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Radio shields

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djones(at)northboone.net
Guest

Posted: Wed Sep 13, 2006 9:21 am Post subject: Radio shields

I’m wiring the harness for a Terra TX-760D radio. My question is the interconnect diagram shows the shield for the mic. audio, mic. key and the headphone attach to the ground. I plan on using the daisy chain system shown by Bob, however I’m confused about the shields connecting into the ground wire itself or do they connect to the shield of the ground wire?  

   

Dennis  

        [quote][b]

brian-av(at)lloyd.com
Guest

Posted: Wed Sep 13, 2006 1:16 pm Post subject: Radio shields

rOn Wed, 2006-09-13 at 10:12, Dennis Jones wrote:

 	  Quote: 	
		   I?m wiring the harness for a Terra TX-760D radio. My question is the

 interconnect diagram shows the shield for the mic. audio, mic. key and

 the headphone attach to the ground. I plan on using the daisy chain

 system shown by Bob, however I?m confused about the shields connecting

 into the ground wire itself or do they connect to the shield of the

 ground wire?


	


If the radio itself has separate sheild and ground connections (most

don't) then you would connect the shield and ground to their respective

connections. Most radios just have a ground connection so both the

shield and the ground wire (if they are separate) should connect to the

ground pin(s) at the radio.



Normally I would run separate wire for mic/ptt and headphone. Speaking

specifically of the mic/ptt wiring, you can use the shield of the mic

cable as your mic and ptt ground wiring if you wish. If your mic wiring

has three conductors plus shield, I would probably use one conductor for

ground and then not attach anything to the shield (except at the radio).



If you are using an intercom you will probably have separate mic/ptt

wiring for each mic jack. (Most intercoms provide mic isolation when you

hit the PTT for one mic, the other mics are muted to keep noise from

getting into the transmit audio.) 



If you are not using an intercom then you may daisy-chain your mic and

PTT connections. Just continue ground, shield, PTT, and mic hot.



Whatever you choose to do be sure you insulate the mic jacks from the

airframe.



Headphone wiring does not need to be shielded. I would use twisted pair.

You can get away with using airframe ground for the ground side of your

headphone but you are more likely to get some noise pick-up. This may

become objectionable if you are trying to have high-fidelity audio. Best

to insulate the headphone jacks as well.



Brian Lloyd

nuckollsr(at)cox.net
Guest

Posted: Wed Sep 13, 2006 3:22 pm Post subject: Radio shields

At 12:12 PM 9/13/2006 -0500, you wrote:



 	  Quote: 	
		  I m wiring the harness for a Terra TX-760D radio. My question is the 

interconnect diagram shows the shield for the mic. audio, mic. key and the 

headphone attach to the ground. I plan on using the daisy chain system 

shown by Bob, however I m confused about the shields connecting into the 

ground wire itself or do they connect to the shield of the ground wire?


	


  Can you scan the wiring from the instruction manual

  and send it to me?



  It would be useful to see how they've depicted their

  suggestions for the installation.



  Bob . . .



      ---------------------------------------------------------

      < What is so wonderful about scientific truth...is that >

      < the authority which determines whether there can be   >

      < debate or not does not reside in some fraternity of   >

      < scientists; nor is it divine. The authority rests     >

      < with experiment.                                      >

      <                            --Lawrence M. Krauss       >

      ---------------------------------------------------------

nuckollsr(at)cox.net
Guest

Posted: Thu Sep 14, 2006 10:48 am Post subject: Radio shields

At 06:21 PM 9/13/2006 -0500, you wrote:

 	  Quote: 	

<nuckollsr(at)cox.net>

At 12:12 PM 9/13/2006 -0500, you wrote:

>I m wiring the harness for a Terra TX-760D radio. My question is the 

>interconnect diagram shows the shield for the mic. audio, mic. key and 

>the headphone attach to the ground. I plan on using the daisy chain 

>system shown by Bob, however I m confused about the shields connecting 

>into the ground wire itself or do they connect to the shield of the 

>ground wire?

  Can you scan the wiring from the instruction manual

  and send it to me?

  It would be useful to see how they've depicted their

  suggestions for the installation.

   Okay, got the scans. Great.

   I guess I'm not sure what the question is. The schematic shows

   two aircraft ground (A/C Ground) connections to pins 4 and 15.

   Wires that the manufacturer recommends be shielded have their

   shield grounds returned to specific pins. They also show how

   the shield can double as a ground return for mic, headphone,

   speaker leads, etc. Further, their wiring suggests exactly

   the same daisy-chaining technique I described in:

http://aeroelectric.com/articles/pigtail/pigtail.html

   OOPS!  I just re-read your question and I think missed

   something the first time. You talk about a "shield of

   the ground wire".

   The drawings show single strands of wire from pins 4 and

   15 to ground. Your pigtails would either solder onto the

   shared solder cups or splice into the ground wires immediately

   adjacent to where they drop into the crimped on pin pocket.

