Marine Safety alert, LED lights and VHF

[a64pilot]

Originally Posted by Wild Cherry

I've just ascertained from the Dolphin online users manual that AGM's require the same charge rate as Gel batteries i.e. 14,4 volts absorption and 13,8 volts float.

Do not go by the chargers Manual, often batteries are different, go by your battery manufacturers recommended voltages.
For example my AGMs require 14.3 absorption and float at 13.3, an extra half a volt over months may kill them

[Cpt Pat]

Originally Posted by trifan

If I'm chasing a noise problem I borrow a spectrum analyzer and watch the noise floor. If it is for local signals, a paper clip antenna usually couples enough signal to see what's happening. Ok, so for those not so lucky as to have a friend with a $40.000 analyzer, disconnect the VHF antenna, put a paper clip into the center pin of the radio's antenna connector (DON'T TRANSMIT!!!!) and have someone some distance away send a signal (or tune into a beacon signal) and then switch on the LEDs and see if their signal either goes away or gets noisy. It's better if you have a variable attenuator but what boater has one of those in his kit? Anyway, basically you need to start off with a weak signal and see if the suspected noise source drowns it out when turned on. - Later ...

A spectrum analyzer is the best tool, but a good one costs at least $10,000. The Coast Guard procedure in the linked article won't work with many modern radios that need a coherent RF signal to open the squelch. Random noise from bad LEDs won't be detected using their procedure with those radios.

Everyone here has identified the primary cause of the problem: cheap LEDs. Here's a little more. Without a regulator circuit, LEDs will dim when the voltage is reduced, and they will only work over a very narrow voltage range. Those LEDs will NOT make RF noise.

Manufactures add a regulator to allow the LEDs to operate over a broad range of voltages without dimming or over-voltage failure. It's those regulators that cause the RF noise. They use a variable duty-cycle solid state switch and a small capacitor accumulator to maintain a constant voltage at the internal LED terminals. That switch, usually a MOSFET, has a rapid slew-rate that generates RF noise in the VHF and UHF spectrum. If the noise isn't suppressed - usually by reducing the slew-rate - it gets radiated by the LED case and power supply wiring throughout your boat.

It costs only a few extra cents to add RF suppression, but the United States doesn't have any regulatory authority to enforce the use of RF suppression. US manufacturers can "self certify" that honest, trust us, cross-our-hearts: our lamps are RF quiet. And the manufacturer makes a few extra cents per lamp by omitting the circuitry.

We've all heard how one particular political party hates government regulation, so the situation here in the US isn't likely to change - even if it means vessels getting run over by container ships and the Coast Guard being unable to communicate with vessels.

The European Community DOES require suppression and the lamps must be tested in a lab with - guess what - a spectrum analyzer. So looking for lamps with the "CE" symbol should be your first step to avoid the issue.

As a practical test, I suggest this procedure instead of the Coast Guard's:

1. Turn off all LED lamps.
2. Tune in the weakest NOAA weather channel on your most critical VHF transceiver.
3. Turn on your LEDS, one at a time.
4. If the NOAA channel vanishes after a lamp is energized, it's generating RF interference.
5. If all the lamps are energized, and the NOAA channel is still receivable, you MAY not have an RF interference problem.
6. In some cases, generation of the RF interference may be voltage dependent, so if the supply voltage changes, the problem my emerge even when the test above shows no problems.
7. So don't buy cheap lamps.

But, as stated, a spectrum analyzer is the best tool for identifying the presence and source of RF interference. You saved a few bucks with cheap lamps, now you need a $10,000 test instrument to verify you aren't in trouble.

I have LED deck lights that wipe out the entire VHF band - destroying all VHF reception including AIS - and even FM broadcast stations. I just limit my use of those deck lights to avoid the problem. If it were my navigation lights, I would have to replace those lights.

-Patrick Bryant
N8QH
FCC licensed GMDSS Maintainer

[Nicholson58]

The LED issue is so easy. The PWM circuit needs to operate outside the interference frequency of your radio and it needs to be suppressed. This does no require government intervention. We buyers are in control here. If you are willing to buy cheap junk without supporting vendor data you deserve the results. Don’t buy LED replacements from NAPA. They are made for cars and trucks without a VHS or SSB and with a constantly running alternator. These are not for boats. Further, there are vendors selling so called marine rated LEDs and replacements that are worse than inferior. They likely give short life and may also induce radio interference.

https://store.marinebeam.com/about/

We have used IMTRA and Marine Beam replacements and new fixtures. We have no RF interference issues. There are other quality makers as well. You get what you pay for and if you shop by price alone you get what you deserve.

[CharlieJ]

a64Pilot #15 has provided good advice; Dolphin has not!

Here is the link to the Victron data sheet for your batteries: https://www.victronenergy.com/upload...tteries-EN.pdf

If you follow Dolphin's advice, you will be murdering your expensive batteries.

A couple of points with thin plate pure lead (TPPL), and in general all AGM batteries to maximize their service life:
1. Charging sources must use temperature compensation at the battery and the TC must be set IAW the battery manufacturer's specs.
2. AGM's, and especially TPPL AGM's, must be fully recharged very soon after they have been discharged. What does "soon" mean? Hours, not days. What does "fully recharged" mean? Fully recharged. If you don't, you are eating into the cycle life.
3. Set the bulk/absorption knee voltage, the absorption time and the float voltage IAW battery manufacturer's specs.

