Author Topic: Splicing Different Coax Cables  (Read 1377 times)

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GreekMan

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Splicing Different Coax Cables
« on: October 28, 2016, 03:49:14 AM »
well my mobile coax broke right in the junction of the thick and the thin wires.
(It is a Diamond factory one, solid core coax that is a bit thicker than RG-58 and a Rg174 like pigtail to pass under the trunk hood).

What is the suggested athod of splicing two coax cables of different thickness?

my plan is to.
Strip a long inner core section of the thin one and a short section of the thicker one.
Then ind the thin inner core around the thick one and solder.
insulate
Strip a short sheild section of the thin wire and reinforce with solder.
Strip a long shield section of the thick wire, bring back over the core, and solder on the thin wire shield

Also,
The wire had a metal cover over the junction of the 2 different thicknesses. I have removed that. cleaned it nad ncreased inner diameter to slip easily.
I plan to pour epoxy in it and slip over the spliced wire

What do you think?


Tevin

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Re: Splicing Different Coax Cables
« Reply #1 on: October 28, 2016, 07:22:35 AM »
This is a little hard to follow without photos.

Are you saying you have different size coax on a feed to a single antenna and radio?

There is no way to "splice" coax without screwing up the impedance and introducing a lot of other troubles.

I suggest you replace the entire run with one continuous piece of coax. If you must repair the break, use the correct PL connectors to rejoin the broken ends.


AD

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Re: Splicing Different Coax Cables
« Reply #2 on: October 28, 2016, 08:29:06 AM »
Yes photos please....
The only dumb question is the one that did not get asked!!

spacecase0

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Re: Splicing Different Coax Cables
« Reply #3 on: October 28, 2016, 08:33:12 PM »
a picture or diagram would be helpful,
but if you keep your junction way less than 1/4 wavelength (1/20 the 1/4 wave distance at most) you are likely going to be just fine
many low quality RF connectors (more popular than you might think) also mess up things, but hardly anyone notices

Flight-ER-Doc

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Re: Splicing Different Coax Cables
« Reply #4 on: October 29, 2016, 09:19:37 PM »
a picture or diagram would be helpful,
but if you keep your junction way less than 1/4 wavelength (1/20 the 1/4 wave distance at most) you are likely going to be just fine
many low quality RF connectors (more popular than you might think) also mess up things, but hardly anyone notices

A properly installed, quality connector (like a silver and teflon Amphenol) will insert a 0.1db loss into the system.  A splice will insert a 15 or 20db loss.

Just get a new NMO mount and replace the cable.

spacecase0

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Re: Splicing Different Coax Cables
« Reply #5 on: October 30, 2016, 12:08:27 AM »
I have not seen an Amphenol connector for sale at a local store in the last 20 years,
I know I can web order the good ones, but I have piles of the crummy ones I got locally

GreekMan

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Re: Splicing Different Coax Cables
« Reply #6 on: October 30, 2016, 03:44:01 AM »
here is the photo



I cannot knwo the way the cable was originaly spliced.

Flight-ER-Doc
Quote
A splice will insert a 15 or 20db loss.
that much?

anyway it costs me nothing to try it.  I guess I can check for losses with my SWR meter.

Tempstar

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Re: Splicing Different Coax Cables
« Reply #7 on: October 30, 2016, 08:06:26 AM »
Splices are never good, and are suicide in a mobile environment. I'd put an SMA on the small one and an N on the large one, with an adapter in the middle. SWR may be good, but losses won't necessarily show on an SWR meter. And if it goes high while mobile, is it worth a radio?
"Preparedness is a lot more than just buying stuff"

jdh

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Re: Splicing Different Coax Cables
« Reply #8 on: October 30, 2016, 12:24:59 PM »
If it was mine, I would put a female BNC connector on the RG-58 and a male BNC on the RG-174, negating the need for an adapter or splice connector, connect them together, wrap well with quality electrical tape to reinforce it and weather proof the connection, and call it good.

GreekMan

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Re: Splicing Different Coax Cables
« Reply #9 on: October 30, 2016, 12:39:45 PM »
hmmm I kinda like the idea....
cos BNC connectors can be assembled without crimping an outer shell

GreekMan

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Re: Splicing Different Coax Cables
« Reply #10 on: November 01, 2016, 01:44:40 PM »
while on the subject.....

how good is this type of splice connector?

Tevin

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Re: Splicing Different Coax Cables
« Reply #11 on: November 01, 2016, 05:38:06 PM »
If it was mine, I would put a female BNC connector on the RG-58 and a male BNC on the RG-174, negating the need for an adapter or splice connector, connect them together, wrap well with quality electrical tape to reinforce it and weather proof the connection, and call it good.

Short of replacing the entire assembly (which is what you should be doing), this ^^ is your best and probably only option. All I can add is that the connectors should be wrapped in coax-seal. Even then, it won't be the same.

I still don't understand why you're trying to fix this. You can buy a brand new prewired mounting with a length of coax for about $15 USD. There's not a lot of money involved here, so why screw around patching together old junk? Some things are not worth fixing.

GreekMan

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Re: Splicing Different Coax Cables
« Reply #12 on: November 02, 2016, 08:56:49 AM »
Cos I cannot find a cable like this again. All newer styles are just Rg-58 with no pigtail.
And the current wire is way better than RG-58. (1+mm solid core)
Cost wise, over here it is more than a day's pay
And just for the fun of it.

we are in a prepper comms forum, and i think we should train with making do with meager resources

AD

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Re: Splicing Different Coax Cables
« Reply #13 on: November 02, 2016, 06:31:00 PM »
Got a point there GM.  8)
The only dumb question is the one that did not get asked!!