   The ground wires are not shielded.

   Bob . . .

djones(at)northboone.net
Guest

Posted: Thu Sep 14, 2006 1:15 pm Post subject: Radio shields

Thanks Bob

If one solders the wire to the cup, would the pig tail solder literally 

onto the

side of the cup or in the cup and would you join the wires first? If I splice

the wires using the pin pocket what would be the best way to splice the wires

together prior to installing into the pocket, i.e. wrapped, soldered?

Dennis

Quoting "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>:

 	  Quote: 	

 <nuckollsr(at)cox.net>

 At 06:21 PM 9/13/2006 -0500, you wrote:

> 

> <nuckollsr(at)cox.net>

>

> At 12:12 PM 9/13/2006 -0500, you wrote:

>

>> I m wiring the harness for a Terra TX-760D radio. My question is 

>> the interconnect diagram shows the shield for the mic. audio, mic. 

>> key and the headphone attach to the ground. I plan on using the 

>> daisy chain system shown by Bob, however I m confused about the 

>> shields connecting into the ground wire itself or do they connect 

>> to the shield of the ground wire?

>

>  Can you scan the wiring from the instruction manual

>  and send it to me?

>

>  It would be useful to see how they've depicted their

>  suggestions for the installation.

   Okay, got the scans. Great.

   I guess I'm not sure what the question is. The schematic shows

   two aircraft ground (A/C Ground) connections to pins 4 and 15.

   Wires that the manufacturer recommends be shielded have their

   shield grounds returned to specific pins. They also show how

   the shield can double as a ground return for mic, headphone,

   speaker leads, etc. Further, their wiring suggests exactly

   the same daisy-chaining technique I described in:

 http://aeroelectric.com/articles/pigtail/pigtail.html

   OOPS!  I just re-read your question and I think missed

   something the first time. You talk about a "shield of

   the ground wire".

   The drawings show single strands of wire from pins 4 and

   15 to ground. Your pigtails would either solder onto the

   shared solder cups or splice into the ground wires immediately

   adjacent to where they drop into the crimped on pin pocket.

   The ground wires are not shielded.

   Bob . . .

djones(at)northboone.net
Guest

Posted: Thu Sep 14, 2006 1:27 pm Post subject: Radio shields

Bob

When you speak of the "shield grounds return to specific pins" are you talking

about pins 4 and 15? The shield doubling as a ground return are you 

refering to

the shield attaching to the mic and headphone jack lugs?

Dennis

Quoting "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>:

 	  Quote: 	

 <nuckollsr(at)cox.net>

 At 06:21 PM 9/13/2006 -0500, you wrote:

> 

> <nuckollsr(at)cox.net>

>

> At 12:12 PM 9/13/2006 -0500, you wrote:

>

>> I m wiring the harness for a Terra TX-760D radio. My question is 

>> the interconnect diagram shows the shield for the mic. audio, mic. 

>> key and the headphone attach to the ground. I plan on using the 

>> daisy chain system shown by Bob, however I m confused about the 

>> shields connecting into the ground wire itself or do they connect 

>> to the shield of the ground wire?

>

>  Can you scan the wiring from the instruction manual

>  and send it to me?

>

>  It would be useful to see how they've depicted their

>  suggestions for the installation.

   Okay, got the scans. Great.

   I guess I'm not sure what the question is. The schematic shows

   two aircraft ground (A/C Ground) connections to pins 4 and 15.

   Wires that the manufacturer recommends be shielded have their

   shield grounds returned to specific pins. They also show how

   the shield can double as a ground return for mic, headphone,

   speaker leads, etc. Further, their wiring suggests exactly

   the same daisy-chaining technique I described in:

 http://aeroelectric.com/articles/pigtail/pigtail.html

   OOPS!  I just re-read your question and I think missed

   something the first time. You talk about a "shield of

   the ground wire".

   The drawings show single strands of wire from pins 4 and

   15 to ground. Your pigtails would either solder onto the

   shared solder cups or splice into the ground wires immediately

   adjacent to where they drop into the crimped on pin pocket.

   The ground wires are not shielded.

   Bob . . .

nuckollsr(at)cox.net
Guest

Posted: Thu Sep 14, 2006 2:57 pm Post subject: Radio shields

At 04:26 PM 9/14/2006 -0500, you wrote:



 	  Quote: 	
		  



Bob



When you speak of the "shield grounds return to specific pins" are you talking

about pins 4 and 15?


	


   Yes . . . the schematic clearly shows that both shield grounds -and-

   power grounds to airframe connect to pins 15 and 4.



 	  Quote: 	
		    The shield doubling as a ground return are you refering to

the shield attaching to the mic and headphone jack lugs?


	


   Yes . . . the outer shield braid doubles as electrostatic

   shield -AND- signal ground for the remote components.



