I've had the same differential expansion problem on a long run of bigger
coax with HN connectors. It would fail only at a certain time of day,
and I traced it with a TDR to a taped all-black junction that was in the
direct sun on the ground at that hour. I was able to prevent it in that
case by enclosing the cable joint in a short length of white PVC pipe.
Dave, W6NL/HC8L
On 8/24/25 12:17 PM, Richard (Rick) Karlquist wrote:
I have had this behavior on dozens of Type N's.
73
Rick N6RK
On 8/24/2025 11:41 AM, Michael Tope wrote:
I think the variety of type N connectors that don't capture the
center-pin in the body of the connector are the ones that are prone
to failure. On that variety of connector, the center pin is only
attached to the center-conductor of the coax. With wide swings in
temperature the differential CTE of the copper center-conductor
relative to the dielectric causes the center-pin to migrate in and
out. If there is enough differential contraction on the
center-conductor, the resulting tension can cause the unconstrained
center-pin to disconnect from the mating contact. I've seen this
happen on long cables terminated with this type of N-connector.
73, Mike W4EF............
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