[BULK] - RE: [TowerTalk] Re: Cutting braid - Installing PL259

[Steve Katz]

Well that's interesting. You referenced several times in
your posts "...what Amphenol recommends..." etc. - for
example not pre-tinning the braid and now the 0.00" braid
edge dimension. I was surprised because the old assembly
instruction sheet from Amphenol that I've always used
indicates that 1) there should be a "set back" between the
face of the dielectric and the edge of the braid (not flush
cut) and 2) the braid and center conductor should be
pre-tinned. 

::The pre-tinning is a really bad idea in most cases.  For one, it's just
not required, in order to wet solder to copper.  For another, about half the
cables "we" (amateurs) use already has tinned braid, so tinning again helps
nothing except to possibly deform the dielectric from heat, which is not
desirable.  The "setback" dimension you describe is normally 1/16" or 3/32",
a very small space, there entirely to help prevent possible short-circuits
from braid to center conductor.  But it doesn't do that job, since a
renegade strand of braid ("whisker") can occur whether you use any setback
or not.  If you cut the braid very sharply and cleanly, as can be done by a
sharp (new) razor blade, there is zero advantage to any "setback" dimension,
and in fact using one makes the connectors perform a little worse at higher
frequencies.  Using braid to cover all the dielectric helps maintain
constant impedance, better than not doing so.


Based on your comments I thought maybe they had re-written
the assembly instructions since the assembly sheet I have is
from a thirty year old Amphenol publication. I just checked
the Amphenol site
(http://www.amphenolrf.com/products/assemblyInstructions/274
.pdf) for the current assembly instructions for the 83-1SP
series and today's version is nearly identical to the one I
have. I don't know about the "military specifications" you
referenced but on the assembly page above they do define a
small set back of the braid from the end of the dielectric
and they do specify pre-tinning both braid and center
conductor. The note on preparation certainly supports your
razor blade approach since they do specify "All cuts are to
be sharp and square".

::The published assembly data is for non-commercial use.   The military
specification is actually specification #PL-259.  I haven't looked to see if
this is public domain or not, but most military specifications are *not* on
line, and are available from the Government Printing Office (mail order) or
purchased from third parties specilizing in military/government standard
document reproduction, such as Document Engineering (http://www.doceng.com).
Although this is an old military specification, it was drafted by Amphenol,
as the inventor company.



You obviously found a solution for your production line and
I'll try your razor blade approach for cutting but think
I'll stick with the vendor on the other steps.

::Do what works best for you!  But my attitude is, "If it takes you longer
than one minute to strip the cable and install a PL-259, you're obviously
doing something wrong."  I give live demos of this process at the TRW Swap
Meet and other large ham gatherings, and people are astonished that it
really only does take 60 seconds, start to finish, and results in a perfect
installation every time.  73 de WB2WIK/6


Thanks for your description and suggestions. It's amazing
how many different approaches are used considering how
common these connectors are.