   This is a common technique. I use it several places in

   the wiring diagrams shown in.



http://www.aeroelectric.com/Catalog/AEC/9009/9009-700J.pdf



   Bob . . .

nuckollsr(at)cox.net
Guest

Posted: Thu Sep 14, 2006 3:00 pm Post subject: Radio shields

At 04:14 PM 9/14/2006 -0500, you wrote:



 	  Quote: 	
		  



Thanks Bob



If one solders the wire to the cup, would the pig tail solder literally 

onto the

side of the cup or in the cup and would you join the wires first? If I splice

the wires using the pin pocket what would be the best way to splice the wires

together prior to installing into the pocket, i.e. wrapped, soldered?


	


   The cups are obviously too small to accept a pair of wires.

   I usually tack solder the shield pigtails to the side of the

   cup after the main wire is installed inside the cup.



   For crimped pins, I'd probably include the airframe ground wires

   into the inner-most cluster of the daisy chain so that shields

   and ground wire all come together at the end of the shielded wire.

   Then, the pigtail for the shields can do double duty and crimp

   into the d-sub pin.



   Bob . . .

djones(at)northboone.net
Guest

Posted: Thu Sep 14, 2006 5:52 pm Post subject: Radio shields

For crimped pins with the ground wires as the inermost wouldn't the 

pigtail and

ground wire ends come together and then crimp into the d-sub pin.



Dennis



Quoting "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>:



 	  Quote: 	
		   

 <nuckollsr(at)cox.net>



 At 04:14 PM 9/14/2006 -0500, you wrote:



> 

>

> Thanks Bob

>

> If one solders the wire to the cup, would the pig tail solder 

> literally onto the

> side of the cup or in the cup and would you join the wires first? If 

> I splice

> the wires using the pin pocket what would be the best way to splice 

> the wires

> together prior to installing into the pocket, i.e. wrapped, soldered?



   The cups are obviously too small to accept a pair of wires.

   I usually tack solder the shield pigtails to the side of the

   cup after the main wire is installed inside the cup.



   For crimped pins, I'd probably include the airframe ground wires

   into the inner-most cluster of the daisy chain so that shields

   and ground wire all come together at the end of the shielded wire.

   Then, the pigtail for the shields can do double duty and crimp

   into the d-sub pin.



   Bob . . .

nuckollsr(at)cox.net
Guest

Posted: Fri Sep 15, 2006 2:16 am Post subject: Radio shields

At 08:51 PM 9/14/2006 -0500, you wrote:



 	  Quote: 	
		  



For crimped pins with the ground wires as the inermost wouldn't the 

pigtail and

ground wire ends come together and then crimp into the d-sub pin.



Dennis


	


  Shielded ground wires? Don't know why anyone would do that.

  Grounded wires are, by definition, immune to the effects

  of electrostatic noise coupling.



  Two classes of wiring benefit from the addition of shielding

  (which is grounded at least at one end).



   (1) wires that carry strong potentially antagonistic

       signals (high voltage, fast risetime waveforms).

       Magneto p-leads are always worth shielding unless

       you're building a day vfr machine with no radios.



   (2) wires that carry small, potentially victim signals

       (low voltages that carry intelligence in the form

       of voice, data or display signals). These will be

       circuits like microphones and small signal lines

       between various black boxes of a system.



       Wires that are used for grounding do no fall into

       either of these categories.



  Bob . . .

djones(at)northboone.net
Guest

Posted: Fri Sep 15, 2006 9:25 am Post subject: Radio shields

Bob



I was refering to the schematic for the Terra radios where the phone and mic

jack shielded wires come into the radio and the shield of those wires are tied

into the ground wire going into the radio using the daisy chain system and the

pig tail attaches to the ground.



Dennis



Quoting "Robert L. Nuckolls, III" <nuckollsr(at)cox.net>:



 	  Quote: 	
		   

 <nuckollsr(at)cox.net>



 At 08:51 PM 9/14/2006 -0500, you wrote:



> 

>

> For crimped pins with the ground wires as the inermost wouldn't the 

> pigtail and

> ground wire ends come together and then crimp into the d-sub pin.

>

> Dennis



  Shielded ground wires? Don't know why anyone would do that.

  Grounded wires are, by definition, immune to the effects

  of electrostatic noise coupling.



  Two classes of wiring benefit from the addition of shielding

  (which is grounded at least at one end).



   (1) wires that carry strong potentially antagonistic

       signals (high voltage, fast risetime waveforms).

       Magneto p-leads are always worth shielding unless

       you're building a day vfr machine with no radios.



   (2) wires that carry small, potentially victim signals

       (low voltages that carry intelligence in the form

       of voice, data or display signals). These will be

       circuits like microphones and small signal lines

       between various black boxes of a system.



       Wires that are used for grounding do no fall into

       either of these categories.



  Bob . . .

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