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Antenna cable?

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n233ee(at)gmail.com
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Posted: Fri Feb 02, 2018 8:48 am Post subject: Antenna cable?

The recent discussions about shielded cable brought to mind a question.  



I am in the process of installing a Garmin GDL-82 in an experimental aircraft.  The GDL-82 was purchased from Pacific coast aviation and arrived without any antenna cable since the installed length was unknown.



The online instructions warned of a possible signal loss if ‘standard’ RG 58 coax was retained from the transponder output to the antenna suggesting changing to RG 400 or equivalent.  I am under the gun to get the installation completed so a trip to the local Hutch & Son was an attempt to eliminate the shipping wait but they did not stock any 400 and did not have an equivalent.  They also thought the ‘400’ was an indication of the outside diameter as well as a lower signal loss.



I have found some RG-400 cable on both eBay and Amazon but their diameters are close to the RG 58.



Now the question is how do I determine the true RG 400 and what to use to limit the signal loss is a cable run of six feet from the transponder to the antenna.  The GDL-82 is four feet from the transponder and two feet from the antenna.  (The GDL-82 is spliced into the transponder output cable on the way to the antenna to pickup the code, standby, and altitude etc.)



I am inviting comments, suggestions and/or advice.  Thanks, Earl

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gilles.thesee(at)free.fr
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Posted: Fri Feb 02, 2018 9:07 am Post subject: Antenna cable?

Le 02/02/2018 à 17:42, Earl Schroeder a écrit :

 	  Quote: 	
		     a trip to the local Hutch & Son was an attempt to eliminate the shipping wait but they did not stock any 400 and did not have an equivalent.  They also thought the ‘400’ was an indication of the outside diameter as well as a lower signal loss.



 I have found some RG-400 cable on both eBay and Amazon but their diameters are close to the RG 58.



 Now the question is how do I determine the true RG 400


	


Hello Earl



Some info on the RG 400 coaxial

http://www.awcwire.com/productspec.aspx?id=rg400-coaxial-cable

Double braided shield, PTFE dielectric, etc.

And yes the diameter is close to that of the old RG 58.

B&C, Aircraft Spruce or any aviation supplier carry them.



FWIW,

-- 

Best regards,

Gilles

http://contrails.free.fr

http://lapierre.skunkworks.free.fr

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stein(at)steinair.com
Guest

Posted: Fri Feb 02, 2018 9:22 am Post subject: Antenna cable?

The 400 does not refer to the diameter (it's nearly identical to the 5...and beware of some of the Ebay stuff. There is much out there from recent hurricane sales that has been under water and can be corroded.  Not all of it of course, but SOME. Anyway, to be sure if it's correct, just buy it from an aviation/avionics shop and you'll be guaranteed it's good stuff that isn't old surplus or something.



Now, as an aside - depending on the transponder you have (and how it's performing before the upgrade/addition of the 82), the 58 you currently have might work just fine, at least temporarily.... 



Cheers,

Stein



--

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nuckolls.bob(at)aeroelect
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Posted: Fri Feb 02, 2018 10:44 am Post subject: Antenna cable?

 	  Quote: 	
		  

 I have found some RG-400 cable on both eBay and Amazon but their diameters are close to the RG 58.



 Now the question is how do I determine the true RG 400 and what to use to limit the signal loss is a cable run of six feet from the transponder to the antenna.  The GDL-82 is four feet from the transponder and two feet from the antenna.  (The GDL-82 is spliced into the transponder output cable on the way to the antenna to pickup the code, standby, and altitude etc.)



 I am inviting comments, suggestions and/or advice.  Thanks, Earl 	


   It's difficult to 'fake' RG-400 . . . any of

   these offerings of cable and connectors will

   be suited to your task.



 https://goo.gl/jg2ocw

 

 

 

   Bob . . .

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Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Fri Feb 02, 2018 12:18 pm Post subject: Antenna cable?

I agree with Stein....for your cable lengths, RG58 will do just fine for 

the short run. Yes, the RG400 is better, especially for the long term, 

but whether the difference can be detected by a ramp test set or not...I 

doubt it. The RG 400 has clear insulation over bronze/gold looking 

interior and generally costs $3 and up per foot.



On 2/2/2018 9:42 AM, Earl Schroeder wrote:

 	  Quote: 	
		   

 

 The recent discussions about shielded cable brought to mind a question.

 

 I am in the process of installing a Garmin GDL-82 in an experimental aircraft.  The GDL-82 was purchased from Pacific coast aviation and arrived without any antenna cable since the installed length was unknown.

 

 The online instructions warned of a possible signal loss if ‘standard’ RG 58 coax was retained from the transponder output to the antenna suggesting changing to RG 400 or equivalent.  I am under the gun to get the installation completed so a trip to the local Hutch & Son was an attempt to eliminate the shipping wait but they did not stock any 400 and did not have an equivalent.  They also thought the ‘400’ was an indication of the outside diameter as well as a lower signal loss.

 

 I have found some RG-400 cable on both eBay and Amazon but their diameters are close to the RG 58.

 

 Now the question is how do I determine the true RG 400 and what to use to limit the signal loss is a cable run of six feet from the transponder to the antenna.  The GDL-82 is four feet from the transponder and two feet from the antenna.  (The GDL-82 is spliced into the transponder output cable on the way to the antenna to pickup the code, standby, and altitude etc.)

 

 I am inviting comments, suggestions and/or advice.  Thanks, Earl

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_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

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