The company for which I previously worked designed and built recording
studio consoles. In order to eek out every bit of noise, that is
achieve the lowest noise floor, it was necessary to crimp and then
solder the lugs on the power supply cables on both ends. Crimping was
only OK and was done until it was discovered that also soldering the
lugs did lower noise floor a few dB. This leads me to conclude that
crimping AND soldering is preferred, leading to a lower resistance
connection.
For lightning grounding, joints and terminations, soldering alone is not
permitted. Crimping is required.
Yes, lugs can not be soldered alone. They must be crimped first and
THEN soldered. At the same time, some installations of aeronautical
equipment, along with NASA procedure, I do understand does indicate
sweating solder into the lug and it thereby wicking up into the stranded
wires makes for a "stiff" connection. This connection is reported to
break under vibration conditions. I've personally never experienced
such with ham equipment, although I've never carried any into space. I
suppose there is merit to this directive. Perhaps you FAA and NASA
types can expand this thought.
I am also aware with power distribution systems, a.k.a TVA, it is quite
common to use a crimp method to join wires. These conductors are
several thousand circular mills in size and are of many layers of
stranded conductors. When properly and completely crimped by a
hydraulic crimp machine, the joint is void of space. If fact, having cut
one of these in half just to see for myself, it appeared as a solid rod
with no voids observed. Thus the strands were compressed to that
degree. The center strand was steel as the messenger and the five
outer layers of aluminum were alternating in direction of rotation,
clockwise wound and counterclockwise wound.
In most cases, crimping connectors with a crimping tool which has the
correct die for the connector is noted to be satisfactory. On the other
hand, I've seen many cables in various ham applications which were
installed using what ever was handy to mash the sleeve. That is NOT
crimping. Crimping does not distort the tubular diameter nor round
shape of the sleeve as the correct size die prevents distortion of the
sleeve. A correct crimping tool puts a dimple in one side of the sleeve.
And now you know the rest of the story.
73
Bob, K4TAX
On 6/16/2019 7:27 PM, Nate Bargmann wrote:
* On 2019 16 Jun 18:50 -0500, Kidder, George wrote:
Interesting data, Don. I wonder if there is any information about
resistance variations between soldered and crimped terminals. One might
think that, with stranded wire, even a good crimp connection might not
solidly involve all of the strands, and might additionally deteriorate
with time since oxygen could get between the strands. A good solder job
should wet the wire through and (additionally) exclude oxygen. This
wouldn't be easy to measure, for sure, but these engineers are cleaver
people!
For what it is worth, the company I worked for prohibited the use of
soldered connectors for terminating bonding or power wiring. Especially
with regard to bonding, dissipating any lightning strike energy through
a soldered connector could cause it to enough to melt the solder. In
doing some microwave site upgrades I did pull out a previous generation
of bonding wiring that was soldered and some connectors had signs of
being heated since installation.
In my shack I use crimp connectors and a quality crimping tool with no
problems.
73, Nate, N0NB
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