[TowerTalk] N connectors

[Steven J. Gehring]

Yep...center pin migration due to extreme temps happens with these
connectors.  But, the biggest issue I've seen with mil-spec type N's are
their incorrect installation (both in the government and civilian worlds).
If the center pin extends beyond (outside) the inner shield ring of the male
connector, you're asking for trouble.  The problem is that the inner lip of
the male pin butts up against the female tines prematurely, or before the
mating connectors are fully screwed together.  This has busted the female
tines in the female connector, or caused them to lose their spring tension,
through the actions of people who didn't know of this issue.  Obviously,
these people didn't inspect the connectors prior to mating them.  IMHO, the
tip of the male pin should reside flush to about 1 mm below the inner shield
ring.

The reverse is also true with these connectors. The male pin can be recessed
too far down inside the male plug.  If this happens, there won't be
sufficient mechanical and electrical contact, and this could lead to serious
problems (see the mail below for an example).  

I know there are newer and better designed N types out there, but I've
haven't used them yet.  I'm hoping they address pin migration to some
degree.  Can anyone recommend Manufacturers and p/n's of their decently
updated type N connectors?  Please pass along your detailed experiences and
successes with the newer varieties.  I know I'd really like to ditch having
to meticulously make the mil-spec variety.

73.

Steve Gehring, KZ9G
Bothell, WA  98012
E-mail: kz9g at arrl.net


-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Peter Sundberg
Sent: Friday, September 05, 2003 10:53 PM
To: TexasRF at aol.com
Cc: towertalk at contesting.com
Subject: Re: [TowerTalk] N connectors


I have done away with N-connectors in my VHF EME array as they are failing
during cold winter days. The problem is that at low temperatures (I live at
65.4N...) the center conductor of the coax gets shorter and the center pin
of the N-male is pulled out of the socket hence making poor contact. A split
second of 2kw RF vaporizes the center pin.. 
After having multiple failures during cold winters I now use PL259/SO239 of
good quality at the relay and as for the driven elements and powerdividers I
have soldered the coax direct and done away with connectors.

I dont think these problems will occur in places where the temperature swing
is somewhat less than -40C -> +35C....

73/Peter SM2CEW
www.qsl.net/sm2cew
	



At 15:04 2003-09-05 , you wrote:
>It is well known among vhf/uhf operators that N connectors will survive
twice 
>legal power through 432mhz with reasonable vswr. Even at 1296mhz they
survive 
>full legal power with low vswr.
>
>As others have mentioned, they will fail at any frequency under fault
>conditions. Heck, I even managed to smoke a 7-16 Din connector when the
shield let 
>loose on a 1296mhz PA output connection. The screen trip circuit would 
>have
>saved it if I had realized that the fault was external to the PA . You
live and 
>(hopefully) you learn!
>
>73/k5gw
>_______________________________________________
>
>See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
>_______________________________________________
>TowerTalk mailing list
>TowerTalk at contesting.com 
>http://lists.contesting.com/mailman/listinfo/towertalk
> 


_______________________________________________

See: http://www.mscomputer.com  for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more.  Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.

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