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F-plug need to be fully tightened?

Discussion in 'Electrical Engineering' started by Peto, Sep 15, 2008.

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  1. Peto

    Peto Guest

    I'm in the UK. I have the usual F-series connector on the coax
    entering my cable modem.


    I need to remove the connector every now and then so I lubed the
    threads with a smear of vaseline.

    At these RF frequencies (about 340 MHz) do I need to have true
    electrical contact between the plug and socket or is close proximity

    Would loose "hand tight" be sufficent?
  2. Palindrome

    Palindrome Guest

    Yep, for what you have in mind.

    You can also, IIUC, get adapters to go on the end of the F plug and turn
    it into "push on". Which will probably give a more reliable result as
    "loose hand tight" could very easily turn into "fallen off -lying on the
  3. Tim Perry

    Tim Perry Guest

    Grease should only be used when making a weather tight seal. i.e. outdoors.
    Typically a silicon sealer on 'N' connectors.

    Grease is not commonly used on F connector threads. Some weather tight
    models exude a sealer when crimped... but not on the threads.

    Hand tight is insufficient in this case because one of tech support's first
    questions is invariably "is your cable firmly attached" (I think it's on the
    cue card).

    Likewise any modification or adaptor you add will bear the brunt of blame in
    any "discussion" with tech support or field service.

    Constant plugging and unplugging of a F connector is not recommended because
    the jack is likely to wear out making the center conductor connection
  4. Jamie

    Jamie Guest

  5. Roy

    Roy Guest

    A little lube on any connector will only be helpful, those threads come
    pretty brittle from the factory, finger tight is ok here too., just make
    sure the fit is flush & snug all the way through to the end of it's
    screwy reach.

    Extreme BBW's ? Now I've seen it all };-)

    Roy Q.T.
    [have tools, will travel]

  6. Not true. There are several cities where the cable contractors followed
    the CORRECT methodology of SEALING their fittings with an
    anti-oxidant/moisture barrier.

    This has NOTHING to do with U/G coax cabling, which has a liquid
    sealant layer between the sheath (jacket) and the first braid or foil

    That's the threads, AND the "stinger". From a man hour POV, it is
    easier to simply plop a wad of it in the fitting, then the center
    conductor as well as the threads get the application. The media does not
    damage the connector or ANY fitting it gets mated with.

    Cable companies are SUPPOSED to cut back their fittings every ten years
    and place a new, properly treated fitting.
    THAT is what the original plan called for, and is also what SHOULD BE
    practiced. A ten year old uncoated fitting will have far more losses (can
    have) than one which has had anti-oxidant treatment after a ten year

    So, in a PROPERLY implemented cable system, treatment IS the common
    practice and teaching.

    Where did I learn this? Cincinnati's Time Warner (formerly CUBE) cable
    system. Way back in the early 80's. That was a DUAL system, so every
    run was twice the number of fittings. Every hard line run was twice the
    number. Dual taps at every node. All sealed from moisture.
  7. Tim Perry

    Tim Perry Guest

    You have a choice between conductive gunk which will tend to short out the
    connection or non-conductive gunk which will tend to block the flow of
    electrons where you would like them to flow. Take your pick. I pick neither.

    Time Warner in new York picks neither also, as least as far as far as indoor
    instillations go.

    Given the OP's constant unplugging of the cable I doubt oxidization will
    ever be a problem for him.
  8. The "techs" that "assist" you online are typically VERY DUMB.

    Yes, cable terminations can be very damaging to the female connectors
    they mate with.

    Most cable companies use a cable with a copper clad center conductor
    which is steel. First off, it is very bad for your side cutters.

    The second effect is that the center conductor ends up with a squared
    off "nose" (end) that is of a very hard material. This means that
    insertion into a female "f" connection WILL badly abrade on the two
    spring loaded "wipers" that get pushed aside by the center conductor when
    inserted. At that point, the two wipers become the connection to the
    center conductor.

    Several things happen with this cable type. First, the copper cladding
    on it is barely thick enough to even call cladding. So it wears off, or
    can wear fairly quickly. But a good hundred in and outs are likely not a

    Secondly is the abrasion on those two wipers. They can also "catch" on
    the nose of the center conductor and get deformed as it tries to
    literally push them out of the way. If the wipers are SPC (silver plated
    copper) then the abrasion leading to poorer performance can be a mere few
    insertion cycles. If it is brass or such, it may survive all 100
    insertions, and still yield the same loss.

    I have actually tried to round off the nose of my center conductor
    before and found it inserted easier. If one has a pure copper center
    conductor type cable, wear will not be an issue on the cable end, but it
    could still abrade or deform the female fitting internal parts. I have
    rounded those ends as well, but we are talking about severe overkill,
    considering that one only desires to insert these things a couple of
    times in their life.
  9. Guest

    | |> I'm in the UK. I have the usual F-series connector on the coax
    |> entering my cable modem.
    |> --------
    |> I need to remove the connector every now and then so I lubed the
    |> threads with a smear of vaseline.
    |> At these RF frequencies (about 340 MHz) do I need to have true
    |> electrical contact between the plug and socket or is close proximity
    |> enough?
    |> Would loose "hand tight" be sufficent?
    | Hand tight is sufficient, yes. Its rare I would tighten them up any more
    | than hand tight for most jobs,

    Tell that to the cable guy. They always tighten those things to the extreme.
    Maybe that's a good thing outside. But I've had to use big wrenches to get
    them off after the cable guy leaves. Maybe they think its a means to keep
    me from using a pirate box?
  10. You obviously have very little grasp of RF terminations.

