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:[email protected]] On Behalf Of Tom W8JI > Sent: Tuesday, November 19, 2013 5:26 PM > To: Bill Wichers; [email protected]; [email protected] > 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 _________________ Topband Reflector
