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Interference from strobe on my frequency

10 Posts

I replaced my GNS430W with an Avidyne 540. Now everytime somebody transmits (not me) on the selected frequency I clearly hear three pulses that correspond to the strobe flashing sequence. Now here is my question: will I get rid of this noise when I replace the old fashioned strobes (and powerpack) with the LED variant ?

EBST, Belgium

At least not guaranteed 🙁 A friend of mine has three Whelen strobes (synchronized) in his TB10 and you can hear them even on the intercom. I have the same Whelen strobes, synchronized as well and there is nothing to hear.

EDFM (Mannheim), Germany

You gotta love aviation 😅

EBST, Belgium

The grounds need to be routed correctly, so the return current does not flow through the wing – search.

In GA, most installers just forget to do that and return what they can via the airframe. You get all kinds of fun… with a fluxgate too.

I went from Whelen conventional to Whelen LED, with no issues with either.

Administrator
Shoreham EGKA, United Kingdom

Yes, LEDs are supposed to give much less interference than conventional xenon-filled strobes. A gas discharge strobe is essentially a spark-gap transmitter. The current pulse in LEDs is much smoother, so the radiated high-frequency power is much lower.

LKBU (near Prague), Czech Republic

The LED “strobes” just have a big LED array which is turned on and off. It’s nowhere near as bright as the old strobes but it is “good enough”; same comment could be made for phone cameras. The interference probably comes from a switch-mode power supply driving the LEDs; most big LEDs are driven that way because the simple way – dropping some volts in a resistor – produces a lot of heat. Another bad design, and would be helped by shielded cable, and not using the airframe for the ground return.

Administrator
Shoreham EGKA, United Kingdom

would be helped by shielded cable

I guess the current cabling is not of the shielded type ?
Any opinion on how Whelen designed their LED nav/strobes ? Those are the ones that would eventually go in.

EBST, Belgium

They seem well made, but I have noticed that – like most “outdoor” electronics – they are not sealed, relying on a drain hole instead. That will limit their life.

Moisture is what kills most LED lamps. I have some outdoor lights which are on all night and they are now LEDs and those don’t last any longer than the previous fluorescent types – about 1 year. An LED lamp should last much longer (there is actually a degradation mechanism).

I would hope the Whelen ones are conformally coated – will take a look next time I fly.

Administrator
Shoreham EGKA, United Kingdom

I have the AeroLED strobes and hear nothing from them on the radio, very clean. But as mentioned by @Peter, the key is a proper and clean installation of grounding. Any avionics tech worth his salt should know that and not cut corners. “Forgetting” to do it properly would have me looking for a new avionics shop.

LSZK, Switzerland

looking for a new avionics shop.

…and there lies another big problem!

EBST, Belgium
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