Re: Low cost coax connectors

On Sat, 27 Oct 2007 15:03:34 -0700, Jeff Liebermann wrote:
Rich Grise <rich@xxxxxxxxxxx> hath wroth:
On Sat, 27 Oct 2007 11:41:19 -0700, Joerg wrote:
Jeff Liebermann wrote:

About 25 years ago, my employer embarked on yet another bean counting
cost reduction adventure. Someone decided that all the coax cables
connectors going between boards was too expensive. So, I contrived a
stamped, board mounted, receptacle. That by itself wasn't very
interesting as those were already being sold by AMP. I eliminated the
coax plug by simply tinning the coax cable braid and the center wire.
We were using RG188a/u, which is the PTFE dielectric version of
RG174a/u. Cut the end off squarely and remove the outer jacket. Tin
the outer braid being carful not to let the braid bluge. Then run it
through a rotary blade stripper to trim the tinned braid to length,
expose some dielectric, and strip the center conductor. Tin the
center conductor, trim, and you have the world's cheapest coax plug.

And, if you have a production run of say, more than 100 or so, you could
make a little cutter to strip the jacket, cut the braid, and strip the
center conductor in one swipe. ;-)

That doesn't work. A bit more detail on the procedure:
1. Flush cut the coax cable.
2. Strip back only the outer jacket to expose the braided shield.
3. Tin the shield by either dipping in a solder pot, or using a metal
solder brush. You gotta be really good and fast with the pot, but it
produces the best looking soldering. Dipping only works well with
PTFE dielectric.
4. Use a rotary blade stripper to trim back the tinned braid. Do not
strip the center wire. The rotary stripping is fairly tricky as
variations in solder buildup will cause corresponding variations cut
depth. The trick is to tweak the die so that the guides do not rest
on the blobs of solder that always accumulate at the end of the wire.
5. Strip the center wire with a thermal stripper.
6. Tin the center wire.
There are some other tricks to this that I don't wanna get into.

If you try to strip back both the outer jacket, and the center
conductor to the final lengths, the solder pot will make a huge mess
of the exposed insulation and center wire. You could do it with the
solder brush, but there's always a blob of solder that forms at the
end of the shield, which has to be trimmed. That's difficult to do
with the rotary trimmer after the insulation has been removed.

I notice the first thing you say is "that doesn't work". Have you tried
it? The tool I've envisioned has three X-acto blades, arrayed radially
around a little jaw-thing, such that you push the jaw-thing up to the
cable to be prepped, and twirl it around the cable end while the X-acto
blades do their stuff.

This invention is NOT public domain, it is copyright© 2007, Richard M.
Grise, and this is First Disclosure for patent purposes.

Cheers!
Rich


.

Relevant Pages

  • Re: Low cost coax connectors
    ... Someone decided that all the coax cables ... coax plug by simply tinning the coax cable braid and the center wire. ... and strip the center conductor. ... Tin the shield by either dipping in a solder pot, ...
    (sci.electronics.design)
  • Re: Low cost coax connectors
    ... Someone decided that all the coax cables ... coax plug by simply tinning the coax cable braid and the center wire. ... and strip the center conductor. ... Tin the shield by either dipping in a solder pot, ...
    (sci.electronics.design)
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