Today's Message Index:
----------------------
1. 02:08 AM - Re: TWISTED PAIRS (John M Tipton)
2. 02:11 AM - Re: TWISTED PAIRS (John M Tipton)
3. 02:30 AM - Re: TWISTED PAIRS (user9253)
4. 06:06 AM - Re: TWISTED PAIRS (Robert L. Nuckolls, III)
5. 06:26 AM - Re: Re: TWISTED PAIRS (Robert L. Nuckolls, III)
6. 07:19 AM - Re: TWISTED PAIRS (Ernest Christley)
7. 07:54 AM - Re: TWISTED PAIRS (Robert L. Nuckolls, III)
8. 11:33 AM - Re: ovm (skywagon185guy)
9. 05:08 PM - GRT EIS Issues When Transmitting ()
10. 05:11 PM - Re: ovm (Robert L. Nuckolls, III)
11. 05:47 PM - Re: ovm (Charlie England)
12. 05:58 PM - Re: TWISTED PAIRS (Art Zemon)
Message 1
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| Subject: | Re: TWISTED PAIRS |
Hi Bob
Here is an example of twisted pairs (even twisted trio) you asked for my EZpilot
(A/p):
file:///C:/Users/John%20Tipton/Downloads/EZ%20Pilot%20Manual%20rev%202.5%20.pdf
I hope that works and it on page 36:
Regards
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=489049#489049
Message 2
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| Subject: | Re: TWISTED PAIRS |
Hi Bob
Try this:
https://www.trioavionics.com/EZ%20Pilot%20Manual%20rev%202.5%20.pdf
Page 36
John
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=489050#489050
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| Subject: | Re: TWISTED PAIRS |
John,
The link that you posted points to a file on your hard drive.
Below is a link to the EZ Pilot Operation and Installation Manual on Trio Avionics
website:
https://www.trioavionics.com/EZ%20Pilot%20Manual%20rev%202.5%20.pdf
--------
Joe Gores
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=489051#489051
Message 4
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At 06:18 PM 5/1/2019, you wrote:
>
>Doesn't the remote panel switch for ELTs generally specify the use of
>twisted-pair wiring? Seems like I recall seeing that when I was
>considering replacing my ELT.
Could be . . . and I too have suggested it for situations
where one is building a long run of 2 or more wires. I've
often used a drill motor to build an independent bundle
of wires, usually small (22 or 20AWG max) that all terminated
in the same place.
Twisting is, at best, a matter of craftsmanship/convenience.
A bundle of wires in a 'straight lay' is stiff while
a twisted array remains flexible while physically
constrained in a handy bundle. When building pendant
cables for ground test equipment, I often twist the
array of wires before pulling them through a 'snake
skin' . . . makes for a really compliant test tool.
Mitigation of magnetic/electro-static coupling by twisting
SEEMS like a good idea . . . except that those coupling
modes are exceedingly weak and practical ONLY when the
pair to be twisting is either a STRONG potential antagonist
or VULNERABLE victim.
The DC power leads are NOT potential antagonists
nor are they vulnerable.
The fact that either of these conditions
is a consideration for integrating a particular
electro-whizzy into your airplane is a CONFESSION
of poor attention to details . . . like Mil-Std-704,
DO-160, etc . . . or a lack of understanding.
It's like the ol' avionics master switch meme intended
to ward off evil, non-existent 'spikes' while cranking
an engine. Once planted, it will grow and thrive like
an intellectual fungus long after advances in understanding
and application of the SCIENCE has shown it to be floobydust.
The short answer is: when your electro-whizzy's installation
manual calls for twisting for 'noise' or avionics master switch
for 'spikes', a healthy dose of skepticism is called for.
Bob . . .
Message 5
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| Subject: | Re: TWISTED PAIRS |
At 04:07 AM 5/2/2019, you wrote:
>
>Hi Bob
>
>Here is an example of twisted pairs (even twisted trio) you asked
>for my EZpilot (A/p):
>
>file:///C:/Users/John%20Tipton/Downloads/EZ%20Pilot%20Manual%20rev%202.5%20.pdf
>
>I hope that works and it on page 36:
The folks who wrote this did a better
than average job, but their lack of
experience in air-frame wiring is
obvious.
