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Date: Tue, 14 May 2013 11:46:01 -0400
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From: Gary Casey <casey.gary@yahoo.com>
Reply-To: Gary Casey <casey.gary@yahoo.com>
Subject: Re: Electronics International divide-by-4 (/4)
In-Reply-To: <listdigest-6269275@logan.com>
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Can't fail?=A0 Well, the probe itself is a tube with a central rod that mak=
es up a capacitor.=A0 If something conductive gets in between it could shor=
t and cause a failure.=A0 Or the termination at the wire could go open.=A0 =
That's not counting the electronics that converts the capacitance to a freq=
uency.=A0 How to test?=A0 The only way I know of is to get a small capacito=
r and connect it from the central rod to the shell (without touching anythi=
ng yourself - not easy).=A0 I've forgotten what the likely value should be,=
 but a 100pf should at least make a movement and a 0.1mfd might be more tha=
n full scale.=A0 You might have to experiment a little.=A0 Then look at the=
 output.=A0 I think EI puts a simple cap-frequency converter in the probe i=
tself, so you have to read the frequency with a scope.=A0 Not the kind of t=
est that can be done in the average garage, but it's not that complicated e=
ither.=0AGary=0A=A0=0A=A0=0A=0AEII says probes can't fail.=0A=0ASent using =
my iPhone.=0ADanny=0A=0AOn May 13, 2013, at 12:31 PM, "William A. Hogarty" =
<billhogarty@gmail.com> w=3D=0Arote:=0A=0A> Does anyone know a method to te=
st a VM probe in the wing when the wing has=3D=0Abeen removed from the ,pla=
ne.
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<html><body><div style=3D"color:#000; background-color:#fff; font-family:bo=
okman old style, new york, times, serif;font-size:12pt"><div>Can't fail?&nb=
sp; Well, the probe itself is a tube with a central rod that makes up a cap=
acitor.&nbsp; If something conductive gets in between it could short and ca=
use a failure.&nbsp; Or the termination at the wire could go open.&nbsp; Th=
at's not counting the electronics that converts the capacitance to a freque=
ncy.&nbsp; How to test?&nbsp; The only way I know of is to get a small capa=
citor and connect it from the central rod to the shell (without touching an=
ything yourself - not easy).&nbsp; I've forgotten what the likely value sho=
uld be, but a 100pf should at least make a movement and a 0.1mfd might be m=
ore than full scale.&nbsp; You might have to experiment a little.&nbsp; The=
n look at the output.&nbsp; I think EI puts a simple cap-frequency converte=
r in the probe itself, so you have to read the frequency with a
 scope.&nbsp; Not the kind of test that can be done in the average garage, =
but it's not that complicated either.</div><div>Gary</div><div>&nbsp;</div>=
<div>&nbsp;<br><br>EII says probes can't fail.<br><br>Sent using my iPhone.=
<br>Danny<br><br>On May 13, 2013, at 12:31 PM, "William A. Hogarty" &lt;<a =
href=3D"mailto:billhogarty@gmail.com" ymailto=3D"mailto:billhogarty@gmail.c=
om"><font color=3D"#2862c5">billhogarty@gmail.com</font></a>&gt; w=3D<br>ro=
te:<br><br>&gt; Does anyone know a method to test a VM probe in the wing wh=
en the wing has=3D<br> been removed from the ,plane.</div></div></body></ht=
ml>
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