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Antenna Connections

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DJones

Joined: 28 Jul 2006
Posts: 2
Location: New Mexico

Posted: Mon Jul 31, 2006 5:53 am Post subject: Antenna Connections

I would like to know what is the best way to connect the marker beacon antenna coax to the audio panel.  I also have an old Narco Nav 12 which uses some very small coax type cable, is this just shielded wire?

I remember seeing something about putting a BNC connector on small shielded cable on Bob's site, but I can't find it now.

Thanks

Don

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_________________
Don

FLYaDIVE(at)aol.com
Guest

Posted: Mon Jul 31, 2006 7:29 am Post subject: Antenna Connections

In a message dated 7/31/06 10:06:07 AM Eastern Daylight Time, 

pilotx2(at)zianet.com writes:



 	  Quote: 	
		   I would like to know what is the best way to connect the marker beacon 

 antenna coax to the audio panel.  I also have an old Narco Nav 12 which 

uses 
	


 	  Quote: 	
		   some very small coax type cable, is this just shielded wire?

  I remember seeing something about putting a BNC connector on small 

shielded 
	


 	  Quote: 	
		   cable on Bob's site, but I can't find it now.

  Thanks

  Don

===============================
	


Don:



What audio panel do you have?  Is the marker beacon receiver part of the 

audio panel or is there a separate box?  Since you have a NARCO NAV 12 I'm 

guessing that you have a NARCO Audio Panel.  Some of them did have separate marker 

beacon receiver boxes.



Now, as for connecting the NAV 12.  Some of them did have a separate BNC 

connector and even if it did not there is a location for the connector.  It can be 

paralleled up with the lousy coax connection on the edge card connector.  O!  

Nope ... it is NOT just a shield it is a small diameter 50 ohm coax. Probably 

RG-117.



I don't know if it was on Bob's site that you read about the BNC connector 

but I know I posted a few notes/articles on coax and the BNC connector.



Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada

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DJones

Joined: 28 Jul 2006
Posts: 2
Location: New Mexico

Posted: Mon Jul 31, 2006 8:03 am Post subject: Re: Antenna Connections

 	  FLYaDIVE(at)aol.com wrote: 	
		  In a message dated 7/31/06 10:06:07 AM Eastern Daylight Time, 

pilotx2(at)zianet.com writes:



 	  Quote: 	
		   I would like to know what is the best way to connect the marker beacon 

 antenna coax to the audio panel.  I also have an old Narco Nav 12 which 

uses 

	


 	  Quote: 	
		   some very small coax type cable, is this just shielded wire?

  I remember seeing something about putting a BNC connector on small 

shielded 

	


 	  Quote: 	
		   cable on Bob's site, but I can't find it now.

  Thanks

  Don



===============================

	


Don:



What audio panel do you have?  Is the marker beacon receiver part of the 

audio panel or is there a separate box?  Since you have a NARCO NAV 12 I'm 

guessing that you have a NARCO Audio Panel.  Some of them did have separate marker 

beacon receiver boxes.



Now, as for connecting the NAV 12.  Some of them did have a separate BNC 

connector and even if it did not there is a location for the connector.  It can be 

paralleled up with the lousy coax connection on the edge card connector.  O!  

Nope ... it is NOT just a shield it is a small diameter 50 ohm coax. Probably 

RG-117.



I don't know if it was on Bob's site that you read about the BNC connector 

but I know I posted a few notes/articles on coax and the BNC connector.



Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada 	




Sorry, all the info would help huh, It is a Garmin GMA340 audio panel.  I wasn't sure how to connect RG-58 directly to the panel since the pins are too small.  I thought about connecting a wire to the shield just like every other shielded wire, but wondered if there was a better way.

I saw the small antenna lead on the old Nav 12 and wondered  if that was coax or just shielded wire.  It sure would work nice if it is available.

Thanks

Don

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_________________
Don

brian

Joined: 02 Jan 2006
Posts: 643
Location: Sacramento, California, USA

Posted: Mon Jul 31, 2006 10:09 am Post subject: Antenna Connections

On Jul , 26, at 2: PM, DJones wrote:



 	  Quote: 	
		   Sorry, all the info would help huh, It is a Garmin GMA4 audio  

 panel.  I wasn't sure how to connect RG-58 directly to the panel  

 since the pins are too small.  I thought about connecting a wire to  

 the shield just like every other shielded wire, but wondered if  

 there was a better way.


