Strobe Noise In Headsets

luv2flypilot · #1 05-23-2016, 07:09 PM

I am just finishing up on an avionics panel upgrade with the panel built by SteinAir. I am still getting an ananoying strobe pulsating noise in my headsets when my strobes are on. I was hoping the new panel would cure this. I did not build the airplane and the builder used nonshielded wire to power each Aeroflash Signal power supply located in the wing tips and fuselage. It was also grounded to the airframe at each power supply with just a positive power wire ran to be power breaker and switch. I as able to use a spare wire and brought a ground to the main ground buss for each power supply however this still did not cure the problem. It will be a lot work to rerun all he cable with shielded and in speaking with Stein it still may not cure my problem since he said the older Aeroflash Signal strobes are known to be noisy. Anyone ever experience this problem and know of any filters or ideas that may cure my problem?

vlittle · #2 05-23-2016, 07:50 PM

What you are likely hearing is alternator whine as it is loaded up by the strobe power supply. I would live with it... Think of it as an audible confirmation that your strobes are functioning. You may also hear it from wig-wag lights.

On my 9A, I eliminated the noise by careful design of the alternator regulator circuit.

luv2flypilot · #3 05-23-2016, 07:55 PM

Quote:

Originally Posted by vlittle

What you are likely hearing is alternator whine as it is loaded up by the strobe power supply. I would live with it... Think of it as an audible confirmation that your strobes are functioning. You may also hear it from wig-wag lights.

On my 9A, I eliminated the noise by careful design of the alternator regulator circuit.

I have not started the engine yet. Been testing all the functions before I get it inspected by my A&P and then make an appointment with the FAA to get my limitations rewritten with a 5 hour phase testing around my airport area. Then I can put things back together and begin test flying.

rapid_ascent · #4 05-23-2016, 08:02 PM

Why don't you pull through some shielded replacement wire. Can't be that hard I wouldn't think. I kept adding more and more wires that are routed to my wingtip a couple at a time. I know this isn't the best way but it proves you can add them in at a later date.

luv2flypilot · #5 05-23-2016, 08:13 PM

Quote:

Originally Posted by rapid_ascent

Why don't you pull through some shielded replacement wire. Can't be that hard I wouldn't think. I kept adding more and more wires that are routed to my wingtip a couple at a time. I know this isn't the best way but it proves you can add them in at a later date.

May end up doing that at my next annual since I have 3 weeks to get my plane inspected, IFR pitot/static/transponder test, limitations rewritten, and fly off my 5 hours before an appointment for paint on June 16th. My panel is already installed and wired with all my wiring wax laced and neatly installed so pulling all new shielded will take some time and may find out I still have the same issue since Stein said these Aeroflash Signal strobes are known for this problem even with proper grounding and shielded cable.

rv7charlie · #6 05-23-2016, 08:34 PM

1st step, determine where the noise is entering the system. Do you hear it with the radios off? With radio volume turned all the way down? (Both comm & nav if you have 430+ type multifunction boxes.) Does a handheld portable comm pick up the noise?

Can you control the noise with the intercom volume control?

(The answers will help determine how the noise is getting into the audio system.)

If you still have the noise with all radios off, volumes down, etc, you likely have noise traveling on the power wires, either B+ or ground. Start looking at grounds. Make sure that all grounds for the avionics gear go to the firewall ground buss.

Before trying to pull new wire through the wings, you can unmount the strobes & run temporary pairs without the strobes being grounded to the airframe.

Re-check the power supplies. Disconnect the ground wires & check whether the power supply chassis is grounding directly to the airframe. If yes, unmount & temporarily insulate from the airframe & reattach your 'home run' grounds.

After each ground isolation/home run of ground, re-test.

If you still have issues, inductor/capacitor filter networks on the power supply leads may be in order.

Last (or maybe first), try to be realistic about how bad the noise really is. do you think you'll be able to hear it with the engine running?

luv2flypilot · #7 05-23-2016, 09:13 PM

Quote:

Originally Posted by rv7charlie

1st step, determine where the noise is entering the system. Do you hear it with the radios off? With radio volume turned all the way down? (Both comm & nav if you have 430+ type multifunction boxes.) Does a handheld portable comm pick up the noise?

