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Permanet Splicing RG400

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jc-matronics_aeroelectric
Guest

Posted: Sun Jul 31, 2011 6:57 am Post subject: Permanet Splicing RG400

I am wondering if there is a way of permanently splicing together 2 

sections of coax wire together. I realize I could use a male/female 

connector. However, i would like to route this cable thru a wing 

conduit, and the bulky connectors would just get in the way.



Thanks for any insights!

Jae

RV-10

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jul 31, 2011 8:02 am Post subject: Permanet Splicing RG400

At 09:51 AM 7/31/2011, you wrote:

 	  Quote: 	
		  

<jc-matronics_aeroelectric(at)jline.com>



  I am wondering if there is a way of permanently splicing together 

 2 sections of coax wire together. I realize I could use a 

 male/female connector. However, i would like to route this cable 

 thru a wing conduit, and the bulky connectors would just get in the way.


	


    This only works well with heat-resistant,

    modern coax like RG400 or RG142.



    Slip 2 pieces of 1/2" heat shrink, 4 inches

    long over ends to be spliced.



    Strip back 1-1/2" of outer jacket and

    push braids back to the end of the jackets.

    Cut center conductors to 1" per side, then

    strip 1/4" per side. Lap solder center

    conductors. Wrap exposed joint with Teflon

    pipe thread tape. It's okay if the tape

    overlaps the ends of the center conductor

    insulation and leaves a bit of a 'lump'.



    Then take braid from one side and pull it

    over the center conductor splice. Wrap

    the last 1/2" with a few turns of fine strand

    wire taken from some airframe wire. Solder

    wire wrap very thinly to the braid. You're

    wanting this to get 'fixtured' and 'smooth'

    without getting 'thick'.



    Pull the other braid over the fixtured

    braid and repeat the fine-strand-wire wrap.

    Then solder the braids to each other. Use

    63/37 tin-lead solder.



    Cover joint with one piece of shrink and heat

    it. Cover with second piece of shrink and

    heat that.



    Yeah, this puts an 'impedance bump' in your feedline

    that can be observed with the proper test equipment.

    But if you had identical installations on the

    airplane except for one pristine feedline and

    one spliced feedline, you could switch back and

    forth between them and observe no difference

    in performance.



    I used to do this with RG-58 . . . it's pretty

    tricky due to low melting temperatures of the

    PVC and PolyE insulations but it CAN be done

    with practical success.

   Bob . . .

rparigoris

Joined: 24 Nov 2009
Posts: 805

Posted: Sun Jul 31, 2011 8:16 am Post subject: Re: Permanet Splicing RG400

Hi Bob



Thx. for your explanation on how to splice coax cable.



Question:

What is airframe wire? Strands of stainless or plain steel control wire rope (control cable)? Or perhaps you mean thin copper strands of Tefzel wire that is hanging around?



"a few turns of fine strand wire taken from some airframe wire"



Thx.

Ron Parigoris

nuckolls.bob(at)aeroelect
Guest

Posted: Sun Jul 31, 2011 9:18 am Post subject: Permanet Splicing RG400

At 11:16 AM 7/31/2011, you wrote:

  	  Quote: 	
		  --> AeroElectric-List message posted by: "rparigoris" <rparigor(at)suffolk.lib.ny.us>



 Hi Bob



 Thx. for your explanation on how to splice coax cable.



 Question:

 What is airframe wire? Strands of stainless or plain steel control wire rope (control cable)? Or perhaps you mean thin copper strands of Tefzel wire that is hanging around? 	


   Sorry, 'hookup wire' is perhaps a better term.

   A piece of 22AWG, M22759 will yield some nice

   strands of 34AWG wire nicely suited to this

   'fixturing' task. 



   When you're lap-splicing stranded wire, you

   can use a strand from the base conductor

   as shown . . .



  http://tinyurl.com/dgg2nb 



   But in the coax-splicing task, you need to

   acquire the fixture strands elsewhere.



 

   Bob . . .    [quote][b]

rparigoris

Joined: 24 Nov 2009
Posts: 805

Posted: Sun Jul 31, 2011 9:53 am Post subject: Re: Permanet Splicing RG400

Hi Bob



Thx. for the reply.



