Post by Larry Fisherp.s. I'm waiting on a new set of precision strippers (two weeks and
$147) to restart the saga of wiring a COS11 to a TA5F. I think the
trick is to remove the insulation perfectly without distorting the
wire.
My precision strippers are a very small pair of $5 flat diagonal cutters
from Radio Shack.
Today I wired the COS-11 that I just received as a replacement. As I
promised, I paid attention to my methods in case there's something I do
that can benefit others here. I don't seem to find tiny wires and
connectors as much of an issue as some do.
Having the right tools helps. I find that the number one thing needed,
however, is patience. I make it a point not to do this type of fine
work if I'm in a hurry. That helps immensely.
The soldering iron I usually use for this is a small, rechargeable
battery powered unit with a needle tip. However, today the SRBPUWANT
didn't hold a sufficient charge and I used a standard Weller SP-23.
It's pretty hot for such tiny connectors but with a deft touch, it works
fine.
Actually, having an iron that is too small for a job can often damage
components more easily than one that is a bit too hot since it requires
that the connections are heated too long and the heat has too much time
to be transferred to other areas. A proper connection is made when you
have just enough time to "melt in" the solder. Then, you should keep
the joint stationary until it has cooled sufficiently. The iron should
be applied to the connection, a touch of solder applied between the iron
and the connection and then the connection, in turn should heat the
solder that you apply above the connection, melting it into the
connection. I hope I said that right. For such tiny connections as
these, however, it's hard to actually do it that way, so I just do the
best I can.
One of the most important solding tips I can offer is to properly tin
each part of a connection before soldering the connection. That makes a
big difference.
Okay, here are the steps I used today to put a TA5 connector onto a COS-11:
Step 01: I cut the COS-11 cable to the length I want it to be. I make
sure to leave three or four inches extra in case of a re-do.
Step 02: I circumcise the outer insulation (of the wire -- come on, pay
attention). I do this by nibbling carefully around the perimeter (with
the small diagonal cutters -- not my teeth). I then strip the outer
insulation off. The technique I use might have something to do with my
success with tiny wires in general. To strip the insulation off, I use
the small pair of $5 flat diagonal cutters but I don't squeeze the
cutters tight. I hold them in such a way that I am controlling the
"bite." Something akin to using the combination of my hand and the
cutters as an infinitely adjustable pair of wire strippers. Here, a lot
of stripping experience helps. It helps even more if the stripping was
done with wires as opposed to garments.
Step 03: I unbraid the shield and pull it out apart from the two
insulated leads. Since there is such a thick bundle of shield wires,
along with a drain, I split the bundle in about half and trim one of the
halves down to where I circumcised the cable initially, and then I twist
the other group of shield wires into a nice, neat single lead.
Step 04: Using the stripping method described above, I strip the
insulation off of the two leads. I don't circumcise these -- they're
too small -- I just use the method I described -- but sometimes it takes
a few careful passes to get the insulation free. The trick is to leave
the inside conductors as untouched as possible. A lot of experience
with a lot of different wire types helps here.
Step 05: I separate the three leads (Black, White, & Ground) from each
other so I can get at them easily.
Step 06: I light a match.
Step 07: I carefully burn off the nonconductive "strength threads" that
accompany the wires. I'm careful not to use too much flame or I'll
damage the insulation.
Step 08: I twist each of the three leads to compact and straighten it.
Step 09: I tin each of the three leads with solder and a soldering
iron. Just like with the match, too much heat will damage the insulation.
Step 10: I examine each of the three leads to make sure that they are
tinned.
Step 11: I trim the excess length from the tinned leads.
Step 12: I thread the necessary pieces of the TA5 onto the cable.
Step 13: I thread the two pieces of heat shrink tubing, that I'll use,
onto the cable.
Step 14: I make a loose knot around the pieces that are threaded onto
the cable to keep them from accidentally falling off as I'm
concentrating on other steps.
Step 15: I make a small vice out of a pair of pliers and a rubber band.
Step 16: I position the connector -- pin side up -- in the jaws of the
"vice."
Step 17: I tin each of the leads of the connector with solder. Careful
here, too much heat will damage the connector.
Step 18: I solder the jumper into place.
Step 19: Soldering the two capacitors into place is one of the
trickiest stages. I use the surface mount type that are available from
Lectrosonics. First, holding it with tiny needle-nose pliers, tin the
edges of the capacitor and then carefully tack one side into place, then
the other, then resolder each, leaving time for it to cool in between.
Step 20: I solder the three leads into place.
Step 21: I check the wiring instructions to see that everything is
connected properly.
Step 22: I inspect each connection with an 8x loupe.
Step 23: I carefully plug the receptacle portion of the connector into
a transmitter and test it out. Special care is required when removing
the receptacle (I use needle-nose pliers) since the connector isn't
assembled at this point.
Step 24: I either (a) rejoice or (b) back up a few steps and redo parts
of the job.
Step 25: I slide the smaller heat shrink tubing into place and
carefully shrink it using a candle or small alcohol lamp.
Step 26: I assemble the connector and crimp the strain reliefs.
Step 27: I finish assembling the connector and slide the outer piece of
heat shrink tubing into place and shrink it down.
Step 28: I clean the heat shrink tubing with alcohol to remove any
carbon residue.
Step 29: I do a final test.
Step 30: I either (a) rejoice or (b) back up a few steps and redo parts
of the job.
The actual job takes about an hour. Finding where I left a tool I need
takes an indeterminate length of time.
This seems like a lot of work, and I guess it is, but if I'm patient --
and fantasize that I have a couple of scantily clad female assistants --
the time goes by quickly.
I may have left some steps out but this is the gist of how I wire up
COS-11 connectors. This is either the 8th or 9th one I've done. I've
also done B6s, and various others.
Stay tuned for some scenes from next week's episode...
John Blankenship, C.A.S.
Indianapolis
(email: my initials at mw daht net)