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1. 12:23 PM - Shielded wiring (AZFlyer)
2. 04:49 PM - Re: Shielded wiring (FLYaDIVE)
Message 1
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List,
As I am major wiring challenged, I'm reading all the "experts" on getting my 3300
wired. There seems to be one school of thought on "Shielded wiring" that says..."
ground both ends" and another school says only "ground the source end."
or risk a Ground Loop (whatever that is?)
source: Bingelis, Greg Richter, AeroElectric
I haven't located that book " Wiring for Dummies" so, any help would be appreciated...
Thanks,
Mike
--------
Mike Miller @ millrml@aol.com
601 XL-B, 3300, Dynon
Remember, "the second mouse gets the cheese"!
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=312943#312943
Message 2
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| Subject: | Re: Shielded wiring |
Mike:
Here are the RULES for Grounds and Shielding:
1 - GROUNDS - You can't inspect a ground by looking at it... YOU HAVE TO
REMOVE IT... And while it is off clean CLEAN the contacts and replace the
star washers..
2 - GROUNDS - The more the merrier. It took a LONG time but even Bob
Nicholes FINALLY caught on and NOW SELLS multi ground point blocks. I use
to frequent his web site/email list and pounded my case for about a year.
But old wives tails die hard.
3 - GROUNDS - Ground Loops do NOT occur at DC. They are a High
Frequency occurrence - High Frequency is in the RF Range (RF = Radio
Frequency - Transmittable Frequencies)(Not Audio Frequencies... AF). AND I
still have a challenge out that NO ONE has met. MAKE ME A GROUND LOOP DC
CIRCUIT!
4 - SHIELDING - Or in this case: What End of a Shield To Ground?
RF circuits you shield at BOTH ENDS. And lets consider RF as only the
frequencies we see in out planes... VHF.
I know, I know, we all have GPS and they are at microwave frequencies. BUT!
You are not building the units or the antennas, just installing them.
5 - SHIELDING - When you consider things such as Alternator Noise... The
noise is in the audio frequency range and the source is the alternator so
you ground at the source/alternator.
NOW! What happens went the alternator wires reach the ACU/VR (Alternator
Control Unit/Voltage Regulator) and then go out to other locations (ALT
Switch)? Well there the rule stating says ground the source, but what is
the source?
The ACU/VR is the source, But it is already Grounded, usually to the
firewall. SOooooo what do you do with the SHIELD?
You play Electrical Engineer... Not on TV but on your plane. Start with
grounding at the ACU/VR.
But, think ahead and plan ahead. Make a Ground point at the ALT Switch and
put a ring lug on the shield. If you find ALT Noise try grounding at the
ground point you made with the shield near (as close as possible) the ALT
Switch.
It is a GOOD idea to make Ring Lug Grounds on both ends of the shield just
in case the noise did not go to the same school as the electrons. YET! In
all honesty I have never found that to be the case.
6 - Don't forget to install a Capacitor on the OUTPUT of the Alternator B+.
All the shielding in the world won't do dittily if the noise is traveling
out and down your B+.
Barry
On Sun, Sep 19, 2010 at 3:20 PM, AZFlyer <millrML@aol.com> wrote:
>
> List,
>
> As I am major wiring challenged, I'm reading all the "experts" on getting
> my 3300 wired. There seems to be one school of thought on "Shielded wiring"
> that says..." ground both ends" and another school says only "ground the
> source end." or risk a Ground Loop (whatever that is?)
>
> source: Bingelis, Greg Richter, AeroElectric
>
> I haven't located that book " Wiring for Dummies" so, any help would be
> appreciated...
>
> Thanks,
> Mike
>
> --------
> Mike Miller @ millrml@aol.com
> 601 XL-B, 3300, Dynon
>
> Remember, "the second mouse gets the cheese"!
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=312943#312943
>
>
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