[TowerTalk] Connectors

[Maurizio Panicara]

Hi Brian,

I try to reply, doing it between lines. It's not in my style, but tomorrow
I've a busy day with "only" four flights (as a passenger) with important
business meetings.
I need sleep.


----- Original Message -----
From: "alsopb" <alsopb@gloryroad.net>
To: <i4jmy@iol.it>
Cc: <towertalk@contesting.com>
Sent: Monday, April 02, 2001 8:43 PM
Subject: Re: [TowerTalk] Connectors


> Hi Mario,
>
> Most of these reasons for N connectors not being on ham gear don't
> seem relevant anymore.  Unfortunately, it appears that most hams(?)
> buy premade cables with connectors on them....

Premade cables stuff splits into three categories:
1) State of the art cables and connectors (i.e Shuner).
2) Cheap stuff.
3) Ugly

> However, I wonder which is worse a poorly made N connector or a poorly
> made UHF connector?  There are more ways to mess up making an N
> connector...

If one cares only a bit and takes the time, there are precise instructions
and lenghts to cut cables and fix "N" connector. The only "hidden" secret
with N is how to comb the shield.
In 29 years experience I've seen that UHF connector mounting is a very
personal art that vary depending by the author.
A poor mount is not desiderable in any case.

> You haven't acknowledged the problems of the center pin of the N
> connector migrating back into the connector via hot/cold and
> mechanical cycling of the center dielectric.  Lots of reports of N
> connectors failing this way.  I would guess fractionally as many N
> connectors fail this way as UHF connector failing via the center pin
> problems you describe.

Disagree.
It happens when a standard N connector is used with wrong cables (air
dielectric or foam) where the rubber ring can't keep (press all around) the
coax as it should, or when the mounting is not performed correctly.
There are anyway special N connectors to use with such special coax cables.


> I guess I am still not sold on the size of the type N connector center
> pin being large enough.  I guess I still believe in large surface area
> being important because of the skin effect.  There simply isn't much
> contact area. Just because you can run 6KW for 20 minutes in a lab
> condition with a freshly made connector does not imply that one wants
> to do so in adverse field conditions.

Not really.
Surface, size and skin effect have a minor impact than mechanical precision
and simpedance.
Take as a reference the data sheets of vacuum relays (i.e. some Jennings)
and note as the curent rating decreases from 2 MHz to 30 Mhz for the same
device.

> You also haven't discussed cost.  I figured out that in the past 40
> years I have made up over 1000 UHF connectors.  My guess is that the
> same thing with N connectors would have cost me another $2K or more.
> I'd rather spend my money elsewhere.  I really don't think the extra
> money would have bought me anything in performance, reliablity or
> anything measurable. (HF only here)

Why did you make so many connectors ? (Hi)
I guess you did help a lot of friends, I can't believe you have 500 cables
in your station.
Jokes apart, money spent with good cables and good connectors (UHF type
included) is an investment in performances and reliability !

> By the way the total number of connector failures I've experienced is
> probably under 10.  I consider this to be quite acceptable.  Half were
> due to UHF connectors manufactured with out of spec center pin sizes.

As I told you UHF mounting is quite an individual art.
I've no problem to believe that You, me and many others have developed a
failure saving mounting technique with UHF connectors, but this is not a
standard one and doesn't modify the inherent weaker points of UHF type vs N
type.

73,
Mauri I4JMY


> 73 de Brian/K3KO