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Date: Wed, 05 Sep 2012 12:28:42 -0400
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Subject: Re: [LML] Re: Probes gone wild
References: <list-5744429@logan.com>
From: J H Webb <airmale4@yahoo.com>
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Sounds like the problem I have had, but filling the tank & burning it down a=
 couple of times fixes it. I don't have any proof but on a test program we h=
ad in the past, humidity would form in the probe above the fuel and reduce t=
he accuracy. I am suspicious this is what is happening here occasionally.=20=


Jack Webb
L360, LIV
Formally Chief GA Engineering Test Pilot

Sent from my iPad

On Sep 4, 2012, at 23:16, Colyn Case <colyncase@earthlink.net> wrote:

> Adam, are you measuring that right at the probe or is there something in t=
he middle?
> I have not had anything like this occur with my EI probes.   I did however=
 have a lot of problems with the previous (old) princeton converters.   If m=
emory serves, these convert from freq to 0-5V.   The new 10-point Princeton c=
onverters have been great.
>=20
>=20
> On Sep 4, 2012, at 4:18 PM, <marv@lancair.net> <marv@lancair.net> wrote:
>=20
>=20
> Posted for Adam Molny <Adam@ValidationPartners.com>:
>=20
> My EI fuel probes output a square wave whose frequency is proportional to
> fuel level. Before installation, bench testing showed that the probes put
> out 4kHz when dry and 2kHz when full. I calibrated my Dynon SkyView
> accordingly. Now, at 70 hours the left probe has become unreliable. A few
> weeks ago the frequencies changed to 3kHz empty and 2kHz full. I calibrate=
d
> the Dynon, but now the probe is putting out 3kHz when full.
>=20
> Has anyone had similar problems? I'll have to remove the left wing to get
> the probe out, so I'd like to have a plan of action first.=20
>=20
> Thanks,
> Adam Molny
>  Legacy N181AM=20
>  72 hours hobbs time
>=20
>=20
> [We have an EI capacitive probe on our test stand and noticed that it is s=
ubject to large swings relative to temperature.  Not the probe itself, but r=
ather the oscillator module whose frequency is driven by the probe.  The eas=
iest way for me to fill our 280 gallon tank is to pull the truck out into th=
e Florida sunshine and expose the oscillator to full sunlight... soon as it h=
eats up the tank tops itself right off... damnedest thing you ever saw.  Onl=
y problem is it won't stay full.   <Marv>   ]
>=20
>=20
> --
>=20
> For archives and unsub http://mail.lancaironline.net:81/lists/lml/List.htm=
l
>=20
>=20
>=20
> 
>=20
> =20
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<html><head></head><body bgcolor=3D=22=23FFFFFF=22><div>Sounds like the =
problem I have had, but filling the tank &amp; burning it down a couple of =
times fixes it. I don't have any proof but on a test program we had in the =
past, humidity would form in the probe above the fuel and reduce the =
accuracy. I am suspicious this is what is happening here =
occasionally.&nbsp;</div><div><br></div><div>Jack Webb</div><div>L360, =
LIV</div><div>Formally Chief GA Engineering Test Pilot<br><br>Sent from my =
iPad</div><div><br>On Sep 4, 2012, at 23:16, Colyn Case &lt;<a =
href=3D=22mailto:colyncase=40earthlink.net=22>colyncase=40earthlink.net</a>=
&gt; wrote:<br><br></div><div></div><blockquote =
type=3D=22cite=22><div>Adam, are you measuring that right at the probe or =
is there something in the middle?<div>I have not had anything like this =
occur with my EI probes. &nbsp; I did however have a lot of problems with =
the previous (old) princeton converters. &nbsp; If memory serves, these =
convert from freq to 0-5V. &nbsp; The new 10-point Princeton converters =
have been great.</div><div><br></div><div><br><div><div>On Sep 4, 2012, at =
4:18 PM, &lt;<a =
href=3D=22mailto:marv=40lancair.net=22>marv=40lancair.net</a>&gt; &lt;<a =
href=3D=22mailto:marv=40lancair.net=22>marv=40lancair.net</a>&gt; =
wrote:</div><br class=3D=22Apple-interchange-newline=22><div =
id=3D=22_htmlarea_default_style_=22 style=3D=22font:10pt =
arial,helvetica,sans-serif=22><br>Posted for Adam Molny &lt;<a =
href=3D=22mailto:Adam=40ValidationPartners.com=22>Adam=40ValidationPartners=
=2Ecom</a>&gt;:<br><br>
My EI fuel probes output a square wave whose frequency is proportional =
to<br> fuel level. Before installation, bench testing showed that the probes
put<br> out 4kHz when dry and 2kHz when full. I calibrated my Dynon =
SkyView<br> accordingly. Now, at 70 hours the left probe has become =
unreliable. A
few<br> weeks ago the frequencies changed to 3kHz empty and 2kHz full. I =
calibrated<br> the Dynon, but now the probe is putting out 3kHz when
full.<br>  <br><div align=3D=22left=22>Has anyone had similar problems? =
I'll have to remove the left wing to get<br> the probe out, so I'd like to =
have a
plan of action first. <br> <br>Thanks,<br> Adam Molny<br> &nbsp;Legacy =
N181AM <br> &nbsp;72 hours hobbs time<br> <br><div =
align=3D=22left=22><br></div></div><div align=3D=22left=22>=5BWe have an =
EI capacitive probe on our test stand and noticed that it is subject to =
large swings
relative to temperature. &nbsp;Not the probe itself, but rather the =
oscillator module whose frequency is driven by the probe. &nbsp;The =
easiest way
for me to fill our 280 gallon tank is to pull the truck out into the =
Florida sunshine and expose the oscillator to full sunlight... soon as it =
heats
up the tank tops itself right off... damnedest thing you ever saw. =
&nbsp;Only problem is it won't stay full. &nbsp; &lt;Marv&gt; &nbsp; =
=5D</div><div align=3D=22left=22><br></div></div><div><br =
class=3D=22webkit-block-placeholder=22></div><pre>--

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</div><br></div></div></blockquote></body></html>=
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