15 Sep
2014
15 Sep
'14
4:43 a.m.
On Sun, 14 Sep 2014, Chuck Guzis wrote:
On 09/14/2014 03:58 PM, Dave G4UGM wrote:
You want the terminal less malleable. Friction fit terminals and contacts
have a certain "springiness" to them and that is how they achieve a low
resistance connection. Most terminals are made of plated brass or copper
alloy.
Whilst I prefer solder, many folks say crimp is
best. The problem with
solder is that it creates a stress point where the solder "ends" so if
the cable moves the cable can fracture. The heat can also alter the
temper of the cable and make it brittle. (Unlike steel some copper
alloys harden with slow cooling). This probably isn't an issue with
most classic computer projects....
I don't know, Dave. I work with brass a copper a lot, but not the
electrical kind, but the sheet metal sort. Generally speaking, heating
*anneals* nonferrous metals; cold-working hardens and eventually makes
them brittle.
For example, if I'm forming a piece of sheet copper using hammers and
rollers, I need to heat the copper to redness periodically, or it will
crack during working--at which point it's scrap. Copper is less
forgiving in this respect than brass.
So it seems to me that heating makes copper more malleable, rather than
brittle. To solder or not is probably a debate that will go on
for a long time.
But you do what you have to...
Back when I was running a lot of RG-58 thinnet, I picked up large lot of
surplus "no solder" BNC connectors, then noticed that they were made for
RG-59 (75 ohm, not 50). Rather than throw the lot out, I picked up a
few feet of thinwall copper tubing, threaded it to match the thread in
the connector and then soldered the RG-58 sheild into small lengths of
tubing, then screwed the tube and coax into the connector. It worked
for at least a decade on several 50 ft. runs until I finally pulled the
stuff out and replaced it with Cat 5 UTP.
That reminds me of the time I made a bunch of 50 ohm terminators. I didn't
have any terminators on hand at the time, but I did have a bunch of
screw-on BNC connectors, fillister head screws with the same thread as the
BNC connectors, and a package of 51 ohm 1% resistors. I cut the screws to
length, drilled a hole, and soldered one end of the resistor into the
screw. Then I simply screwed the screw+resistor into the BNC connector.
They were still working fine when I also replaced the last of my thinnet
runs with UTP. They'd probably still work fine today ;)