[wkearney99]

Originally Posted by Nicholson58

You get what you pay for and if you shop by price alone you get what you deserve.

This.

It's good the Coast Guard has raised this issue.

Lots of folks have been assuming there's no point in spending more to get better light elements. No doubt never actually checking that their VHF still works effectively after the cheap crap was installed. Hell, they might not even have ever known if it was working properly to start, let alone after the LED changes.

[Cpt Pat]

Originally Posted by wkearney99

This.

It's good the Coast Guard has raised this issue.

Lots of folks have been assuming there's no point in spending more to get better light elements. No doubt never actually checking that their VHF still works effectively after the cheap crap was installed. Hell, they might not even have ever known if it was working properly to start, let alone after the LED changes.

I'll second all that.

By now, the problem shouldn't be a surprise to anyone. There are some good (and old) threads here on CF with testimonials on bad LEDs creating radio frequency interference (RFI). Here's one: https://www.cruisersforum.com/forums...p/t-36083.html. Search the thread for "RFI".

I would like to believe that "market forces" could eliminate the need for regulations, but the issue is too complex for many consumers, and require specialized skills and expensive tools to identify. Do you want to know which food is unsafe only by first experiencing food poisoning? Some LED manufactures have a long well-know issue with RFI; but there they are, still on the shelf.

[KP44]

Originally Posted by Suijin

I have a “native” LED masthead tricolor/tricolor right adjacent to my VHF antenna and have not had any issues with VHF or AIS reception but it might be degraded. We’ll see.

I will consult with other HAMs on this. It is interesting and antenna filters for specific frequencies or harmonics could be helpful.
I have excellent VHF even though the lead from antenna is about 80' (60' mast). But I have not tested the VHF with the mast-top tri-color on. Mine is retrofitted with LEDs, both tri-color and anchor.
It will be interesting to do this squelch test when we return to the boat this winter.

[deluxe68]

Originally Posted by a64pilot

My Bendix King KX-155 if the Nav half was tuned to a specific frequency it would cause my Garmin handheld to lose all Satellites. This confused me as it was a receiver only, not a transmitter.

EMI / EMF testing flight tests your really looking at other systems not the radios, for instance the system used at Ft Ord to track vehicles would “get into” the Mux Bus on an AH-64 when transmitted and shut down the Fire Control Computer, but it did it so intermittently and only on some aircraft it was hard to pinpoint.
It seemed the 1553 Data Bus that was used wasn’t very well shielded.

Point being I guess it that it can be indiscriminate, meaning it can cause havoc one day on one freq, and tomorrow it won’t.

I used to be a back-end crewmember on the E-4B, and when Reagan was President we would pull alert at March AFB when he was at his ranch. When we transmitted (cannot remember which band) a few hundred garage doors in Riverside would open or close.

[donradcliffe]

Originally Posted by Nicholson58

If you use cheap replacement bulbs, especially from automotive suppliers, you may be more likely to have issues. Proper LED bulbs use pulse width modulating current control PWM. The switching frequency must be above the frequency to cause radio interference. Try Maine Beam replacements https://store.marinebeam.com/?gclid=...gaAnGLEALw_wcB. There are many other quality replacements available but the cheap stuff is just that.

This is way off base. The cheaper LEDs use resisters to control the current, and have no RF emmisions. The RFI COMES from the PWM current control circuits.

We had RFI trouble with an Aqua Signal LED tricolor fixture (not LED replacement bulb), so bought a MarineBeam fixture--its RFI was as bad or worse. None of the manufacturers seem motivated to fix the problem, but are rumor of a Brazilian company who has.

[bletso]

Originally Posted by Cpt Pat

The European Community DOES require suppression and the lamps must be tested in a lab with - guess what - a spectrum analyzer. So looking for lamps with the "CE" symbol should be your first step to avoid the issue.

-Patrick Bryant
N8QH
FCC licensed GMDSS Maintainer

Thanks for reminding me of that. I have had a lot of business in the EU since early 90's.

[Viking Sailor]

Also, you might want to include solar controllers as they are a known source of EMI/RFI.

[hzcruiser]

Originally Posted by Nicholson58

[...] Proper LED bulbs use pulse width modulating current control PWM. [...]

Hmm, so what do the cheap ones use?

[hzcruiser]

Originally Posted by Viking Sailor

Also, you might want to include solar controllers as they are a known source of EMI/RFI.

And fridges and freezers.

[Paul Elliott]

Originally Posted by Cpt Pat

The European Community DOES require suppression and the lamps must be tested in a lab with - guess what - a spectrum analyzer. So looking for lamps with the "CE" symbol should be your first step to avoid the issue.

The CE test limits aren't much tougher than the FCC Part-15 limits. Either of these is a good start, but neither one is nearly enough to ensure that your masthead tri-color won't interfere with your adjacent VHF or AIS antenna. These FCC and CE rules are designed to limit interference to nearby televisions and the like -- not to an antenna located within one meter from the device in question.

And yes, a good spectrum analyzer can cost tens of thousands of dollars. An adequate one, perhaps $700 (the Rigol DSA700). You can also get a $120 Software-Defined Receiver from SDRplay that can be be used as an uncalibrated spectrum analyzer. But you honestly need to know how to use this gear before you will be able to draw any serious conclusions.

[Cpt Pat]

Originally Posted by Paul Elliott

The CE test limits aren't much tougher than the FCC Part-15 limits. ...

True, but the FCC lets manufacturers "self-certify" RFI in the VHF range whereas CE requires lab tests for certification.