Today's Message Index:
----------------------
1. 06:26 AM - Re: Re: Intercom feedback at low rpm (Charlie England)
2. 03:52 PM - Re: Intercom feedback at low rpm (Rebel56)
3. 06:50 PM - Re: Re: Intercom feedback at low rpm (William J Hamilton)
Message 1
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Subject: | Re: Intercom feedback at low rpm |
On Sun, Jan 14, 2018 at 8:53 PM, Rebel56 <Rebel56@rogers.com> wrote:
>
> [quote="ceengland7(at)gmail.com"]On 1/14/2018 8:39 PM, Rebel56 wrote:
>
> >
> >
> > Been a while since I flew, but I think it could be both, a slight
> whine, and static. I can quiet it with the squelch, but doing so also
> quiets all radio traffic.
> > Who were you answering? (Need to quote the person you're replying to, if
> >
>
> there are multiple possibilities.)
>
> If it was me, does it change frequency with engine rpm?
>
> ---
> It might change frequency ever so slightly, bu the static is constant and
> loud.
>
If it doesn't change pitch or volume, it would seem to be unrelated to the
engine itself. Have you shed all electrical loads, except the intercom
itself? Try to eliminate every electrical device, to see if the noise stops
after dropping one of them off line. Any device that contains a 'switcher'
style power supply can generate a buzzing noise if it isn't properly
filtered. USB power supplies, both LED & HID lighting, strobe lights, CD
ignition systems, etc etc can all generate a crackling, buzzing kind of
static.
And just to cover all bases, look at engine accessories, too. If possible
on the Viking, shut down the alternator. (You should have some form of
control over the alternator, to protect your avionics from an over-voltage
event.) If it has redundant engine controllers, shut off one controller,
then the other, like you would do when doing a mag check on a conventional
a/c engine, to see if one of the controllers is causing the noise.
Something as simple as wiring architecture can also cause noise 'injection'
into the system. If the plane isn't wired with the grounds from potential
noise producers returning to a common point near the battery (meaning that
they use a/c structure as the ground return), then noise produced by the
device can be imposed on the power circuit of other, vulnerable devices,
like the radio and intercom.
Hope that gives you some places to look.
Message 2
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Subject: | Re: Intercom feedback at low rpm |
[quote="ceengland7(at)gmail.com"]On Sun, Jan 14, 2018 at 8:53 PM, Rebel56 wrote:
>
>
> ceengland7(at)gmail.com (http://gmail.com) wrote:
> > On 1/14/2018 8:39 PM, Rebel56 wrote:
> >
> > >
> > >
> > > Been a while since I flew, but I think it could be both, a slight whine,
and static. I can quiet it with the squelch, but doing so also quiets all radio
traffic.
> > > Who were you answering? (Need to quote the person you're replying to, if
> > >
> >
> > there are multiple possibilities.)
> >
> > If it was me, does it change frequency with engine rpm?
> >
> > ---
> > It might change frequency ever so slightly, bu the static is constant and
loud.
> >
>
> If it doesn't change pitch or volume, it would seem to be unrelated to the engine
itself. Have you shed all electrical loads, except the intercom itself? Try
to eliminate every electrical device, to see if the noise stops after dropping
one of them off line. Any device that contains a 'switcher' style power supply
can generate a buzzing noise if it isn't properly filtered. USB power supplies,
both LED & HID lighting, strobe lights, CD ignition systems, etc etc can
all generate a crackling, buzzing kind of static.
>
>
> And just to cover all bases, look at engine accessories, too. If possible on
the Viking, shut down the alternator. (You should have some form of control over
the alternator, to protect your avionics from an over-voltage event.) If it
has redundant engine controllers, shut off one controller, then the other, like
you would do when doing a mag check on a conventional a/c engine, to see if
one of the controllers is causing the noise.
