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Open in coax

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Subject: Open in coax
From: (Michael Valentine)
Date: Tue, 15 Oct 1996 08:18:11 -0400
Fred Hopengarten wrote:

> K1VR:  Curious.  I discovered the same problem last winter here.  When
> things got REALLY cold last February, my 40 meter beam stopped working.
> The problem turned out to be that an N connector splice in the K1XX
> asynchronous transformer (to feed a 50 ohm beam with 75 ohm hardline) had
> experienced this "n-connector pullback".  The inner body of the N
> connector, on the female side, had retracted and was no longer making
> contact.  Instead of attributing it to warm weather, as Glen K6NA does, I
> had attributed it to cold weather.  However, at that time, someone wrote
> me that he had discovered the same problem in several places with N
> connectors on RG-213 at KN8Z, where the N connectors were taped
> vertically to a tower leg (as was true in my case).  So it may be an N
> connector problem, not a weather problem.

Hi Fred!

N-connectors are famous for retracting the center pin from either
temperature extremes or mechanical stresses on the cable.

That is unless you use connectors with CAPTIVATED center pins!  The
garden variety "N"s that hams tend to use are intended for short run, 
inside the building, instrumentation or equipment jumper use.  Any 
n-connector used on a long run or outside in the weather needs to have 
the center pin held (captivated) in place so that it can't slide in or 

Mike - WA8MSF EM79sd

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