Topband: Verifying integrity of 75 ohm coax.

[Jim Garland]

Helpful advice, Tom. Thanks. I've always worried about using silcone grease
on connectors. I understand it helps seal the connector, but my fear is that
it could interfere with the electrical bond.  On the face of it, getting
non-conducting grease on, e.g., the center terminal of an N-connector or
PL259 seems like asking for trouble.
73,
Jim W8ZR

> -----Original Message-----
> From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Tom
W8JI
> Sent: Tuesday, November 19, 2013 5:26 PM
> To: Bill Wichers; Gary at ka1j.com; Topband at contesting.com
> Subject: Re: Topband: Verifying integrity of 75 ohm coax.
> 
> > Just a suggestion: the T&B Snap'n'seal connectors also have "Seal nuts"
> > which can be bought separately. They're intended to seal out water from
> > the thread area on the F connector. They are basically a metal shell
with
> > some threads that captivates an O-ring such that tightening them against
> > the connector seals the o-ring between the threads and the F-connector
> > itself. They're intended to be a water seal, but they also make a pretty
> > decent locknut for an F connector even if you don't care about the
weather
> > proofing function.
> >
> > The newer CATV splitters, etc, have rubber boots that the male end seats
> > into. Those also reduce the possibility of loosening but probably not as
> > much as the seal nuts. If you have a problem with F connectors loosening
> > over time the seal nuts used as lock nuts might be worth a try. Note
that
> > the seal nuts will require about 1/8" or so of extra threaded area on
the
> > female connector compared to using the F connector alone so they don't
> > work with all female connectors. You need to make sure when using them
> > that the mail connector still seats properly (i.e. the coax shouldn't
> > rotate within the threaded ferrule of the male connector after it's been
> > tightened).
> >
> 
> If the connectors are properly tightened, there is no reason at all to use
a
> lock nut or any locking aids. It is as unnecessary as a lock nut or lock
> washer on a car lug nut.
> 
> I dealt extensively with F connectors in the 1980's for a company that had
> dozens of small CATV and MATV systems. They never had problems with
fitting
> getting loose. They had ten's of thousands of F connectors.
> 
> You have to **snug** the connector with a wrench or tool of some type. Be
> sure the threads are clean and use some light pure silicon or Teflon
> electrical rated grease. It does not take much pressure, around 10
> inch-pounds of torque is enough. With a four inch wrench, that's about 2
> pounds of push. DO NOT use the common 30 inch-lb wrenches. They will do as
> much harm as good. If you do not know what two pounds is to push a wrench,
> push on a bathroom scale with two fingers and get used to the feel. Then
> push the same way on a regular 4 or 5 inch wrench.
> 
> The worse tools of all to judge torque are pliers and connector drivers
that
> you spin with your wrist. End wrenches are the easiest to learn, because
you
> can snug with two fingers and really learn the pressure.
> 
> One way to avoid water problems on low frequencies is to flood the
connector
> with a pure silicon grease. Dielectric tune up grease for automobiles is a
> nearly perfect grease. There are some good Teflon based non-petroleum
> greases, also. DO NOT use Noalox or any other anti-seize. Noalox is
nothing
> but trouble.
> 
> On higher frequencies, like UHF or higher, you do not want to flood the
> connector. On lower frequencies, you can just flood it.
> 
> Connectors coming loose is like having connecting rod nuts falling off, or
> wheel lug nuts falling off. It has nothing at all to do with lock
hardware.
> They all stay on just as well when greased or oiled as they do dry or
> locked. They only loosen when not tightened properly or when the
mechanical
> connection is seriously abused.
> 
> 73 Tom
> 
> _________________
> Topband Reflector