F-plug need to be fully tightened?

Hand tight is sufficient, yes. Its rare I would tighten them up any more than hand tight for most jobs,

Yep. a hand job is just the biz....... :)

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 floor".

-- Sue

Sorry, Sue, it won't be more reliable, just very convenient if you are continually removing/replacing F connectors into various pieces of equipment......... By your reasoning, then both will fall off :) The push on F connector adapter is very prone to falling out of the back of whatever it's connected to....... but boy, is it handy :)

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 intermittent.

Man of experience! :)

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 layer.

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 span.

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.

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.

On Tue 16 Sep08 01:08, GoldIntermetallicEmbrittlement wrote in :

Hi, I am the OP. I can see that the threads of the plug and socket would grip one another and probably make good electrical contact.

However, I can't see the wire centre connector necessarily making electrical contact through that grease.

Does the centre conductor actually have to make electrical contact or is 240 MHz RF able to propagate properly across the plug/socket join even if the centre conductor is not electricially continuous?

IYSWIM.

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 problem

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.

|>

|> -------- |>

|> 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?

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.

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 installations.

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.

In Peter Wright's book Spycatcher, he describes a technique for remotely bugging the phones of the day - 1950s - by using an RF carrier to bridge the hookswitch by means of its innate capacitance and therefore activate the microphone. A dim memory suggests it used a frequency somewhere around Medium Wave - about the same as ADSL.

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 warrant.

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.

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

I mentioned them earlier in the thread.

-- Sue

Another field you don't know anything about, Phil. I worked as the engineer for a major MSO years ago. I was responsible for all the electronics in CATV systems scattered all over the US. You are a ham radio operator, and should be familiar with CFR 47. There are a lot of regulations in there concerning CATV equipment & installations. CATV systems share some frequencies with airports and commercial airliners.

It is required by the FCC. The cable company is responsible for any RF radiation from their system, from their antennas, to every TV they provide their service to. Most commercial grade 'F' connectors had a specification of 1/8 to 1/6 turn after finger tight to meet the radiation & ingression specification. If they detect leakage they have to find the source. If it is from inside your house and you either aren't home or won't let them in, they are required to disconnect your service until all repairs are made.

There is no reason to keep disconnecting the cable modem.