I recall from my space hardware days that all the connector pins were
crimped. The crimp tools had to be regularly calibrated, and
periodically a pull test performed.
Crimped connections can be very reliable, but they have to be done right.
73,
Scott K9MA
On 2/16/2021 4:53 PM, Lux, Jim wrote:
On 2/16/21 2:05 PM, Rob Atkinson wrote:
I do not use solderless crimp on PL-259 connectors. PL-259
connectors were
designed to be soldered!
Starting a few years ago I experienced an intermittent and sudden loss
of signal into one or two of my receivers. Sometimes I'd be tuned to
a vacant frequency and have band noise and hiss in the background.
Then it would suddenly vanish. A few times I thought a strong
unmodulated carrier had come on frequency but it turned out to be a
sudden drop in RF level of 10 or 20 dB. I could pot up the RF gain
and get signal back and I began by suspecting some sort of bad relay
connection somewhere or a loose screw on a rear panel. Because it was
intermittent, it was tough to find and the problem plagued me off and
on. You all have been there before: One day I just happened to <fill
in the blank> and eureka -- in my case it was a jumper at a coax
switch I happened to nudge and strong band noise returned. Well
hello, what's this?
It turned out to be a jumper made with crimp connectors. You can love
them all you want but here's what happens--after a few years the crimp
- braid contact wears out. It ceases to make good low resistance
continuity for the extremely weak RF currents flowing. Maybe it's
mechanical failure; maybe it's chemical -- whatever it is, _braid_
does not hold up in a crimp long term. Compression connectors with
Heliax or other hard line with a solid compressible copper shield are
a different story. But in my opinion, any coaxial line using braid
for the outer conductor must be soldered to its connector.
On the other hand, there *are* crimp connections on stranded that are
more rugged than solder. I suspect it's a matter of connector design
and proper tooling. Cable TV uses almost exclusively crimp connectors
on a foil/braid and they have decent performance over the years.
I'd have to go look what we do for spacecraft, but in general, we
prefer crimped over soldered.
it's NASA STD 8739.4 - and Appendix B is about coaxial cable
problems. The concern seems to be if the clamping system clamps the
jacket, then the jacket will cold flow.
I don't know that there's a lot of practical difference between a
"wrench tightened" N connector that clamps the braid and a crimp
(assuming the crimp is properly done) - Amphenol 172102-2 is a crimp N
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Scott K9MA
k9ma@sdellington.us
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