunately, one can't just "turn it off" because it supplies time and position data to the radios and they start complaining when they don't have it! (Well, of course, you can turn it off, but...) I haven't revisited the problem in a while because the boat has been hauled and the mast down all winter. I believe I've had the system reduced to just the SSB and the AIS with no connecting wires, and the problem persists. If that's confirmed, it would seem that one or the other of these units "has to go." EM-Trak customer service just says, "our products are FCC compliant - it must be something else."

The NMEA 0183 signal is a pretty distinctive riff in 4:4 time. You can hear the music change when the satellite signal is acquired and it starts throwing position data into the rhythm. Similar (but much fainter) pulses can be heard from SeaTalk instruments when they are on.

[Pitchondesign]

Originally Posted by Paul Elliott

You really do want to use the proper ferrites to suppress SSB interference. Many ferrite materials are better suited for the VHF region and won't be very effective in the 3-30 MHz region. A few years ago I gave a presentation to the Singlehanded Transpac group that touched on SSB and interference:
http://sailvalis.com/presentations/S...ons%202012.pdf
Pages 11-14 have some recommendations for appropriate ferrites and how to use them.

Very interesting presentation. Do you know the difference between 31 material and 75 material? The 75 seems to be targeted for 200khz to 39mhz, which is the right range for marine SSB. Prior to your presentation, I had no idea ferites needed to selected by frequency.

[Paul Elliott]

Originally Posted by Pitchondesign

Very interesting presentation. Do you know the difference between 31 material and 75 material? The 75 seems to be targeted for 200khz to 39mhz, which is the right range for marine SSB. Prior to your presentation, I had no idea ferites needed to selected by frequency.

There may be better materials than the 31 for 3-30 MHz, but I think there are good reasons for choosing 31 over 75. 31 covers a broader range of frequencies, and is also useful at VHF. The 75 material starts dropping off above 1 MHz. Take a look at the datasheets for similar (but not identical) dimensioned cores in both materials:
Type 31: https://www.fair-rite.com/product/round-cable-snap-its-431164281/#selectnepart

Type 75: https://www.fair-rite.com/product/round-cable-snap-its-475164181/#selectnepart

Look at the impedance vs frequency curves.

Plus, the 75 material is more expensive.

[a64pilot]

Originally Posted by toddster8

I too have interference from the NMEA0183 bus. Specifically, from the EM Trak AIS transceiver. Unfortunately, one can't just "turn it off" because it supplies time and position data to the radios and they start complaining when they don't have it! (Well, of course, you can turn it off, but...) I haven't revisited the problem in a while because the boat has been hauled and the mast down all winter. I believe I've had the system reduced to just the SSB and the AIS with no connecting wires, and the problem persists. If that's confirmed, it would seem that one or the other of these units "has to go." EM-Trak customer service just says, "our products are FCC compliant - it must be something else."

The NMEA 0183 signal is a pretty distinctive riff in 4:4 time. You can hear the music change when the satellite signal is acquired and it starts throwing position data into the rhythm. Similar (but much fainter) pulses can be heard from SeaTalk instruments when they are on.

You could get time and positional data from a GPS, of course that is heat the AIS is using.
I use my Vesper WatchMate for time and positional data, I believe on 0183 and don’t notice any noise

[Cheechako]

Originally Posted by mcerdos

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 haven’t 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!

Welcome to HF/SSB. Not unusual at all. Pretty much the norm. A lot of things effect it, the sun, solar flares freq, time of day, how near or far the transmission comes from and which freq etc. You can try the ferrites on the wires, but likely not a huge improvement.
However if you are improved much by disconnecting those things you are
lucky at least.

[wsmurdoch]

Originally Posted by toddster8

I too have interference from the NMEA0183 bus. Specifically, from the EM Trak AIS transceiver. ..... The NMEA 0183 signal is a pretty distinctive riff in 4:4 time. You can hear the music change when the satellite signal is acquired and it starts throwing position data into the rhythm. Similar (but much fainter) pulses can be heard from SeaTalk instruments when they are on.

Same here.

I can take my little battery powered Sangean DT-400W radio, tune it to a weak AM signal, put it anywhere near a Roblink or NMEA 0183 cable on my old Simrad IS15 instruments and hear the same sound as I hear on my Icom IC-M710 when I am listening to a weak signal station. I can connect my PC to the NMEA 0183 wiring and with Paul Elliott's NavMonPC program monitor the data going by. It looks like this.

The repetitive sound from the AM radio matches the repetitive data in the NMEA 0183 signal. The sound from the AM radio is loudest when the radio is near a Roblink or NMEA 0183 cable. Pulling the fuse on the IS15 instruments stops the racket on the radios.

Bill