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Date: Sat, 9 Jul 2011 15:43:50 -0700
Message-ID: <CAOFHbnrZhn47orcE3xftwq4Fuc7NScLLyyDSp0uCCRXrCQughQ@mail.gmail.com>
Subject: Re: [FlyRotary] Noise in headset when I turn the alternator on
From: David Leonard <wdleonard@gmail.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Content-Type: multipart/alternative; boundary=0015174c34dc208ecb04a7aaafec

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On Sat, Jul 9, 2011 at 7:16 AM, Bill Bradburry <bbradburry@bellsouth.net>wrote:

>    This is not a big problem since I can not hear the hum when in flight,
> but I thought someone might be able to tell me how to stop it.  I have the
> Renesis and I am using the stock capacitor that is attached to the engine.
> When I turn on the alternator, there is a slight buzzing hum that appears in
> the headset and the frequency goes up and down with the engine.  It is
> pretty obviously the alternator I think.****
>
> ** **
>
> Does anyone have any suggestions?****
>
> ** **
>
> Bill B****
>

That is a really common and difficult problem.  I still have an alternator
buzz.  I fly a certified Navion that has a buzz worse than mine.  Almost all
aircraft have it to some extent.  Here are some things to look into and try.

Besides the alternator, look into contributing sources.  For me, it is an
interaction between the alternator and the intercom.  Turn off either
device, and the buzz goes away.  So if I am solo, I can turn off the
intercom.  For me, the buzz through the intercom is only weakly dependent on
intercom volume.  So I can turn down the volume on the headsets and up the
volume on everything else, and it minimizes the buss.

I also got small improvements from each of the following:
Installing an noise choke on the power supply to the intercom.
Turn up the music :-)
Moving the power supply for the alternator field off the main buss (that
included the avionics) into an engine compartment buss near the main
alternator power out.
Using shielded wire for the entire run of the alternator field wire. (to the
switch and back).
But then better than that, I installed a relay near the alternator so that
the field power only travels a short distance and the only connection to the
alternator switch is the trigger for the relay.  That also improved an
alternator over-voltage issue.

I am now to the point where I don't notice the buzz, but if I listen really
hard, it is still there.

-- 
David Leonard

Turbo Rotary RV-6 N4VY
http://N4VY.RotaryRoster.net
http://RotaryRoster.net

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<br><br><div class=3D"gmail_quote">On Sat, Jul 9, 2011 at 7:16 AM, Bill Bra=
dburry <span dir=3D"ltr">&lt;<a href=3D"mailto:bbradburry@bellsouth.net">bb=
radburry@bellsouth.net</a>&gt;</span> wrote:<br><blockquote class=3D"gmail_=
quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1=
ex;">









<div lang=3D"EN-US" link=3D"blue" vlink=3D"purple">

<div>

<div>

<div>

<div>

<p class=3D"MsoNormal"><font size=3D"2" color=3D"navy" face=3D"Arial"><span=
 style=3D"font-size:10.0pt;font-family:Arial;color:navy">This is not a big =
problem since I can not
hear the hum when in flight, but I thought someone might be able to tell me=
 how
to stop it.=A0 I have the Renesis and I am using the stock capacitor that i=
s
attached to the engine.=A0 When I turn on the alternator, there is a slight
buzzing hum that appears in the headset and the frequency goes up and down =
with
the engine.=A0 It is pretty obviously the alternator I think.<u></u><u></u>=
</span></font></p>

<p class=3D"MsoNormal"><font size=3D"2" color=3D"navy" face=3D"Arial"><span=
 style=3D"font-size:10.0pt;font-family:Arial;color:navy"><u></u>=A0<u></u><=
/span></font></p>

<p class=3D"MsoNormal"><font size=3D"2" color=3D"navy" face=3D"Arial"><span=
 style=3D"font-size:10.0pt;font-family:Arial;color:navy">Does anyone have a=
ny suggestions?<u></u><u></u></span></font></p>

<p class=3D"MsoNormal"><font size=3D"2" color=3D"navy" face=3D"Arial"><span=
 style=3D"font-size:10.0pt;font-family:Arial;color:navy"><u></u>=A0<u></u><=
/span></font></p>

<p class=3D"MsoNormal"><font size=3D"2" color=3D"navy" face=3D"Arial"><span=
 style=3D"font-size:10.0pt;font-family:Arial;color:navy">Bill B<u></u><u></=
u></span></font></p>

</div>

</div>

</div>

</div>

</div>


</blockquote></div><br>That is a really common and difficult problem. =A0I =
still have an alternator buzz. =A0I fly a certified Navion that has a buzz =
worse than mine. =A0Almost all aircraft have it to some extent. =A0Here are=
 some things to look into and try.<div>
<br></div><div>Besides the=A0alternator, look into=A0contributing=A0sources=
. =A0For me, it is an interaction between the alternator and the intercom. =
=A0Turn off either device, and the buzz goes away. =A0So if I am solo, I ca=
n turn off the intercom. =A0For me, the buzz=A0through=A0the intercom is on=
ly weakly dependent on intercom volume. =A0So I can turn down the volume on=
 the headsets and up the volume on everything else, and it minimizes the bu=
ss.</div>
<div><br></div><div>I also got small improvements from each of the followin=
g:</div><div>Installing an noise choke on the power supply to the intercom.=
</div><div>Turn up the music :-)</div><div>Moving the power supply for the =
alternator field off the main buss (that included the avionics) into an eng=
ine compartment buss near the main alternator power out.</div>
<div>Using shielded wire for the entire run of the alternator field wire. (=
to the switch and back).</div><div>But then better than that, I installed a=
 relay near the alternator so that the field power only travels a short dis=
tance and the only connection to the alternator switch is the trigger for t=
he relay. =A0That also=A0improved=A0an alternator over-voltage issue.</div>
<div><br></div><div>I am now to the point where I don&#39;t notice the buzz=
, but if I listen really hard, it is still there.<br clear=3D"all"><br>-- <=
br>David Leonard<br><br>Turbo Rotary RV-6 N4VY<br><a href=3D"http://N4VY.Ro=
taryRoster.net">http://N4VY.RotaryRoster.net</a><br>
<a href=3D"http://RotaryRoster.net">http://RotaryRoster.net</a><br>
</div>

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