Best way to splice together two pieces of small coax?

[Dave]

Needed to splice together two pieces of small coax (like 174 or such) and
was not satisfied with my final result. It *works*, but really needs to be
done better. What is the best way to splice together two pieces of small
coax?

Thanks...

Dave

 

[Sjouke Burry]

"Dave" <db5151@hotmail.com> wrote in
news:X4CdnWm_qrl3XP3SnZ2dnUVZ_rudnZ2d@posted.internetamerica:

Needed to splice together two pieces of small coax (like 174 or such)
and was not satisfied with my final result. It *works*, but really
needs to be done better. What is the best way to splice together two
pieces of small coax?

Thanks...

Dave

Attach two connectors. Not cheap but looks nice.

 

[Fred Abse]

On Wed, 14 Mar 2012 11:05:56 -0500, Dave wrote:

Needed to splice together two pieces of small coax (like 174 or such) and
was not satisfied with my final result. It *works*, but really needs to
be done better. What is the best way to splice together two pieces of
small coax?

Two SMA connectors, one male, one female.

--
"For a successful technology, reality must take precedence
over public relations, for nature cannot be fooled."
(Richard Feynman)

 

[Michael Black]

On Wed, 14 Mar 2012, Dave wrote:

Needed to splice together two pieces of small coax (like 174 or such) and
was not satisfied with my final result. It *works*, but really needs to be
done better. What is the best way to splice together two pieces of small
coax?

You don't. The splice will leak, and break the impedance of the coax.

Either get a larger piece of coax, or as others point out, add connectors
(male and female, or the same gender with an adapter). The best choice,
and actually easiest solution, is the larger piece of coax, the connectors
are likely expensive.

Michael

 

[Dave]

"Michael Black" <et472@ncf.ca> wrote in message
newsine.LNX.4.64.1203161101000.21226@darkstar.example.net...

On Wed, 14 Mar 2012, Dave wrote:

Needed to splice together two pieces of small coax (like 174 or such) and
was not satisfied with my final result. It *works*, but really needs to
be
done better. What is the best way to splice together two pieces of small
coax?

You don't. The splice will leak, and break the impedance of the coax.

Either get a larger piece of coax, or as others point out, add connectors
(male and female, or the same gender with an adapter). The best choice,
and actually easiest solution, is the larger piece of coax, the connectors
are likely expensive.

Michael

Yes, thank you. I am looking into replacing the entire piece of coax, and
the alternative of using SMA crimp connectors (unlikely, but worthy of
consideration.) Thanks to all for the input, and for helping me understand
better what I am actually looking at.
Much appreciated...

Dave

 

[Bob Myers]

In a pinch, I have had some success with the following. Note, however, that there's still going to be an impedance discontinuity at the splice, and that any such splice should be avoided unless you have absolutely no other option and need to get the coax reconnected right now.

1. Cut the coax so that you have two clean ends. Remove the outer insulation about 1" back on each end, and peel back the shield so that it lies back out of the way against the outer insulation. This works much better, of course, if you're dealing solely with a braid shield; if there's foil underneath, try to pull it back as well without removing any. Slide some heat-shrink tubing, about 2" long (and if you have any of the right ID), over one of the two cable ends.

2. Remove the inner insulation to expose 1/2-3/4" of the inner conductors.

3. Slip a bit of thin heat-shrink tubing over the inner conductors; if it's possible to push it back under the shield/outer insulation, so much the better. If you can't get a piece of heat shrink in there, you'll have to insulate the inner conductor joint with a bit of electrical tape or some such.

4. Join the inner conductors using a classic "Western Union" splice and a bit of solder. Don't let the solder glob up on the splice - the idea is to get something not too much bigger than the original inner conductor.

5. Insulate the joint either with the bits of heat-shrink put on earlier, a little electrical tape, whatever; even with the heat-shrink, you may need to add a top layer of tape. The idea is to get a layer of insulation in here roughly the same OD as the original inner insulator.

6. Bring the shields back over the insulated splice from each side. You probably will not be able to get the two shields to touch very well or overlap sufficiently for a good joint. Use a bit of copper foil tape wrapped around the joint to give you some place to solder both shields to. Again, the idea is obviously to replicate as closely as possible a continuous shield in the final result. Tack solder the shields to the copper tape all around.

7. Cover the splice with the outer heat-shrink tubing added earlier, or using electrical tape.

Again, this is NOT going to perform anything like a continuous piece of cable, and I mention it here only because there are some time when you NEED to get a cable back together and have no other options. Don't put the splice anywhere that the cable is going to be bent much, and plan to replace it with a new continuous run as soon as you possibly can, or at the very least with a couple of new connectors as others have mentioned. This is most certainly a poor substitute for doing a proper splice with connectors, but it can often be better than nothing at all.

Bob M.