Ron Parigoris



Do not archive.

jc-matronics_aeroelectric
Guest

Posted: Mon Aug 01, 2011 3:49 pm Post subject: Permanet Splicing RG400

Wow, thank you Bob for that detailed explanation. Now that I have the 

"how" I have to decide if it's worth it.



Just checked on the price of RG400, and it seems to be around $2.50/ft. 

Egads! I swear that is 2x more than what i paid for my original order 

just a year ago!? That's $33 savings if i can splice the coax myself. 



Jae

RV-10

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Aug 02, 2011 6:58 am Post subject: Permanet Splicing RG400

At 06:45 PM 8/1/2011, you wrote:

 	  Quote: 	
		  

<jc-matronics_aeroelectric(at)jline.com>



  Wow, thank you Bob for that detailed explanation. Now that I have 

 the "how" I have to decide if it's worth it.



Just checked on the price of RG400, and it seems to be around 

$2.50/ft. Egads! I swear that is 2x more than what i paid for my 

original order just a year ago!? That's $33 savings if i can splice 

the coax myself. 


	


    Yeah, that stuff has gotten expensive . . . but

    anything with copper in it has been given an excuse

    to jump in price . . . even if copper is the least

    expensive commodity in the product.



    I'll poke around my surplus/used sources and see

    if I can dig up some 400 at more attractive prices.

    But for our purposes, the splice I described is

    pretty easy to do and has no observable impact

    on performance. For that matter, you could consider

    RG58 for anything except GPS and Transponders.

    That coax performed well for decades.

   Bob . . .

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Aug 02, 2011 7:21 am Post subject: Permanet Splicing RG400

 	  Quote: 	
		     I'll poke around my surplus/used sources and see

    if I can dig up some 400 at more attractive prices. 	


    Don't forget eBay. For example, if your run is 9' or

    less, you can buy something like this:



  http://tinyurl.com/4x3a3na 



    which is pre-assembled with connectors. But it's $10

    with free shipping. Cut the connectors off and install

    your own.



    Also, consider the modern Poly coax LMR400. It's larger

    in diameter but connectors for it are easy to get.

    It's losses at the high frequencies are on par with

    the fancier stuff and a whole lot cheaper. If the

    size is not a turn off for your particular application:



  http://tinyurl.com/3k86rvm 



 

 

   Bob . . .    [quote][b]

stuart(at)stuarthutchison
Guest

Posted: Wed Aug 03, 2011 3:39 am Post subject: Permanet Splicing RG400

G'day  Bob,

  

 I  assume RG58 TNC/BNC connectors are fine for RG142, +142 or 400 coax?   I don't understand why TNC connectors are listed at Aircraft Spruce for  between $35 and $62 each, yet even silver-plated types are avaliable here  in Australia (from RS) for around $10-15.  What am I missing  please?

  

 Cheers, Stu

   [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Wed Aug 03, 2011 7:09 pm Post subject: Permanet Splicing RG400

At 06:35 AM 8/3/2011, you wrote:

  	  Quote: 	
		   G'day Bob,

  

 I assume RG58 TNC/BNC connectors are fine for RG142, +142 or 400 coax? 	


   Yes.



  	  Quote: 	
		     I don't understand why TNC connectors are listed at Aircraft Spruce for between $35 and $62 each, yet even silver-plated types are avaliable here in Australia (from RS) for around $10-15.  What am I missing please? 	


   Not a thing. There are coax connectors that are

   essentially interchangeable but built and qualified

   to different specifications . . . which for our

   purposes doesn't matter. Prices on identical connectors

   can vary widely too depending on the supplier's

   volume, expertise and target customer base.



   When we added those connectors to our wesite catalog

   many moons back, I think I bought them in 100 lots

   for something on the order of 95 cents and sold them

   for $2. The exact came connector was commonly offered

   at $3.50 in single lots. But if you bought a mil-qualified

   connector in small quantities, it could be pretty

   breathtaking without being any 'better' for what you're

   needing to do.



  http://www.alliedelec.com/search/productdetail.aspx?SKU=7131150

 

  http://www.alliedelec.com/search/productdetail.aspx?SKU=7131003

 

 



 

   Bob . . .    [quote][b]

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