nuckolls.bob(at)aeroelect
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 Posted: Tue Mar 29, 2016 7:24 am Post subject: How do I stop audio hash noise generated by a new set of N |
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At 09:52 PM 3/27/2016, you wrote:
| Quote: | --> AeroElectric-List message posted by: DeWitt Whittington <dee.whittington(at)gmail.com>
Hello, Bob, and all you AeroElectric forum participants. This is the first time I’ve posted in years, but I’ve got a problem I can’t solve. At Oshkosh 2015 I bought a set of the NavStrob LED nav/position light units. They directly replace the red and green wingtip nave bulbs, and the white rear position light. I cleaned out the sockets for all three locations and sprayed them with CorrosionX. Then inserted the NavStrobe units. When you turn on the Nav light switch once, all three burn with a steady light. Flip them off, and turn on again, and they flash like strobes. Slick. But, in my 1975 172L, when we turn on the COM radios, then turn on the strobes, there is a very unpleasant “hash” noise when the VOX gate opens as when you speak or a transmission comes in from someone else.
The designer of the NavStrobe unit suggests cleaning all the light sockets again. And if that doesn’t get rid of the hash noise (and it didn’t) install a choke coil.
So, any suggestions? And what size or type of choke should I buy and where do I install it? All suggestions welcome. |
Are they ever supposed to flash?
These devices SHOULD contain little DC/DC constant
current converters that are a special form of switchmode
power supply. Some years ago I crafted and sold a
filter assembly to accept the DC/DC converter recommended
for popular DIY nav light project. I sold several
dozens of these assemblies with no complaints/returns so
my sense is that they performed as adverstised to
stand off the VHF radiated noise from the Luxdrive
module.
You MIGHT be experiencing a similar condition.
Do I presume correctly that you're working with devices that look like
this?
[img]cid:.0[/img]
Kinda cute . . . but not very reassuring from the perspective
of design for EMC. Minimized radiation from high frequency
power supplies BEGINS with tightly clustered components
with short leads to minimize the radio frequency radiation
footprint. That sprinkling of parts gives pause for doubts.
If your lamps are different, shoot me pictures or links and
a link to the installation instructions. We may have to
conduct some experiments to identify the noise propagation
mode . . . Might have you send me one to bench check. I just
bought a spectrum analyzer that would help identify the device's
un-neighborly behaviors.
Bob . . .
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