[TowerTalk] PL-259 RF Coaxical Connectors

[Lux, Jim]

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