	


If they did not provide an obvious antenna connector, such as a BNC,  

you will need to connect your coax to the edge connectors. What you  

suggest, connecting a smaller-gauge wire to the coax braid, is the  

correct way to do this. I usually strip back plenty of jacket and  

braid so I have a couple of inches of center conductor. I get some  

smaller-gauge tefzel wire, strip it, wrap it around the shortened  

braid, solder, and then apply heat shrink over it. Now you just have  

two leads to solder to the pins of your edge connector.



Now, some distance away where it is convenient to get to later you  

should terminate the coax in a crimp-on in-line female BNC connector.  

This will let you easily disconnect the antenna for testing or  

trouble shooting.



Given how little it matters, and at the risk of horrifying some of  

you, you might want to just twist some wire together and solder to a  

bulkhead BNC connector right at the audio panel. (Or just use a  

couple of inches of your shielded audio cable.) 75MHz is low enough  

in frequency and the signal is so strong, that the little impedance  

bump caused by a couple of inches of non-5-ohm coax is not going to  

cause any problem.



 	  Quote: 	
		   I saw the small antenna lead on the old Nav 2 and wondered  if  

 that was coax or just shielded wire.  It sure would work nice if it  

 is available.


	


Did the Nav 2 have a built-in MB receiver? It has been years and  

years since I have used the Nav-2 (like +). I like the old Nav-22  

as it was a complete ILS system in a box, receiver, indicators,  

everything. It even had the lights for the MB receiver there but I  

don't think the Nav-22 had the MB receiver built in. Hmm, it may  

have as I think there were some with three antenna connectors. Two  

would have been VOR/LOC and GS so the third could only have been MB.



As for smaller coax, there is RG-4 which is 5-ohm coax with an OD  

of a little more than /8". There is a version using a teflon  

insulator which is RG-87 if I recall properly. You can find 5 and  

75 ohm coax in all kinds of ODs. Smaller diameter coax will have  

greater loss but may be easier to handle in a wiring bundle. For the  

frequencies we use, up to GPS, a couple of feet of small-diameter  

coax is not going to have a discernible effect on the performance of  

your systems.



The only places you should not use really small diameter coax is for  

the transponder and DME antennas. These are both transmitters with  

high peak power levels and the smaller coax will not have as good a  

voltage handling rating as larger coax.



Brian Lloyd                         6 Catterline Way

brian-yak AT lloyd DOT com          Folsom, CA 956

+.96.67.2 (voice)             +.27.92.788 (fax)



I fly because it releases my mind from the tyranny of petty things . . .

— Antoine de Saint-Exupéry

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_________________
Brian Lloyd
brian-yak at lloyd dot com
+1.916.367.2131 (voice) +1.270.912.0788 (fax)

I fly because it releases my mind from the tyranny of petty things . . .
- Antoine de Saint-Exupery

FLYaDIVE(at)aol.com
Guest

Posted: Tue Aug 01, 2006 6:52 am Post subject: Antenna Connections

In a message dated 7/31/06 12:09:13 PM Eastern Daylight Time, 

pilotx2(at)zianet.com writes:



 	  Quote: 	
		   Sorry, all the info would help huh, It is a Garmin GMA340 audio panel.  I 

 wasn't sure how to connect RG-58 directly to the panel since the pins are 

too 
	


 	  Quote: 	
		   small.  I thought about connecting a wire to the shield just like every 

other 
	


 	  Quote: 	
		   shielded wire, but wondered if there was a better way.

  I saw the small antenna lead on the old Nav 12 and wondered  if that was 

 coax or just shielded wire.  It sure would work nice if it is available.

  Thanks

  Don

================================================
	


Don:



I could not find the pin out of the Garmin GMA 340.  If you have it you will 

find the edge connector pins that are used for the antenna input.  

Just parallel up a short piece of coax to those pins and you will in 

business.  

Yes, you could use braided wire for flexibility but coax would also work.  

Just after you solder onto the edge connector secure the coax (or any wire) to 

the bundle.  Don. I'm using the term edge connector but I'm not sure what type 

of connector is being used on the GMA 340.  

Oh, if you wish you can install an inline female BNC for easy removal and 

testing.



As for the NAV 12, that is coax.  



Barry

"Chop'd Liver"



"Show them the first time, correct them the second time, kick them the third 

time." 

Yamashiada

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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:

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