VHF send issue, buzz sound

SG · Oct 21, 2018

Okay, transmit with the handheld to boat or land station ONLY. Go ashore away from the boat. Make sure it's FINE in transmit mode.

First with the engine off AND (if you have an inverter/charger, make sure it's OFF and not producing either DC or Inverting, producing AC). EVERYTHING OFF. Do this after the battery is down a bit. (Just enough to demand a charging later). Make sure the inverter switches (if you have them, are set to OFF, no charge, no invert). NO SHOREPOWER (turn-off the AC at the dock, turn off the AC main breaker on the panel).

Now start the engine, make sure it's in neutral gear and rev the engine up to about 1800 RPM. Try the handheld. Does it transmit with noise? Move around the cockpit to the bow, if it does. Now move below and try to the same thing. See if the handheld does anything.

Now you start turning things on, one- by one-, moving around and seeing if the background interference or noise reappears. Start with the inverter, if you have one. First with the inverter in standby (no AC load on the boat). Now, with the microwave your TV or whatever on. You can stay below near the inverter, but also check the charger. Check the main VHF too as you do this.

The noisiest item on our boat used to be our inverter on our previous boat. We had a Heart Freedom modified sine wave inverter. It had a hum that we finally filtered-out. In your case (as Brian D suggests), it appears to not be directly from your DC wiring -- but, who knows?

As you move around you should find it stronger with the handheld in some locations. I would think it's going to be in the cabin or cock-pit.

You get the general methodology....

Brian D · Oct 21, 2018

OK... DC, or direct current, does not radiate. A radiated signal needs to have a sinuous wave. Plus. it needs a radiator, or an antenna. So what on a boat produces sinuous waves? Any thing that is AC, or alternating current, producing. The very first thing I would look at would be an Inverter if you have one. It could be failing and using any wiring as an antenna. Next down the AC line would be Air Conditioners, Fridge, Microwave, and so on. But not all of these would be on when sailing. So look for items that are active when you are on the water and at the dock.

I am sure you have done this, but leave someone on the boat and take a walk with the handheld. Go to a parking lot or something. Find a seldom used channel and talk to them. Or you can stay on the boat and let someone take a walk. Either way, get the handheld out of the boat's interfering field.

Ah... I see SG and I are transmitting on the same channel. LOL

Meriachee · Oct 21, 2018

Brian, don’t forget to account for pwm in a led driver. Stranger things have happened.

Rick D · Oct 21, 2018

FWIW, while my marine radios do not have any interference, my ham radio on 2 meter does from three sources: frig, freezer, inverter / charger. I have to remember to shut them off when transmitting. Good luck; sounds like a real diagnosis challenge that you are handling fine.

jssailem · Oct 21, 2018

Brian D said:
DC, or direct current, does not radiate. A radiated signal needs to have a sinuous wave. Plus. it needs a radiator, or an antenna. So what on a boat produces sinuous waves?

So True Brian... AC can be a culprit.. But????

Some LED lighting products have been reported to emit noise, interfering with FM radio and DAB signals. While the Light Emitting Diodes themselves do not generate any detectable noise, the switching power circuitry driving the LEDs operate at high frequencies, which, when not properly filtered can result in electromagnetic interference.

Based on the reported experiences of some LED users, interference issues and, occasionally EMC violation, can arise as a result of radiated emissions in the 30MHz to 300MHz range by some LED products. The LED lights most commonly involved are of fixture type MR16 (more correctly GU5.3), however radiated emissions have also been observed in other fixture types including GU10, E27 and B22 designs. In the case of MR16 lights, the radiated noise signals would most likely be the result of the electronic transformers driving them rather than the lights themselves.
Why would this be of consideration?
- Very high frequency (VHF) is the ITU designation[1] for the range of radio frequency electromagnetic waves (radio waves) from 30 to 300 megahertz (MHz), with corresponding wavelengths of ten to one meter.

Brian D · Oct 21, 2018

So very true, John. I was going to give a caveat but it would be too long and drawn out. The only issue I have with what you have said is the interference should be detected on receive. I understand the concept of FM but if the signal was strong enough to be detected by the Transmit circuit, it should be strong enough to break squelch. Unless the squelch is set so high because the noise was bothersome. But your point is valid.

Just so you know, I have found a couple of forums and threads with the basic same issue. However, unlike SBO, those forums and threads did not list the culprit or the solution. Let's not let that happen here.

jssailem · Oct 21, 2018

I tried to give @gertonw enough of the typical checks to at least reduce the number of offenders so that he could isolate the issue AC/DC, on boat or off boat, etc.

If anything the folks on SBO appear to be a bit tenacious and not let an issue go unresolved. Even if we come back to it several months/years later and ask about the issue...

It is one of the aspects I love.

JimInPB · Oct 21, 2018

In addition to LED drivers, some other "allegedly DC" devices that are not true DC & are sometimes capable of putting out a carrier wave would include DC to DC converters (phone chargers, laptop chargers, etc), & some regulator circuits.