Can you control the noise with the intercom volume control?

(The answers will help determine how the noise is getting into the audio system.)

If you still have the noise with all radios off, volumes down, etc, you likely have noise traveling on the power wires, either B+ or ground. Start looking at grounds. Make sure that all grounds for the avionics gear go to the firewall ground buss.

Before trying to pull new wire through the wings, you can unmount the strobes & run temporary pairs without the strobes being grounded to the airframe.

Re-check the power supplies. Disconnect the ground wires & check whether the power supply chassis is grounding directly to the airframe. If yes, unmount & temporarily insulate from the airframe & reattach your 'home run' grounds.

After each ground isolation/home run of ground, re-test.

If you still have issues, inductor/capacitor filter networks on the power supply leads may be in order.

Last (or maybe first), try to be realistic about how bad the noise really is. do you think you'll be able to hear it with the engine running?

Thanks for all your suggestions Charlie. I will see if he noise remains with the engine running within the next week however suspect it will since it was doing the same thing with the old panel installed and while flying. I thought about capacitors or filters but was hoping for some recommendations on what others used and where they installed them with success. I will try your recommendation of changing intercom volume etc. My new panel is a dual screen G3X Touch with GTR20 combo intercom/com radio remotely mounted behind the panel and controlled through the G3X Touch screens.

luv2flypilot · #8 05-23-2016, 11:02 PM

Anyone ever try and have any luck using a Lone Star Eliminator Filter for unwanted strobe noise in headsets? http://www.lonestaraviation.com/Eliminator-Filter.html I also read on the internet that possibly using ferrite clamps on the power wire from coming into each strobe power supply could help. For $10.49 I found a bag full of (20) http://www.amazon.com/BCP-Magnetic-F...ilpage_o00_s00. Guess its worth a shot.

greghughespdx · #9 05-23-2016, 11:59 PM

As an option, have you considered just yanking the strobes and replacing them with an electrically-quieter LED model? You might even find one that fits the same footprint. On one of my planes I pulled the strobe power supplies and tossed them (weight savings) and was able to use the existing wire/circuits to put the LED replacements in. Mine went from noisy as heck to essentially silent. every case is different. I tried to filter out ground loop noise and all it did was cause intercom problems. I never tried the ferrite clamps, would be interested to know if you try those and how it goes.

Granted, the lighting replacement option is usually more expensive than trying the filter/wire route, but it's quick and let's face it, LED lighting is pretty darn reliable as well as nice and bright. Kahuna (Mike) over at Team Aerodynamix has some good ones that he sells on their web site.

luv2flypilot · #10 05-24-2016, 08:17 AM

Quote:

Originally Posted by greghughespdx

As an option, have you considered just yanking the strobes and replacing them with an electrically-quieter LED model? You might even find one that fits the same footprint. On one of my planes I pulled the strobe power supplies and tossed them (weight savings) and was able to use the existing wire/circuits to put the LED replacements in. Mine went from noisy as heck to essentially silent. every case is different. I tried to filter out ground loop noise and all it did was cause intercom problems. I never tried the ferrite clamps, would be interested to know if you try those and how it goes.

Granted, the lighting replacement option is usually more expensive than trying the filter/wire route, but it's quick and let's face it, LED lighting is pretty darn reliable as well as nice and bright. Kahuna (Mike) over at Team Aerodynamix has some good ones that he sells on their web site.

Thanks yes definitely an option. From what I have been reading it's pretty much recommended on all lighting systems to go with shielded cable and ground only one end. If I replace my lights with LEDs will likely need to replace the cable with shielded anyways. If I can't quite down my strobe noise in the headsets I think I will live with it for 6-7 month until it comes time for my conditional inspection and replace the wiring at that point and likely put in a different system. Would like brighter landing and taxi lights than the wing tip MR16 set up anyways so likely will cut landing lights as well into the leading edges and install the bright LED flush mount Baha Designs Squadron Pro Combo lights so I have nice and bright lights for night flying.