>
>
> Something as simple as wiring architecture can also cause noise 'injection' into
the system. If the plane isn't wired with the grounds from potential noise
producers returning to a common point near the battery (meaning that they use
a/c structure as the ground return), then noise produced by the device can be
imposed on the power circuit of other, vulnerable devices, like the radio and
intercom.
>
>
> Hope that gives you some places to look.
Thanks, all good ideas. When it warms up I will have to start investigating again.
Interesting that nothing on the AC has changed, but the noise just started.
Loose wire maybe.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=477331#477331
Message 3
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Subject: | Re: Intercom feedback at low rpm |
Folks,=0ANot certain I have seen it mentioned, but are all the earths cl
ean and=0Awith minimum resistance.=0ALast time I had an intractable nuis
ance like this, it finally turned=0Aout to be a badly earthed headset (f
emale) plug.=0ACheers,=0ABill Hamilton=0A=0A----- Original Message -----
=0AFrom: avionics-list@matronics.com=0ATo:<avionics-list@matronics.com>
=0ACc:=0ASent:Mon, 15 Jan 2018 15:52:23 -0800=0ASubject:Avionics-List: R
e: Intercom feedback at low rpm=0A=0A --> Avionics-List message posted b
y: "Rebel56" <Rebel56@rogers.com>=0A=0A [quote="ceengland7(at)gmail.co
m"]On Sun, Jan 14, 2018 at 8:53 PM,=0ARebel56 wrote:=0A=0A > --> Avionic
s-List message posted by: "Rebel56" =0A > =0A > =0A > ceengland7(at)gmai
l.com (http://gmail.com) wrote:=0A > > On 1/14/2018 8:39 PM, Rebel56 wro
te:=0A > > =0A > > >=0A > > >=0A > > >=C3=82=C2- Been a while since I
flew, but I think it could be both, a=0Aslight whine, and static. I can
quiet it with the squelch, but doing=0Aso also quiets all radio traffic
.=0A > > > Who were you answering? (Need to quote the person you're=0Are
plying to, if=0A > > >=0A > > =0A > > there are multiple possibilities.)
=0A > > =0A > > If it was me, does it change frequency with engine rpm?
=0A > > =0A > > ---=0A > > It might change frequency ever so slightly, b
u the static is=0Aconstant and loud.=0A > > =0A > =C3=82=C2-=0A > If i
t doesn't change pitch or volume, it would seem to be unrelated=0Ato the
engine itself. Have you shed all electrical loads, except the=0Ainterco
m itself? Try to eliminate every electrical device, to see if=0Athe nois
e stops after dropping one of them off line. Any device that=0Acontains
a 'switcher' style power supply can generate a buzzing noise=0Aif it is
n't properly filtered. USB power supplies, both LED & HID=0Alighting, st
robe lights, CD ignition systems, etc etc can all generate=0Aa crackling
, buzzing kind of static.=0A > =0A > =0A > And just to cover all bases,
look at engine accessories, too. If=0Apossible on the Viking, shut down
the alternator. (You should have=0Asome form of control over the altern
ator, to protect your avionics=0Afrom an over-voltage event.) If it has
redundant engine controllers,=0Ashut off one controller, then the other
, like you would do when doing=0Aa mag check on a conventional a/c engin
e, to see if one of the=0Acontrollers is causing the noise.=0A > =0A >
=0A > Something as simple as wiring architecture can also cause noise
=0A'injection' into the system. If the plane isn't wired with the ground
s=0Afrom potential noise producers returning to a common point near the
=0Abattery (meaning that they use a/c structure as the ground return),
=0Athen noise produced by the device can be imposed on the power circuit
=0Aof other, vulnerable devices, like the radio and intercom.=0A > =0A >
=0A > Hope that gives you some places to look.=0A=0A Thanks, all good i
deas. When it warms up I will have to start=0Ainvestigating again. Inter
esting that nothing on the AC has changed,=0Abut the noise just started.
Loose wire maybe.=0A=0A Read this topic online here:=0A=0A http://forum
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