Best brand coax and F connector for HD cable?

Hmm. Does this engineer work for a company that sells connectors or "high end" cable? Tightening an F connector will only affect the ground (shield) connection. It has no affect on the center conductor on which the signal rides.

I usually use gold plated connectors for audio gear though in all honesty none of the cheaper ones I used to use many years ago ever gave me any trouble. In fact, for A/V I defy anyone to tell the fdifference between gold-plated and cheap, push-on connectors.

That's strange. It has never happened to me and I always use finger tight connections on A/V gear. Perhaps the gentleman is speaking of connections exposed to the elements. In part of the snipped passage he mentions the effect of wind on the connectors.

"Robert L Bass" a écrit dans le message de news: ZO-dndcWLfVJyDXYnZ2dnUVZ snipped-for-privacy@comcast.com...

No he speak about connection in your home,cause we all know that are prone to blow a lot of hot air....

"Petem" a écrit dans le message de news: sdZph.30531$ snipped-for-privacy@weber.videotron.net...

Oups!!

that should have been read like that..

No he speak about connection in your home,cause we all know that YOU are prone to blow a lot of hot air....

Ed Nielsen wrote: > From a leading engineer in the CATV industry: "We did a scientific > research for a year on CPD and contact interfaces, the report shows us > that it is very important to break through the oxide layer to prevent a > non-linear behavior in contact surfaces. The torque varies with the type > of plating used on the F-connectors. >

What you're saying here is what I tell everyone who runs ANY kind of signals. The ground is at least as important (I believe more important) as the actual signal feed.

Everything you say squares with what I have worked with in commercial TV. On my outdoors connectors I use clear silicone heatsink (NOT bathtub silicone !! ) grease on the connectors before snugging them up. The grease prevents oxygen and water from corroding both the center conductor and the ground connection. The current antenna is 15 months old and doing fine so far. My cable of choice is Belden 1694A though their 1505 RG-59 is nearly as good loss-wise as the lesser brands RG-6. Yes, we use both types at work from analog NTSC and PAL to digital SDI (serial digital) and uncompressed HD SDI.

GG

I use either DC-4 or 5. Having worked for the company that invented them and I use them in connectors running high power. However I've never seen a clear heat sink grease. Dielectric, yes, but not heat sink. The only silicones I have seen for heat sink coupling are rater thick and white (Mainly Silicon Dioxide in 200 fluid)

There is another family of Silastic RTVs that are non corrosive for electronics work, but they are water proof, not moisture proof. DC-4 and DC-5 compounds work better. Just don't get them on anything you want to stick something on. The grease prevents oxygen and water from corroding both the center

Our cable company (Charter) seems to be using a compression clamp now.

Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair)

end" cable? Tightening an F connector will only affect

which the signal rides.

fluctuating shield connection will cause fluctuating impedance in the cable, which will in turn cause anomalies in the signal transfer.

connections on A/V gear. Perhaps the gentleman is

passage he mentions the effect of wind on the connectors.

I think exposure's the main issue. I do see signal problems when I move my cables using "cheap push-on" connectors even when the connection feels solid. Every now and again I see it when I move a threaded connection, and I then find out that threaded connected is not even hand-tight. They do seem to loosen up over time, especially the ones too awkward to really tighten well.

sdb

No dispute. However, I've not seen any such problem using finger tightened A/V connectors. I have seen numerous components damaged and even threads stripped by over-zealous tightening with everything from box wrenches to vice grips.

If you mean that you see problems

*while* moving the cables, we agree. However, once adjusted the cables remain unmolested during normal use.

There is the possibility that we use differing degrees of pressure when hand tightening. I have very large hands (XXL glove). Coincidentally, yesterday I had occasion to rearrange my main A/V stack. We had about 60 friends over for a party and I had to put sound outside for dancing (Brasileiras *love* to dance). I have not yet installed my outdoor speakers.

At any rate, all of the F and RCA connections were just as secure as when I set the system up almost a year ago.

Hand tightening is marginal. Go with an awkward location or significant movement and hand tightening is likely not to be enough.

However, Robert is also right. Give most people a wrench and they will over tighten anything. There is a reason that good manufacturers use torque limited wrenches, even on large screws.

Got small screws or things mounted in fragile materials, and even a screw driver handle can over tighten things. The best way to handle it is as a "finger tight" multiplier.

I like the idea of the plastic device that someone pointed out. A clam shell that can reach over a bulkier body. Plastic so that people don't want to over tighten it. However, that cone shape is so bulky that I can't see it being all that useful. If it was narrower with a couple finger tabs so that it can be stronger than normal finger tight but still get into backs of equipment with the typical crowded, recessed, fittings.