    First off, NOBODY EVER uses a conductive medium to dress a cable

    If they do, then they must be as dumb as any idiot that thinks they do.
    T/W in NY is what? Queens? No, I do not give the folks in NY ANY
    credence on their capacity to know what the industry does or recommends
    gets done (more like their capacity to FOLLOW the method).

    They are the epitome of slam it, cram it, ram it, and jam it mentality,
    and no, they would not ever do anything that takes up extra time,
    regardless of whether it is the way one is supposed to do it, NOR would
    they ever CONSIDER the customer when doing it.

    They epitomize the term CABLE TRASH inasmuch as they cut a fitting and
    move on. Since it works, they could give a shit that it starts dropping
    dBs within a few months of termination without preparation.

    The wiper does not scrape the stinger in the same spot each time, and
    relying on an insertion move to "clean" one's connection is just plain

    It is far easier to replace the female "barrel connector" that most
    cable runs end up termination into. That way, all the insertions in the
    world can be made "brand new" by putting a new barrel fitting in the
    line. Still, the cream/paste/gel whatever is still going to be the best
    defense against oxidation.

    ANY freshly scraped wipers or stingers, etc. are going to actually be
    vulnerable to oxidation even quicker due to the bare metals, and
    dissimilar metals in the connection. The anti-oxidant keeps said
    oxidation from happening, and NO, it does NOT EVER "inhibit electron
    flow" as you have declared.,

    Hearing that from you makes one wonder if you know ANY electronics at

    Seeing your posts here in the past, I know that is not true, therefore,
    you must have latched on to some lame urban myth. What you should have
    relied on is your common sense.
  11. The "grease" should NOT be your choice of simple petroleum jelly. It is
    a specific medium. It does not inhibit OR push back against anything, so
    it would not keep the wiper from gliding into the proper, connected
    position... ever.
    With the proper medium it will not ever be kept from making said
    contact. It does not have the same consistency or viscosity as PJ does.

  12. No. There is an actual torque range spec for the fitting class.

    Also, a connection IS required. There is no "jumping the gap" at any
    frequency. RF lines are not your car's spark plug wires.

    The torques:

    For an SMA connection, it is between 7 and 11 in//lbs. An F fitting is
    slightly more than that.

    Hand tightening can yield about 3 to 5 in/lbs on a good day.

    There is an actual tool they use. It can easily be fashioned with the
    right tools.

    It is a snap-on six point (important) 7/16", deep length impact socket
    that has had the neck turned down to a diameter just greater than the 6
    points by about a millimeter or less. This allows access inside the
    security "bells" that are so often used to keep us out. Then, the socket
    needs to have a coax (number 6) wide slot cut into the entire length of
    the socket with a dremel cut-off tool, since the socket is hardened
    steel, you will not be able to use a hack saw or other steel based
    cutting device without going through a few of them.

    The socket sits on the cable, and slides up onto the fitting, and
    VIOLA! One can properly torque the fitting on or off, and also can
    access the security prevention devices incorporated into some system

    Finger tight is NOT enough on a cable that gets hooked up long term as
    a simple flexure of the cable can result in a loose connection.

    For a hook-up that you are going to be using over and over again, finger
    tight is fine as long as you know it is tight, the connection it good.
    Just remember that even the slightest cable flexure can twist it loose.

    So, if you are always "eyes on" then you should be alright because you
    know it is still tight.
  13. From: (Peto)
    I'm in the UK. I have the usual F-series connector on the coax entering
    my cable modem.

    I need to remove the connector every now and then so I lubed the threads
    with a smear of vaseline.
    At these RF frequencies (about 340 MHz) do I need to have true
    electrical contact between the plug and socket or is close proximity
    Would loose "hand tight" be sufficent?
    Actually, there is a tool that the cable guy uses to tighten cables on
    to the box & television., it's like a screwdriver but with a cylindrical
    piece on the end that holds the connector in place and helps you hold &
    twist it on better - your newtech website doesn't seem to carry it ..

    You could use your fingers with the item in the jpeg, that knurled area
    on the part let's you get a good grip on it, but they do need to be
    screwed on tight, nothing "loose".


  14. It barely worked on SOME susceptible phones at the time, and for a time
    after that, but none of the modern ISDN switched phones do, and the
    construction is different now as well.

    Then, all hook switches were exposed, just like the old pinball
    machines. Most are sealed switches these days. Still, there are far
    more and better ways of surveilling someone's activities.

    But sure... that was one "genius'" "discovery". Again, it required a
    specific set of circumstances to work. The main one likely being a
  15. Blarp

    Blarp Guest

    In the lab I used to check various sat-tv receivers. On the end of the
    sat feed we had an F connector with a special connector screwed in -
    it was spring loaded with a solid smooth centerpin. It could be
    pushed on and off without actually using the threads.

    No idea what it was called, but it was a stock item at the time.
  16. Palindrome

    Palindrome Guest

    Erm, I think that you will find that they are called "push on F plug
    adaptors". :).

    I mentioned them earlier in the thread.
  17. Guest

    So what, this is a UK group! :)
  18. Tim Perry

    Tim Perry Guest

    It seem I have made an error. I failed to notice this crosposted.

  19. Yes, we always referred to them as "Push Ons" as well.

    "Quick release" is incorrect as there is no "release" mechanism.

    Slip-on just sounds too much like a weak connection.

  20. Mine is constantly being hacked at by the kook group retards. When I am
    not using it, I turn it off. Most have a switch... nearly all have a
    dongle connection which can easily be pulled. No power, no bits moving.

    The guy can't be that goddamned paranoid.
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