Since the freezer was found to be the culprit, I'm going to assume that it runs off of an electric motor? Electric motors can throw off a lot of hash. If you topped off the refrigerant in the freezer, then the compressor may need more torque to turn it now, which would then make the motor draw more current, which would then strengthen the em field that is generated by the motor & it's wires.

If your handheld has the same hash issue, then your problem is not in the wiring from your installed VHF to the buss bar.

SG · Oct 21, 2018

Rick, you da man! When fridge and/or freezer switch on, I get the noice. We did some maintenance (top off) to both. Did I screw something up there?
The ground/negative of the VHF is connected to a central bus in my console. Shall I connect direct to negative of battery, or ground to engine to circumvent?
My autopilot (old Raymarine ST5000) had erratic behavior as well. Could that be related?

What is the refrigeration system you have? You might talk with them, look at their website, check their "blog" (if they have one); and search the web for some info.

It may be localized to the compressor circuitry or it might be passed through the ground or otherwise. Grunert, (now owned and marketed by Dometic) for example, takes DC power and inverts it to run the compressor on AC. At least some of their systems have been doing that successfully for over 40 years.

There are some filters that you can put on the equipment wiring to keep it from passing it beyond the unit. You can try to just develop move direct dedicated ground -- and see if that works. Be careful for a path that may not be protected by your sacrificial zinc(s) for electrolysis. You might (I'm just guessing here) run a PROPERLY SIZED ground wire directly from the refrigeration equipment to the engine ground.

At lease you have a cause
Rick is wins 'da man prize ;^)))

Tally Ho · Oct 21, 2018

So, if the LED lights are OFF, I assume there would be no potential interference? In other words, it is easy to check whether the LED lights are causing interference...just switch off the power for the cabin lights...

Am I thinking about that right?

Greg

Brian D · Oct 21, 2018

Tally Ho said:
So, if the LED lights are OFF, I assume there would be no potential interference? In other words, it is easy to check whether the LED lights are causing interference...just switch off the power for the cabin lights...

Am I thinking about that right?

Greg

Yep, start off by turning everything off. And I mean everything. Won't be off long enough to spoil the frozen steaks.

Rick D · Oct 21, 2018

gertonw said:
Rick, you da man! When fridge and/or freezer switch on, I get the noice. We did some maintenance (top off) to both. Did I screw something up there?
The ground/negative of the VHF is connected to a central bus in my console. Shall I connect direct to negative of battery, or ground to engine to circumvent?
My autopilot (old Raymarine ST5000) had erratic behavior as well. Could that be related?

I'd start by cleaning up all the grounds, and then cleaning/checking the refrig/freezer leads at the compressors and panel. Others may have better advice. I assume the two ships radios (did I assume that correctly?) have different antennas. I am also assuming this noise was not there before. Anyhow, good luck! At least you have it narrowed.

SG · Oct 21, 2018

Do I have a crossed ground in my panel, or one missing?

Gerton W - The idea of "the ground" is that its 'Common' and the 'same'. If you have differences in "potential" between the "ground", you'll have problems.

If you cross a "positive" (or 'hot') and a "ground", you get BIG current flow. (Like sparks and huge amounts of transfer of energy.) If you have different levels of 'ground', you would have current flow between then you'd have things that cause electrolysis and other not-good-things.)

Not having a "good ground" is usually that you've interfered with ability of the current to go-to-ground and complete the circuit.

I really think you should invest in a simple book on electrical power for boats.

SG · Oct 21, 2018

What is also new I discovered today, that if I want to switch on a light, I also have to have the courtesy lights enabled on the panel, besides the regular overhead lights switch on the panel?

Gerton: What do you mean? That when you turn on the circuit breaker on the panel, the courtesy lights go on -- regardless of whether you turn-on an individual "reading" or other light fixture? Do you mean that you can only turn-on a light, if you have the courtesy lights 'on' or 'burning' (like in candelabra ;^))) )?

SG · Oct 21, 2018

Did the switches do what they "are supposed to" before while you've owned the boat?
Did you touch anything in the panel or "along" the way to the one of the lights or replace (or add) a light fixture?
Something is amiss, unless there is electrical "voodoo" afoot.

Do you have an simple electrical meter that sense 12VDC voltage?
The paths for the two systems systems are supposed to be discrete, the common ground is generally supposed to be in the panel at the "bus" -- not down the circuit. The courtesy lights (at least in my boat) are either on-, or off-. The lights are enabled so that you can then control each fixture at its own switch (if you leave the switches "on", then switch the breaker 'on' lights each fixture that itself is swiched on at itself).

Do you have an simple electrical meter that sense 12VDC voltage?

VHF send issue, buzz sound

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SBO Weather and Forecasting Forum Jim & John

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SBO Weather and Forecasting Forum Jim & John

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