Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

Intercom wires

Matronics Email Lists Forum Index -> AeroElectric-List

View previous topic :: View next topic

Author Message

cfi(at)conwaycorp.net
Guest

Posted: Wed Jan 09, 2008 5:57 am Post subject: Intercom wires

Hello all.  I  recently purchased a SoftComm 4-place panel mounted intercom that comes with a  pre-wired harness.  I am very  surprised to see that the wires from the audio panel and to the headsets are not  shielded.  Would it be prudent to  replace these wires with shielded ones or will it be ok using them  as-is?    If you're using this product with the harness as  provided, please send me a PIREP. 

  

Thanks! 

<?xml:namespace prefix = o ns =  "urn:schemas-microsoft-com:office:office" />  

Michael 

  

  

  

   [quote][b]

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckolls.bob(at)cox.net
Guest

Posted: Wed Jan 09, 2008 6:51 am Post subject: Intercom wires

At 07:54 AM 1/9/2008 -0600, you wrote:



 	  Quote: 	
		  Hello all.  I recently purchased a SoftComm 4-place panel mounted intercom 

that comes with a pre-wired harness.  I am very surprised to see that the 

wires from the audio panel and to the headsets are not shielded.  Would it 

be prudent to replace these wires with shielded ones or will it be ok 

using them as-is?    If you're using this product with the harness as 

provided, please send me a PIREP.


	




   Virtually all audio system wires in aircraft

   receive 99.99% of their immunity for noise

   propagation by (1) twisting outbound and inbound

   signal return lines and (2) elimination of ground

   loops. Shielding is a prophylactic against

   ELECTROSTATICALLY coupled noises of which there

   are exceedingly few sources and next to none that

   live behind the instrument panel.



   While not a 100% sure deal, suppliers of such

   products will have conducted due diligence in

   crafting the design of their offering . . . while

   working to reduce $time$-out-the-door price of

   their product. Leaving off the shields is low

   risk if (1) and (2) are dutifully satisfied

   and it reduces $time$ required to produce the

   product.



   At the moment, I have no basis for telling you

   that the supplier did a bad thing. Go ahead and

   install it as-is.



   Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

jdubner(at)yahoo.com
Guest

Posted: Wed Jan 09, 2008 7:03 am Post subject: Intercom wires

Michael,



I'm using the two-place version of this intercom and factory harness in

my Long-EZ with no problems.  660 hours/5 years/12V system/IR

alternator/strobes/Lycoming O-235 with 1 magneto and 1 LSE EI.



I can't see shielded wire improving the performance of the earphone

wiring (it's low-impedance and high-level) although I can _imagine_ it

_possibly_ helping for the microphone.  But in practice, all is fine.



If I had an aluminum airplane, I'd be sure to mount the jacks with

insulated shoulder washers to avoid picking up a ground common to other

(noisy) circuits.



Incidentally, Softcomm is one of the "good guys" -- they provided me

with a schematic of their intercom when I  needed to fix it (blown LM386

output IC -- an easy fix).



Best,

Joe

Lewiston, ID

Email: http://mail2600.com/#Contact

On 01/09/2008 05:54 Michael Hinchcliff wrote:

 	  Quote: 	
		   Hello all.  I recently purchased a SoftComm 4-place panel mounted intercom that comes with a pre-wired harness.  I am very surprised to see that the wires from the audio panel and to the headsets are not shielded.  Would it be prudent to replace these wires with shielded ones or will it be ok using them as-is?    If you're using this product with the harness as provided, please send me a PIREP.

 

 

 

 Thanks!

 

  

 

 Michael

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

trigo(at)mail.telepac.pt
Guest

Posted: Wed Jan 09, 2008 10:00 am Post subject: Intercom wires

By the way, Bob



On a broader view of noise protection, let me ask a general (perhaps too

much general) question:



In TC or OBAM aircraft, which of the wires of all used in present electrical

installations must be (or should be) noise protected, and from those which

shall be twisted and which shall be made from shielded wire?

Apart from the ground-loop and careful grounding procedures...



Carlos

[quote] --

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

nuckolls.bob(at)cox.net
Guest

Posted: Fri Jan 11, 2008 7:44 am Post subject: Intercom wires

At 04:54 PM 1/9/2008 +0000, you wrote:



 	  Quote: 	
		  

<trigo(at)mail.telepac.pt>



By the way, Bob



On a broader view of noise protection, let me ask a general (perhaps too

much general) question:



In TC or OBAM aircraft, which of the wires of all used in present electrical

installations must be (or should be) noise protected, and from those which

shall be twisted and which shall be made from shielded wire?

Apart from the ground-loop and careful grounding procedures...



Carlos


	




    Only those called out as shielded in the manufacturer's installation

    instructions. These will be generally limited to strobe head wires,

    p-leads, spark plug wires, and the occasional avionics system signal

    wire.



    The notion here is that nobody knows more than the manufacturer about

    the probability for the device becoming either an antagonist or a victim.



    Having said that, it's not uncommon for a manufacturer to call out

    prophylactic noise mitigation processes that make no sense. I.e.,

    twisting of power wires going into the back of a transceiver. The

    shielding of a power wire coming out of an electronic ignition

    power supply. Shielding the b-lead and field-lead on an alternator

    (I was at Cessna when we crafted that canard!).



    The only risk here is that what ever process is called for is at

    worst the byproduct of someone "whistling-in-the-dark" about noises

    for which there is no demonstrable experiment. On the upside, the

    well crafted system that truly benefits from adding filters or shields

    acquires those recommendations for good reasons.



    Bob . . .

- The Matronics AeroElectric-List Email Forum -

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

Display posts from previous:

	Matronics Email Lists Forum Index -> AeroElectric-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum