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Re: [Amps] "N" Connector

Subject: Re: [Amps] "N" Connector
From: "Roger (K8RI)" <>
Date: Mon, 30 Dec 2013 01:49:21 -0500
List-post: <">>
On 12/29/2013 6:36 PM, wrote:
Couldn't you install a coax strain-relief to eliminate the problem?

Not sure where my answer went so I'll try again.

Depending on the coax type/size, put a one or two turn loop at each end.
Strain reliefs will not prevent the center conductor migration where a loop will. With 100' vertical runs of LMR-400 and 600 I prefer a "supported" 8" loop of 2 turns. A strain relief after the turns would help support the coax, but by themselves do not prevent the center conductor migration.

I've had bad experience with N connectors on long runs of coax in the
wintertime. My theory, unsupported either by other facts or long
deliberation is that the coax length shrinks slightly at low temperatures
and tends to pull the center pin out of its making connector. The early
symptom is always an intermittent loss of receive sensitivity, but in

I don't think there is that much difference between the inside and outside with typical temp changes here in MI. (+105 to -10 F). I hadn't thought about it before, but the only failure were feed lines to center fed, half wave dipoles. The coax also was quite active with lots of movement from the wind.


Roger (K8RI)

cold  nights I've lost transmit continuity as well. Personally, I
don't care
for N connectors (at least at HF frequencies) but in the olden days
when I
was using lot of military Transco coax relays and motorized coax switches
there wasn't much of an alternative.
Jim W8ZR

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