Looks great. The tool I had was really just a cut-open socket welded to a screwdriver handle. The SNS connectors have a large body and the wrench couldn't fit over it. The ones you've shown have a larger area and should work nicely. They are also shorter and look much easier to manuever in small spaces. I have an old tendon injury that makes tightening those SNS connectors by hand really painful.

-- Bobby G.

Horribly bad practice! Running coaxial cable through metallic conduit will change the impedance. Also running transmitter coax alongside receive coax in the same cable bundle is a fool's bet and assumes zero VSWR on the transmitting antenna. You may be an old-timer, but I've been around the track a number of times myself and can tell you, unequovically, what you're doing is wrong.

The characteristic impedance of a cable is a function of the dimensions of the center conductor and the distance to the inside of the shield and the dielectric constant of the material in between. The energy is contained within the dielectric. Running the cable in a metal conduit should have no effect at all, assuming the shield is complete.

It's not normally a good idea but not for this reason. Running coax through conduit, metal or otherwise does not change the impedance. The impedance is basically determined by the ratio of the OD of the inner conductor and the ID of the outer conductor.

There is no such thing as zero VSWR. There is at best 1:1 and I don't aim for that as I use antenna tuners in the shack to drive antennas on the other end with over a KW. I'd guess some of the cables easily have a VSWR as high as 6 or 8:1 . I can and have run 4 ham stations at the same time on 1.8 through 50 MHz with no interaction, nor do I hear the computers or bother them.

All cables on the tower have the shields grounded at the top and bottom of the tower. They also come through a grounded bulkhead at the entrance to the basement. It's good quality coax, properly grounded with an elaborate system ground. (32 or 33 eight foot ground rods CadWelded (TM) to over 600 feet of bare #2) So far I've never had an instance of cross talk, or one system bothering another. What shows up on one cable from another comes in from the antennas. I'm also running TV antenna mounted preamps in close proximity to the triband beam (14, 21, and 28 MHz) as well as both 50 and 144 MHz. I run the legal limit (1500 watts output) on 1.8 through 30 MHz and will soon be doing so on the 50 MHz band. On the 144 MHz band I'm limited to 380 watts into the top beams due to RF exposure levels. However when the duty cycle is taken into account I could run the legal limit on SSB if I had the amp. I also run FM and Digital at the same time on the 144 MHz band with a third station on SSB (which is set up in my shop at present) Apologies to those who have seen these links before.

satellite dish does not show in the photo but it does show how close the UHF TV antennas are to the tribander above and the 144/440 vertical below them. The top antennas in the array are for 144 and

440. gives a better view of the ham antenna system at the top. It does not show the wire HF antennas (half wave slopers on 75) or the TV antennas.

But it works without a problem.

I have TV OTA, TV satellite, FM broadcast, Ham stations (plural) for HF, VHF and UHF all running together. It may be wrong, but In over 45 years of doing the same thing at different locations I've never had a problem. The satellite and OTA coax is then bundled with the Cable TV and broadband coax once it's in the house. When I say bundled they are taped together to form a nice neat, round bundle.

My grounding bulkhead shown in the bottom photo is no longer in the house, but all cables come through a grounding bulkhead prior to coming through the wall.

The first photo shows the cables prior to being "neatened" up a bit. The second photo shows the mass of cables pretty much as they still exist.

It may not be good practice but the practice has worked just fine for me for over 45 years at 4 different locations.

On top of it all the tower has been taking an average of 3 visually verified lightning strikes a year since it was installed. It took 5 this past summer. So far no damage, but the connectors on top are beginning to look pretty ratty with all the plating burned off.

Roger Halstead (K8RI & ARRL life member) (N833R, S# CD-2 Worlds oldest Debonair)

Since the formula for impedance of a coax does not have any values for whether it is in conduit or not, I would say your claim is probably wrong. At the very least, some more supporting evidince is in order.

Please provide references.

As for the transmit and receive in the same bundle, you are confusing RF on the outside of the coax with the RF inside the coax. SWR mismatch, does not specifically cause RF on the outside of the coax. Operating balanced loads without baluns of some sort would, but that is different than a simple SWR mismatch.

Even if there were RF on the outside of the coax, if the receive feedline is properly set up, it won't be sensitive to it.

Alan

(And, yes, when I was 19 I studied for an afternoon then spent a couple hours the next day getting the First Phone license. The amateur licenses were much harder.)