The narrative about wire sizes is
startling. 24AWG wire in an airframe
is more difficult to work with . . .
26AWG would NOT be recommended.
I would not suggest such a thing for
OBAM aircraft and would think LONG
and HARD before calling it out in
a TC aircraft.
Premier (B390) airframe wiring used
a lot of 24 . . . but this was a 'busy'
airplane with miles of wire in it.
Weight savings was significant. But
the people who had to work with it
on the line and in the field were
less than enthusiastic.
Our airplanes (with mere dozens of
feet of wire), hooking up with
smaller than 22AWG is of no practical
benefit.
The shielded trios use to wire the
servos is handy from a fabrication/
installation perspective. The
EMC considerations for using
a shielded trio may be (but
unlikely) valid. But using off-
the-spool, pre-twisted, pre-twisted,
shielded wire is very convenient.
Bob . . .
Message 6
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| Subject: | Re: TWISTED PAIRS |
I like to twist power and ground for organizational reasons.=C2- It just
cleans up the installation.
On Wednesday, May 1, 2019, 5:38:13 PM EDT, Robert L. Nuckolls, III <nuc
kolls.bob@aeroelectric.com> wrote:
At 10:43 AM 5/1/2019, you wrote:
--> AeroElectric-List messageposted by: "John M Tipton" <john@tiptonuk.eu>
Hi Guys (Bob)
When a twisted pair is required (eg: Power and ground to Radio), do youtake
both back to the fuse panel, then lead off the ground wire to theground bl
ock=C2- ( which is a return route - L form) or lead off theground wire to
the ground block en route (it's only half distance to theground block - ie
: T form)
To clarify: the route to the ground block is 15 inches and to the Fusebus 3
0 inches.
=C2- I can't imagine why anyone would twist
=C2- the ground and power wires on any device
=C2- (other than the illumination lamp to a
=C2- whisky compass up on the windshield).
=C2- What's the product and what, if any, reason
=C2- is given in instructions for doing this
=C2- to the wires?
=C2- Bob . . .
Message 7
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| Subject: | Re: TWISTED PAIRS |
At 09:18 AM 5/2/2019, you wrote:
>I like to twist power and ground for organizational reasons. It
>just cleans up the installation.
Hear hear!
Bob . . .
Message 8
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Only an assumption, but, I would think that the ovm trip setting should be
lower than 16.2 vdc.
Maybe in the 15 volt range.
It would be great if someone with battery experience details would chime in
on how high the charge voltage rate can go before starting to "cook" our
aviation type batteries.
On Wed, May 1, 2019 at 5:00 AM bobnoffs <icubob@gmail.com> wrote:
>
> hi all,
> the past 6 months i have spent time looking into ovm's. i have just
> completed installation and tested one from perihelion. as the ad says
> 'about the size of a domino'. it actuates a relay on the output of my
> alternator. instructions and schematics were excellent and eric [owner] was
> very helpful.
> very simple. at 16.2 volts this unit opens the circuit to the relay coil
> and lights up an led on the panel.
> bob noffs
>
>
> Read this topic online here:
>
> http://forums.matronics.com/viewtopic.php?p=489034#489034
>
>
Message 9
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| Subject: | GRT EIS Issues When Transmitting |
Greeting,
I am posting for a friend who fly a Velocityand I will get him
to sign up for the Aeroelectric.
His Question:
I need help with further troubleshooting an anomaly. When I key the
radio, all EGT & CHT temps drop about 25 degrees and stay there until
the transmission is released at which time they return to normal. This
is repeatable with the engine running or not. The EIS has been replaced
with a brand new one. I have swapped radios on the antenna. Whichever
radio is using the stbd antenna causes the anomaly. I inspected the
antenna wire (RG-400) as much as possible without removing it. No wear
or nicks. System, both EIS and radios have been flawless since
installation in 2016. Have even installed a ferrite sleeve on the
cht/egt wire bundle. No change. Transmission and reception on the radio
is loud and clear.
I have a GRT EIS mounted [at the back of the copilot side of the
airplane] on the floor. The wires run through the [fiberglass conduit]
to the engine.
