[Elecraft] Terminal resistance

Mon Jun 17 04:32:30 EDT 2019

Interesting about the additional soldering and resultant noise reduction. A chart from the Indium Corp shows 63/37 solder to be about 11% of the conductivity of copper. I guess that's better than air though.

https://www.microwaves101.com/encyclopedias/soldering-basics#chart
Microwaves101 | Soldering Basics<https://www.microwaves101.com/encyclopedias/soldering-basics#chart>
Click here to go to our main page on packaging. New for February 2019: here's a link to an update on lead-free solders, from Aerospace Corporation, from 2011.In case you were wondering, the issues with lead-free solders have never really gone away. To put it in perspective, 88% of lead consumed in the United States is used in storage batteries, which are not subject to RoHS.
www.microwaves101.com

Chuck Hawley
 c-hawley at illinois.edu

 Amateur Radio, KE9UW
 aka Jack, BMW Motorcycles

________________________________
From: elecraft-bounces at mailman.qth.net <elecraft-bounces at mailman.qth.net> on behalf of Bob McGraw K4TAX <rmcgraw at blomand.net>
Sent: Sunday, June 16, 2019 10:03 PM
To: elecraft at mailman.qth.net
Subject: Re: [Elecraft] Terminal resistance

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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