The closest the antenna gets to the EIS is about 18 inches.
Thanks,
Bill Hunter
Message 10
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At 01:32 PM 5/2/2019, you wrote:
>Only an assumption, but, I would think that the
>ovm trip setting should be lower than 16.2 vdc.
>Maybe in the 15 volt range.
>It would be great if someone with battery
>experience details would chime in on how high
>the charge voltage rate can go before starting
>to "cook"=C2 our aviation type=C2 batteries.
First of all, OV conditions are first of all rare.
Second, they almost never present a 'creeping rise' in
bus voltage. OV regulation failures tend to be
gross over excitation events that cause an
alternator to deliver a constant current
(slightly higher than its nameplate rating)
with no practical limit to the limit to
the alternator's UNLOADED output.
The key word is UNLOADED . . . there are
ship's accessories on line . . . then there's
a battery that will attempt to absorb what
energy is left over between alternator ratings
and ship's loads.
Hence, the voltage doesn't 'creep', rather
it will rise at some observable rate over
a period of seconds to perhaps a couple of
minutes. OV protection systems are generally
designed to trip for any ov condition that
exceeds 16.0 (32.0) volts for something
on the order of 500 milliseconds (The
DO-160 stand off value for 20.0/40.0v is
1.0 second).
In the exceedingly rare case that your
regulator decides to do the creepy thing,
it will no doubt be so slow that you'll
easily know that something is amiss from
observation of ship's various voltage
displays.
So, Eric's selected calibration point for
ov trip is consistent with legacy
design goals and very conservative in
light of DO-160 qualification protocols
along with alternator/battery performance under
demonstrated ov stress.
Bob . . .
Message 11
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On 5/2/2019 7:11 PM, Robert L. Nuckolls, III wrote:
> At 01:32 PM 5/2/2019, you wrote:
>> Only an assumption, but, I would think that the ovm trip setting
>> should be lower than 16.2 vdc.
>> Maybe in the 15 volt range.
>> It would be great if someone with battery experience details would
>> chime in on how high the charge voltage rate can go before starting
>> to "cook" our aviation type batteries.
>
> First of all, OV conditions are first of all rare.
> Second, they almost never present a 'creeping rise' in
> bus voltage. OV regulation failures tend to be
> gross over excitation events that cause an
> alternator to deliver a constant current
> (slightly higher than its nameplate rating)
> with no practical limit to the limit to
> the alternator's UNLOADED output.
>
> The key word is UNLOADED . . . there are
> ship's accessories on line . . . then there's
> a battery that will attempt to absorb what
> energy is left over between alternator ratings
> and ship's loads.
>
> Hence, the voltage doesn't 'creep', rather
> it will rise at some observable rate over
> a period of seconds to perhaps a couple of
> minutes. OV protection systems are generally
> designed to trip for any ov condition that
> exceeds 16.0 (32.0) volts for something
> on the order of 500 milliseconds */(The
> DO-160 stand off value for 20.0/40.0v is
> 1.0 second).
>
> /* In the exceedingly rare case that your
> regulator decides to do the creepy thing,
> it will no doubt be so slow that you'll
> easily know that something is amiss from
> observation of ship's various voltage
> displays.
>
> So, Eric's selected calibration point for
> ov trip is consistent with legacy
> design goals and very conservative in
> light of DO-160 qualification protocols
> along with alternator/battery performance under
> demonstrated ov stress.
>
>
> Bob . . .
>
And, if you assume that with a 'modern' panel, the engine monitor will
have configurable voltage limits for its alarm circuitry, you can set
the hi V alarm point right at the battery's max allowable, get notified
if that happening, and avoid nuisance trips by the OVM.
---
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Message 12
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| Subject: | Re: TWISTED PAIRS |
I didn't twist much of anything. I used red and black wire and laced the
bundles. It ended up looking nice and the lacing was peaceful, satisfying
work.
I did twist the wires for my OAT probe and that was just to make the pair
easier to handle since it runs the length of the fuselage.
-- Art Z.
Sent from my phone. Please excuse brevity and bizarre typos.
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